Document:

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                                                                   Exhibit 10-Nn

                                FIFTH AMENDMENT
                                       TO
                     AMENDED AND RESTATED CREDIT AGREEMENT

     THIS FIFTH AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT (this
"Amendment"), dated as of March 6, 2002, is entered into by and among HERCULES
INCORPORATED, a Delaware corporation (the "Company"), BETZDEARBORN CANADA, INC.,
an Ontario corporation (the "Canadian Borrower"), certain subsidiaries of the
Company identified on the signature pages hereto (the "Guarantors"), the several
banks and other financial institutions identified on the signature pages hereto,
BANK OF AMERICA, N.A., as administrative agent (the "Administrative Agent") and
BANK OF AMERICA, N.A., acting through its Canadian branch, as Canadian
administrative agent (the "Canadian Administrative Agent"). Except as otherwise
defined in this Amendment, terms defined in the Credit Agreement referred to
below (as amended by this Amendment) are used herein as defined therein.

                                    RECITALS
                                    --------

     A.   The Company, the Canadian Borrower, the Subsidiary Guarantors party
thereto, the Lenders party thereto, the Administrative Agent and the Canadian
Administrative Agent entered into that certain Amended and Restated Credit
Agreement dated as of April 19, 1999 (as amended by that First Amendment to
Amended and Restated Credit Agreement dated as of March 31, 2000, that Second
Amendment to Amended and Restated Credit Agreement dated as of July 26, 2000,
that Third Amendment to Amended and Restated Credit Agreement dated as of
November 14, 2000, and that Fourth Amendment to Amended and Restated Credit
Agreement dated as of July 17, 2001, and as may be further amended, restated,
modified or supplemented from time to time, the "Credit Agreement").

     B.   The Company has requested certain modifications to the Credit
Agreement.

     C.   Such modifications require the consent of the Required Lenders.

     D.   The Required Lenders have consented to the requested modifications on
the terms and conditions set forth herein.

                                   AGREEMENT
                                   ---------

     NOW, THEREFORE, IN CONSIDERATION of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

<PAGE>
I.   ARTICLE I - IMMEDIATELY EFFECTIVE AMENDMENTS TO CREDIT AGREEMENT

     Subject to the satisfaction of the conditions precedent set forth in
Section 5 in Article III hereof, from and after the Fifth Amendment Effective
Date (as defined below), the Credit Agreement is hereby amended in the
following respects:

     1.   Section 2.6(b)(ii) of the Credit Agreement is hereby deleted in its
          entirety and the following substituted therefor:

          (ii) Asset Dispositions.

               (A)  If and whenever any Credit Party or any Subsidiary of a
          Credit Party receives any Net Cash Proceeds from any Asset Disposition
          relating to the assets of the Resins Division or equity interests in
          any Subsidiary holding assets of the Resins Division, the Borrowers
          shall, within five Business Days thereafter, apply 100% of such Net
          Cash Proceeds as set forth in clause (v) below.

               (B)  If and whenever any Credit Party or any Subsidiary of a
          Credit Party receives any Net Cash Proceeds from any Asset
          Disposition relating to the assets of FiberVisions or equity interests
          in FiberVisions, the Borrower shall within 5 Business Days
          thereafter, apply 100% of the Net Cash Proceeds as set forth in
          clause (v) below.

               (C)  If and whenever any Credit Party or any Subsidiary of a
          Credit Party receives any Net Cash Proceeds from the BetzDearborn
          Sale, the Borrower shall immediately apply 100% of the Net Cash
          Proceeds as set forth in clause (v) below (to the extent required in
          such clause).

               (D)  The Net Cash Proceeds from any Asset Disposition (other
          than as described in clauses (ii)(A), (ii)(B) or (ii)(C) hereof) or
          Involuntary Disposition received at any time by any Credit Party or
          any Subsidiary of a Credit Party may, within 180 days from the date
          of receipt, be applied (or caused to be applied) by the Company and
          its Consolidated Subsidiaries to make Eligible Reinvestments. If and
          whenever any such Net Cash Proceeds in excess of $15,000,000 (in the
          aggregate from the Third Amendment Effective Date) are not reinvested
          in Eligible Reinvestments prior to the expiration of such 180-day
          period, the Borrowers shall, on the first Business Day thereafter,
          apply such excess unreinvested amount as set forth in clause (v)
          below.

     2.   Subsections 2.6(b)(v)(I) and 2.6(b)(v)(J) of the Credit Agreement are
          hereby deleted in their entirety and the following substituted
          therefor:

               (I)  with respect to all amounts prepaid pursuant to subsections
          2.6(b)(ii)(B), 2.6(b)(ii)(D), 2.6(b)(iii)(B), and 2.6(b)(iv), to
          reduce, pro rata as set

                                       2
<PAGE>
     forth in clause (f) below, (I) ratably, each Tranche of outstanding Term
     Loans (credited pro rata across the amortization payment maturities in such
     Tranche), until the Term Loans are paid in full, then Revolving Credit
     Loans (credited pro rata among U.S. Revolving Loans, Multicurrency
     Revolving Loans and Canadian Revolving Loans, with corresponding permanent
     reductions in the respective Revolving Committed Amounts) and when all
     Revolving Credit Loans have been repaid to a cash collateral account in
     respect of BA Revolving Obligations and LOC Obligations on a pro rata
     basis, and then to Swingline Loans and (II) the Prudential Obligations,

          (J)  with respect to all amounts prepaid pursuant to subsection
     2.6(b)(ii)(C), to reduce, pro rata as set forth in clause (f) below, (I)
     ratably, each Tranche of outstanding Term Loans (credited pro rata across
     the amortization payment maturities in such Tranche), until the Term Loans
     are paid in full, then Revolving Credit Loans (credited pro rata among U.S.
     Revolving Loans, Multicurrency Revolving Loans and Canadian Revolving
     Loans, with permanent reductions in the respective Revolving Committed
     Amounts such that (i) the aggregate of the Revolving Committed Amounts
     after the BetzDearborn Sale shall equal (x) $200,000,000 (of which
     $170,000,000 shall be allocated to the Multicurrency Revolving Committed
     Amount, $30,000,000 shall be allocated to the U.S. Revolving Committed
     Amount and $0 shall be allocated to the Canadian Revolving Committed
     Amount) plus (y) an amount equal to the LOC Obligations outstanding on the
     BetzDearborn Sale Effective Date (85% of which shall be allocated to the
     Multicurrency Revolving Committed Amount and 15% of which shall be
     allocated to the U.S. Revolving Committed Amount and (ii) the LOC Committed
     Amount shall equal the amount of the LOC Obligations outstanding on the
     BetzDearborn Sale Effective Date), and when all Revolving Credit Loans have
     been repaid, to a cash collateral account in respect of BA Revolving
     Obligations and LOC Obligations on a pro rata basis, and then to Swingline
     Loans and (II) the Prudential Obligations, and

          (K)  with respect to all amounts prepaid pursuant to subsection
     2.6(b)(iii)(A), first to Revolving Credit Loans (credited pro rata among
     U.S. Revolving Loans, Multicurrency Revolving Loans and Canadian Revolving
     Loans) and to permanently reduce the Revolving Committed Amounts (on a pro
     rata basis), until all Revolving Committed Amounts are reduced to zero, and
     then ratably to each Tranche of outstanding Term Loans (credited pro rata
     across amortization payment maturities in such Tranche).

3.   Section 2.6(f) of the Credit Agreement is hereby amended by deleting the
     phrase "subsections 2.6(b)(v)(H) and (I) above" and replacing it with the
     phrase "subsections 2.6(b)(v)(H), (I) and (J) above".

4.   A new clause (1) is hereby added to the end of Section 2.16 of the Credit
     Agreement to read as follows:

                                       3

<PAGE>
          (l)  Reduction of the LOC Committed Amount. From and after the
     BetzDearborn Sale Effective Date, the LOC Committed Amount shall be
     permanently reduced by the amount of any Letters of Credit that are
     outstanding on the BetzDearborn Sale Effective Date which are not
     subsequently renewed or extended in accordance with the provisions of this
     Section 2.16 (with a corresponding reduction in the Revolving Committed
     Amount on a pro rata basis among the Multicurrency Revolving Committed
     Amount and the U.S. Revolving Committed Amount).

5.   Section 5.2(d)(i) of the Credit Agreement is hereby deleted in its entirety
     and the following substituted therefor:

          (i)  Leverage Ratio. It will not permit, as of the last day of any
     fiscal quarter, the Leverage Ratio to exceed the ratio set forth below for
     the applicable period:

<Table>
<Caption>
                      Period                             Maximum Leverage Ratio
                      ------                             ----------------------
<S>                                                      <C>
     Closing Date through March 31, 1999                       5.0 to 1.0
     April 1, 1999 through September 30, 1999                  4.5 to 1.0
     October 1, 1999 through March 31, 2000                    3.5 to 1.0
     April 1, 2000 through June 30, 2000                       3.75 to 1.0
     July 1, 2000 through September 30, 2000                   3.5 to 1.0
     October 1, 2000 through June 30, 2001                     4.75 to 1.0
     July 1, 2001 through September 30, 2001                   5.25 to 1.0
     October 1, 2001 through December 31, 2001                 5.00 to 1.0
     January 1, 2002 through March 31, 2002                    4.75 to 1.0
     April 1, 2002 through June 30, 2002                       4.50 to 1.0
     July 1, 2002 and thereafter                               4.25 to 1.0
</Table>

     Notwithstanding the foregoing, during the BetzDearborn Sale Period (and,
     with respect to any relevant period ending prior to the BetzDearborn Sale
     Effective Date only, from and after the BetzDearborn Sale Effective Date)
     the applicable maximum Leverage Ratio for the fiscal quarter periods ending
     as of March 31, 2002 and June 30, 2002 shall be 5.50 to 1.0. Upon the
     expiration of the BetzDearborn Sale Period without the BetzDearborn Sale
     Effective Date having occurred, if the Credit Parties were not in
     compliance with the covenant levels set forth in the table above for the
     applicable period, then an Event of Default shall exist.

6.   Section 5.2(d)(iii) of the Credit Agreement is hereby deleted in its
     entirety and the following substituted therefor:

          (iii)     Interest Coverage Ratio. It will not permit, as of the last
     day of any fiscal quarter, the Interest Coverage Ratio to be less than the
     ratio set forth below for the applicable period:

                                       4
<PAGE>
<Table>
<Caption>
                                             Minimum Interest
          Period                             Coverage Ratio
          ------                             ----------------
<S>                                          <C>
Closing Date through September 30, 1999       2.5 to 1.0
October 1, 1999 through September 30, 2000    3.0 to 1.0
October 1, 2000 through June 30, 2001        1.75 to 1.0
July 1, 2001 through September 30, 2001      1.65 to 1.0
October 1, 2001 through December 31, 2001    1.75 to 1.0
January 1, 2002 and thereafter               2.00 to 1.0
</Table>

     Notwithstanding the foregoing, during the BetzDearborn Sale Period (and,
     with respect to any relevant period ending prior to or after the
     BetzDearborn Sale Effective Date, from and after the BetzDearborn Sale
     Effective Date) the applicable minimum Interest Coverage Ratio for the
     fiscal quarter periods ending as of March 31, 2002 and June 30, 2002 shall
     be 1.75 to 1.0. Upon the expiration of the BetzDearborn Sale Period without
     the BetzDearborn Sale Effective Date having occurred, if the Credit Parties
     were not in compliance with the covenant levels set forth in the table
     above for the applicable period, then an Event of Default shall exist.

7.   Section 5.2(b)(ii)(C) of the Credit Agreement is hereby deleted in its
     entirety and the following substituted therefor:

          (C)  if such transaction is a sale, lease or other disposition of
     assets, (I) such transaction is not an Asset Disposition, (II) such
     transaction is an Asset Disposition of the Resins Division or FiberVision,
     (III) such transaction is the BetzDearborn Sale or (IV) the aggregate value
     of the assets sold, leased or disposed of in such transaction, when added
     to the aggregate value of all assets sold, leased or disposed of in all
     transactions permitted by this clause (IV) at any time after the Third
     Amendment Effective Date, does not exceed $50,000,000.

8.   Section 7 of the Credit Agreement is hereby amended by adding the following
     definitions in the appropriate alphabetical order:

          "BetzDearborn Purchase Agreement": that certain Stock and Asset
     Purchase Agreement dated as of February 12, 2002 entered into by and among
     the Company, General Electric Company and Falcon Acquisition Corp. as such
     agreement may be amended, restated, modified or supplemented from time to
     time.

          "BetzDearborn Sale": shall mean the sale of the water business of the
     Company (i) conducted through the BetzDearborn Division of the Company and
     (ii) through the Pulp and Paper Division of the Company and its Affiliates,
     Inc. pursuant to the BetzDearborn Purchase Agreement for an aggregate
     purchase price

                                       5
<PAGE>
     of approximately $1,800,000,000 in cash, subject to adjustment as provided
     in such agreement, but resulting in minimum Net Cash Proceeds of
     $1,600,000,000.

          "BetzDearborn Sale Effective Date": the date upon which the
     BetzDearborn Sale is consummated and the Borrower prepays the Loans in
     accordance with requirements of Section 2.6(b) hereof.

          "BetzDearborn Sale Period": shall mean the period from the Fifth
     Amendment Effective Date to the earliest of (i) the date upon which the
     BetzDearborn Purchase Agreement is terminated, (ii) BetzDearborn Sale
     Effective Date and (iii) July 15, 2002.

          "Fifth Amendment": that certain Fifth Amendment to Amended and
     Restated Credit Agreement dated as of March 6, 2002 by and among the
     Company, the Guarantors, the Lenders party thereto, the Administrative
     Agent and the Canadian Administrative Agent.

          "Fifth Amendment Effective Date": the date on which each of the
     conditions precedent to the effectiveness of the Fifth Amendment is
     satisfied by the Credit Parties or waived by the Administrative Agent
     and/or the Required Lenders, as applicable.

9.   The definition of Consolidated EBITDA in Section 7 of the Credit Agreement
     is hereby deleted in its entirety and the following substituted therefor,
     with such amendment to be deemed effective as of December 31, 2001:

          "Consolidated EBITDA": for any fiscal period, (i) Consolidated Net
     Income for such period, plus (ii) Consolidated Interest Expense for such
     period, plus (iii) to the extent deducted in computing such Consolidated
     Net Income, the sum of (a) taxes, (b) depreciation, (c) amortization, (d)
     any non-cash charges, (e) for the fiscal quarter ended June 30, 2001
     through the fiscal quarter ended June 30, 2002 only, any non-recurring cash
     charges associated with the restructuring of the Company and its
     Subsidiaries initiated on or after April 1, 2001 in an aggregate amount not
     to exceed $50 million, (f) for the fiscal quarter ended December 31, 2001
     through the fiscal quarter ended December 31, 2002 only, any non-recurring
     cash charges associated with the reduction-in-force by the Company and its
     Subsidiaries in an aggregate amount not to exceed $125 million and (g) any
     extraordinary, unusual or non-recurring cash losses or cash charges
     incurred in connection with (x) the Acquisition in an amount not to exceed
     $170 million after taxes in the aggregate for all such add-backs pursuant
     to this subclause (x), (y) the settlement prior to the Closing Date of
     certain litigation in an amount not to exceed $63 million after taxes in
     the aggregate for all such add-backs pursuant to this subclause (y), minus
     (iv) any extraordinary gains and noncash gains.

                                       6

<PAGE>
     10.  Section 9.6(c) of the Credit Agreement is hereby amended by deleting
          the first proviso of the first sentence thereof in its entirety and
          the following substituted therefor:

          provided, however, that the amount of the Commitment (if any) of the
          assigning Lender being assigned pursuant to each such assignment
          (determined as of the date of the Assignment and Acceptance with
          respect to such assignment) shall in no event be less than (unless
          agreed upon by the Administrative Agent and the Borrower) the lesser
          of (i) $1,000,000 and (ii) with respect to each assigning Lender, the
          amount of such Lender's Commitment;

     11.  A new Section 9.21 is hereby added to the end of Section 9 of the
          Credit Agreement to read as follows:

          9.21. Reorganization in Connection with BetzDearborn Sale.

                In connection with the BetzDearborn Sale and notwithstanding
          any provision of the Credit Documents to the contrary, the Credit
          Parties and their subsidiaries may take such intercompany actions as
          are reasonably necessary to consummate the Reorganization defined in
          and referred to in the BetzDearborn Purchase Agreement (including
          without limitation intercompany mergers, liquidations and asset
          transfers related to separating the Water Business (as defined in the
          BetzDearborn Purchase Agreement) from the Company's other
          businesses); provided, however, that (a) the Credit Parties shall
          make commercially reasonable efforts to maintain the Collateral
          Agent's collateral position as of the Fifth Amendment Effective Date
          (including without limitation by promptly causing any newly formed
          subsidiaries to execute Guarantor Joinder Agreements and otherwise
          comply with the terms of subsection 5.1(j) and (b) upon the
          expiration of the BetzDearborn Sale Period without the BetzDearborn
          Sale Effective Date having occurred, the Credit Parties shall, within
          30 days of such expiration (or such longer period of time as the
          Collateral Agent may reasonably agree to if the Credit Parties are
          diligently pursuing such actions in good faith) take such actions as
          are reasonably necessary to put the Collateral Agent in a collateral
          position that is as good as such collateral position as of the Fifth
          Amendment Effective Date.

II.  ARTICLE II - AMENDMENTS TO THE CREDIT AGREEMENT EFFECTIVE UPON THE
     BETZDEARBORN SALE EFFECTIVE DATE

     Subject to the satisfaction of the conditions precedent set forth in
Section 5 in Article III hereof, from and after the BetzDearborn Sale Effective
Date, the Required Lenders hereby agree to amend the Credit Agreement in the
following respects:

     1.   Section 5.1(j) of the Credit Agreement is hereby deleted in its
          entirety and the following substituted therefor:

                                       7
<PAGE>
          (j) Additional Credit Parties. At the time any Person becomes a
     Domestic Subsidiary (other than a Receivables Financing SPC or a Preferred
     Stock SPC or as otherwise agreed to by the Administrative Agent) or becomes
     a guarantor with respect to any other Indebtedness of the Company, the
     Company shall so notify the Administrative Agent and promptly thereafter
     (but in any event within 30 days after the date thereof) shall (a) cause
     such Person to execute a Guarantor Joinder Agreement in substantially the
     same form as Exhibit E, (b) cause such Person to execute counterparts of,
     or a joinder in, the Security Agreement, and (c) deliver, or cause such
     Person to deliver, such other documentation as the Collateral Agent may
     reasonably request in connection with the foregoing, including, without
     limitation, certified resolutions and other organizational and authorizing
     documents of such Person, favorable opinions of counsel to such Person
     (which shall cover, among other things, the legality, validity, binding
     effect and enforceability of the documentation referred to above) and
     appropriate UCC-1 financing statements, all in form, content and scope
     reasonably satisfactory to the Collateral Agent.

2.   Section 5.2(b)(ii)(B) of the Credit Agreement is hereby deleted in its
     entirety and the following substituted therefor:

          (B)  if such transaction is a purchase, the cash purchase price of
     such purchase along with the cash purchase prices of all such other
     purchases consummated pursuant to this subsection 5.2(b)(ii)(B) in each
     fiscal year does not exceed $150,000,000; and

3.   Section 5.2(b)(ii)(C) of the Credit Agreement is hereby deleted in its
     entirety and the following substituted therefor:

          (C)  if such transaction is a sale, lease or other disposition of
     assets, (I) such transaction is not an Asset Disposition, (II) such
     transaction is an Asset Disposition of the Resins Division or FiberVision,
     (III) such transaction is the BetzDearborn Sale or (IV) the aggregate value
     of the assets sold, leased or disposed of in such transaction, when added
     to the aggregate value of all assets sold, leased or disposed of in all
     transactions permitted by this clause (IV) at any time after the Fifth
     Amendment Effective Date, does not exceed $50,000,000.

4.   A new Section 9.22 is hereby added to the end of Section 9 of the Credit
     Agreement to read as follows:

     9.22 Release of Pledged Stock.

          Upon the BetzDearborn Sale Effective Date, the pledges and grants of
     security interests in the Pledged Collateral (as defined in the Pledge
     Agreement) shall be deemed released and the covenants and other agreements
     contained in the

                                       8

<PAGE>
          Pledge Agreement shall otherwise cease and be of no further force and
          effect as to the Credit Parties. Promptly following the BetzDearborn
          Sale Effective Date, the Collateral Agent shall, at the Credit Parties
          expense, deliver to the Credit Parties such documentation as is
          reasonably necessary to evidence the Collateral Agent's release of its
          security interest in the Pledged Collateral (as defined in the Pledge
          Agreement) including without limitation the return of the stock
          certificates and stock powers delivered to the Collateral Agent
          thereunder.

III. MISCELLANEOUS

     1. Representations and Warranties. Each of the Credit Parties represents
and warrants to the Lenders, the Administrative Agent and the Canadian
Administrative Agent as follows:

          (i)    It has taken all necessary action to authorize the execution,
     delivery and performance of this Amendment.

          (ii)   This Amendment has been duly executed and delivered by such
     Credit Party and constitutes such Credit Party's legal, valid and binding
     obligation, enforceable in accordance with its terms, except as such
     enforceability may be limited (x) by general principles of equity and
     conflicts of laws or (y) by bankruptcy, reorganization, insolvency,
     moratorium or other laws of general application relating to or affecting
     the enforcement of creditors' rights.

          (iii)  No consent, approval, authorization or order of, or filing,
     registration or qualification with, any court or governmental authority or
     third party is required in connection with the execution, delivery or
     performance by such Credit Party of this Amendment.

          (iv)   The execution and delivery of this Amendment does not diminish
     or reduce its obligations under the Credit Documents (including, without
     limitation, in the case of each Guarantor, such Guarantor's guaranty
     pursuant to Section 3A of the Credit Agreement) in any manner, except as
     specifically set forth herein.

          (v)    Such Credit Party has no claims, counterclaims, offsets, or
     defenses to the Credit Documents and the performance of its obligations
     thereunder, or if such Credit Party has any such claims, counterclaims,
     offsets, or defenses to the Credit Documents or any transaction related to
     the Credit Documents, the same are hereby waived, relinquished and
     released in consideration of the Required Lenders' execution and delivery
     of this Amendment.

          (vi)   The representations and warranties of the Credit Parties set
     forth in Section 1 of the Credit Agreement are true and correct as of the
     date hereof (except those that expressly relate to an earlier date) and
     all of the provisions of the Credit Documents, except as amended hereby,
     are in full force and effect.

                                       9

<PAGE>
          (vii)     Subsequent to the execution and delivery of this Amendment
     and after giving effect hereto, no unwaived event has occurred and is
     continuing which constitutes a Default or an Event of Default.

     2.   Liens. Subject to the release of the Pledged Collateral upon the
BetzDearborn Sale Effective Date as set forth in Section 3 of Article III
hereof, each Credit Party affirms the liens and security interests created and
granted by it in the Credit Documents (including, but not limited to, the
Pledge Agreement, the Security Agreement and the Mortgages) and agrees that
this Amendment shall in no manner adversely affect or impair such liens and
security interests.

     3.   Effect of Amendment. Except as expressly modified and amended in this
Amendment, all of the terms, provisions and conditions of the Credit Documents
shall remain unchanged and in full force and effect. The Credit Documents and
any and all other documents heretofore, now or hereafter executed and delivered
pursuant to the terms of the Credit Agreement are hereby amended so that any
reference to the Credit Agreement shall mean a reference to the Credit
Agreement as amended hereby.

     4.   Expenses. The Company agrees to pay all reasonable costs and expenses
incurred in connection with the preparation, execution and delivery of this
Amendment, including the reasonable fees and expenses of the Administrative
Agent's legal counsel.

     5.   Conditions Precedent. Article I of this Amendment shall become
effective on the date hereof (the "Fifth Amendment Effective Date") once each
of the following conditions precedent has been satisfied:

          (a)  the Administrative Agent shall have received counterparts of this
     Amendment, duly executed and delivered by each of the Credit Parties, the
     Required Lenders and by the Administrative Agent and the Canadian
     Administrative Agent;

          (b)  the Administrative Agent shall have received from a Responsible
     Officer of the Company a certificate to the effect that as of the date
     hereof and as of the Fifth Amendment Effective Date all representations and
     warranties made by the Company and each other Credit Party in this
     Amendment and each other Credit Document are true and correct in all
     material respects; and

          (c)  no Default or Event of Default shall have occurred and be
     continuing.

     Article II of this Amendment shall become effective only after the
occurrence of both the Fifth Amendment Effective Date and the BetzDearborn Sale
Effective Date.

     6.   Counterparts. This Amendment may be executed in any number of
counterparts and by the parties hereto in separate counterparts, each of which
when so executed and delivered shall be deemed to be an original and all of
which taken together shall constitute one and the same instrument.

                                       10
<PAGE>
     7.   Governing Law. This Amendment shall be governed by and construed in
accordance with the laws of the State of North Carolina.

     8.   ENTIRETY. THIS AMENDMENT, THE CREDIT AGREEMENT AND THE OTHER CREDIT
DOCUMENTS EMBODY THE ENTIRE AGREEMENT BETWEEN THE PARTIES AND SUPERSEDE ALL
PRIOR AGREEMENTS AND UNDERSTANDINGS, IF ANY, RELATING TO THE SUBJECT MATTER
HEREOF. THESE CREDIT DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE
PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR
SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

                                       11
<PAGE>
     IN WITNESS WHEREOF, the parties hereto have caused this Amendment, to be
duly executed and delivered by their proper and duly authorized officers as of
the day and year first above written.

THE COMPANY:                  HERCULES INCORPORATED,
                              a Delaware corporation

                              By: /s/ Stuart C. Shears
                                  -----------------------------------
                                  Name: Stuart C. Shears
                                  Title: Vice President and Treasurer

CANADIAN BORROWER:            BETZDEARBORN CANADA, INC.,
                              an Ontario corporation

                              By: /s/ Stuart C. Shears
                                  -----------------------------------
                                  Name: Stuart C. Shears
                                  Title: Authorized Representative<PAGE>
                                                                     Exhibit 4.1

                  THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
                  ACT OF 1933 OR THE LAWS OF ANY STATE. THEY MAY NOT BE SOLD OR
                  OTHERWISE TRANS- FERRED UNLESS THEY ARE REGISTERED UNDER SUCH
                  ACT AND APPLICABLE STATE SECURITIES LAWS OR AN EXEMPTION FROM
                  REGISTRATION IS AVAILABLE.

                                                             670,500 Warrants

                           PRINCETON VIDEO IMAGE, INC.

                               WARRANT CERTIFICATE

                  This warrant certificate ("Warrant Certificate") certifies
that for good and valuable consideration, the sufficiency of which is hereby
acknowledged, SciDel Technologies, Ltd. or registered permitted assigns (the
"Holder") is the owner of the number of warrants ("Warrants") specified above,
each of which entitles the Holder thereof to purchase, at any time after the
Warants vest and become exercisable and on or before the Expiration Date (as
hereinafter defined), one fully paid and non-assessable share of Common Stock,
$.001 par value ("Common Stock"), of Princeton Video Image, Inc., a Delaware
corporation (the "Company"), at a purchase price of $9.00 per share of Common
Stock in lawful money of the United States of America in cash or by certified or
cashier's check or a combination of cash and certified or cashier's check
(subject to adjustment as hereinafter provided).

                  1. Warrant; Purchase Price

                  Each Warrant shall entitle the Holder initially to purchase
one share of Common Stock of the Company and the purchase price payable upon
exercise of the Warrants (the "Purchase Price") shall initially be $9.00 per
share of Common Stock. The Purchase Price and number of shares of Common Stock
issuable upon exercise of each Warrant are subject to adjustment as provided in
Article 6. The shares of Common Stock issuable upon exercise of the Warrants
(and/or other shares of common stock so issuable by reason of any adjustments
pursuant to Article 6) are sometimes referred to herein as the "Warrant Shares."

                  2. Exercise; Expiration Date

                  2.1 Two hundred twenty-three thousand five hundred (223,500)
of the Warrants shall vest and become exercisable on each of the first, second
and third anniversaries of the date hereof and upon such vesting shall be
exercisable, at the option of the Holder, in whole or in part at any time and
from time to time on or before the Expiration Date, upon

                                       1
<PAGE>

surrender of this Warrant Certificate to the Company together with a duly
completed Notice of Exercise, in the form attached hereto as Exhibit A, and
payment of an amount equal to the Purchase Price times the number of Warrants to
be exercised. In the case of exercise of less than all the Warrants represented
by this Warrant Certificate, the Company shall cancel the Warrant Certificate
upon the surrender thereof and shall execute and deliver a new Warrant
Certificate for the balance of such Warrants.

                  2.2 The term "Expiration Date" shall mean 5:00 p.m. New York
time on the fifth anniversary hereof.

                  3. Registration and Transfer on Company Books

                  3.1 The Company shall maintain books for the registration and
transfer of the Warrants and the registration and transfer of the Warrant
Shares.

                  3.2 Prior to due presentment for registration of transfer of
this Warrant Certificate, or the Warrant Shares, the Company may deem and treat
the registered Holder as the absolute owner thereof.

                  3.3 Neither this Warrant Certificate, nor the Warrants
represented hereby, may be sold, assigned or otherwise transferred voluntarily
by the Holder, other than to a party named on Schedule A hereto (a "Permitted
Transfer"), without the consent of the Company. The Company shall register upon
its books any Permitted Transfer of a Warrant Certificate, upon surrender of
same to the Company with a written instrument of transfer duly executed by the
registered Holder or by a duly authorized attorney. Upon any such registration
of Permitted Transfer, new Warrant Certificate(s) shall be issued to the
transferee(s) and the surrendered Warrant Certificate shall be canceled by the
Company. A Warrant Certificate may also be exchanged, at the option of the
Holder, for new Warrant Certificates of different denominations representing in
the aggregate the number of Warrants evidenced by the Warrant Certificate
surrendered.

                  3.4 No sale, transfer, assignment, hypothecation or other
disposition of the Warrant Shares shall be made unless any such transfer,
assignment or other disposition will comply with the rules and statutes
administered by the Securities and Exchange Commission (the "Commission") and
(i) a registration statement under the Securities Act of 1933, as amended (the
"Act"), including such shares is currently in effect, or (ii) in the opinion of
counsel satisfactory to the Company a current registration statement is not
required for such disposition of the shares.

                  4. Reservation of Shares

                  The Company covenants that it will at all times reserve and
keep available out of its authorized capital stock, solely for the purpose of
issue upon exercise of the Warrants, such number of shares of capital stock as
shall then be issuable upon the exercise of all outstanding Warrants. The
Company covenants that all shares of capital stock which shall be issuable upon
exercise of the Warrants shall be duly and validly issued and fully paid and
non-assessable and

                                       2
<PAGE>

free from all taxes, liens and charges with respect to the issue thereof, and
that upon issuance such shares shall be listed on each national securities
exchange or automated over-the-counter trading system, if any, on which the
other shares of such outstanding capital stock of the Company are then listed.

                  5. Loss or Mutilation

                  Upon receipt by the Company of reasonable evidence of the
ownership of and the loss, theft, destruction or mutilation of any Warrant
Certificate and, in the case of loss, theft or destruction, of indemnity
reasonably satisfactory to the Company, or, in the case of mutilation, upon
surrender and cancellation of the mutilated Warrant Certificate, the Company
shall execute and deliver in lieu thereof a new Warrant Certificate representing
an equal number of Warrants.

                  6. Adjustment of Purchase Price and Number of Shares
Deliverable

                  6.1 The number of Warrant Shares purchasable upon the exercise
of each Warrant and the Purchase Price with respect to the Warrant Shares shall
be subject to adjustment as follows:

                  (a) In case the Company shall (i) declare a dividend or make a
distribution on its Common Stock payable in shares of its capital stock, (ii)
subdivide its outstanding shares of Common Stock through stock split or
otherwise, (iii) combine its outstanding shares of Common Stock into a smaller
number of shares of Common Stock, or (iv) issue by reclassification of its
Common Stock (including any reclassification in connection with a consolidation
or merger in which the Company is the continuing corporation) other securities
of the Company, the number and/or nature of Warrant Shares purchasable upon
exercise of each Warrant immediately prior thereto shall be adjusted so that the
Holder shall be entitled to receive the kind and number of Warrant Shares or
other securities of the Company which he would have owned or have been entitled
to receive after the happening of any of the events described above, had such
Warrant been exercised immediately prior to the happening of such event or any
record date with respect thereto. Any adjustment made pursuant to this paragraph
(a) shall become effective retroactively as of the record date of such event.

                  (b) In the event of any capital reorganization or any
reclassification of the capital stock of the Company or in case of the
consolidation or merger of the Company with another corporation (other than a
consolidation or merger in which the outstanding shares of the Company's Common
Stock are not converted into or exchanged for other rights or interests), or in
the case of any sale, transfer or other disposition to another corporation of
all or substantially all the properties and assets of the Company (any such
event, a "Triggering Event"), the Holder of each Warrant shall thereafter be
entitled to purchase (and it shall be a condition to the consummation of any
such reorganization, reclassification, consolidation, merger, sale, transfer or
other disposition that appropriate provisions shall be made so that such Holder
shall thereafter be entitled to purchase) the kind and amount of shares of stock
and other securities and property (including cash) which the Holder would have
been entitled to receive had such Warrants been

                                       3
<PAGE>

exercised immediately prior to the effective date of such reorganization,
reclassification, consolidation, merger, sale, transfer or other disposition;
and in any such case appropriate adjustments shall be made in the application of
the provisions of this Article 6 with respect to rights and interest thereafter
of the Holder of the Warrants to the end that the provisions of this Article 6
shall thereafter be applicable, as near as reasonably may be, in relation to any
shares or other property thereafter purchasable upon the exercise of the
Warrants. The provisions of this Section 6.1(b) shall similarly apply to
successive reorganizations, reclassifications, consolidations, mergers, sales,
transfers or other dispositions.

                  (c) Whenever the number of Warrant Shares purchasable upon the
exercise of each Warrant is adjusted, as provided in this Section 6.1, the
Purchase Price with respect to the Warrant Shares shall be adjusted by
multiplying such Purchase Price immediately prior to such adjustment by a
fraction, of which the numerator shall be the number of Warrant Shares
purchasable upon the exercise of each Warrant immediately prior to such
adjustment, and of which the denominator shall be the number of Warrant Shares
so purchasable immediately thereafter.

                  6.2 No adjustment in the number of Warrant Shares purchasable
under the Warrants, or in the Purchase Price with respect to the Warrant Shares,
shall be required unless such adjustment would require an increase or decrease
of at least 1% in the number of Warrant Shares issuable upon the exercise of
such Warrant, or in the Purchase Price thereof; provided, however, that any
adjustments which by reason of this Section 6.2 are not required to be made
shall be carried forward and taken into account in any subsequent adjustment.
All final results of adjustments to the number of Warrant Shares and the
Purchase Price thereof shall be rounded to the nearest one thousandth of a share
or the nearest cent, as the case may be. Anything in this Section 6 to the
contrary notwithstanding, the Company shall be entitled, but shall not be
required, to make such changes in the number of Warrant Shares purchasable upon
the exercise of each Warrant, or in the Purchase Price thereof, in addition to
those required by such Section, as it in its discretion shall determine to be
advisable in order that any dividend or distribution in shares of Common Stock,
subdivision, reclassification or combination of shares of Common Stock, issuance
of rights, warrants or options to purchase Common Stock, or distribution of
shares of stock other than Common Stock, evidences of indebtedness or assets
(other than distributions of cash out of retained earnings) or convertible or
exchangeable securities hereafter made by the Company to the holders of its
Common Stock shall not result in any tax to the holders of its Common Stock or
securities convertible into Common Stock.

                  6.3 Whenever the number of Warrant Shares purchasable upon the
exercise of each Warrant or the Purchase Price of such Warrant Shares is
adjusted, as herein provided, the Company shall mail to the Holder, at the
address of the Holder shown on the books of the Company, a notice of such
adjustment or adjustments, prepared and signed by the Chairman of the Board,
Chief Financial Officer or Secretary of the Company, which sets forth the number
of Warrant Shares purchasable upon the exercise of each Warrant and the Purchase
Price of such Warrant Shares after such adjustment, a brief statement of the
facts requiring such adjustment and the computation by which such adjustment was
made.

                                       4
<PAGE>

                  6.4 The Company shall give notice to the Holder by registered
mail, if at any time prior to the expiration or exercise in full of the
Warrants, any of the following events shall occur:

                  (a) The Company shall authorize the payment of any dividend
payable in any securities upon shares of Common Stock or authorize the making of
any distribution to the holders of shares of Common Stock;

                  (b) The Company shall authorize the issuance to all holders of
Common Stock of any additional shares of Common Stock or of rights, options or
warrants to subscribe for or purchase Common Stock or any of any other
subscription rights, options or warrants;

                  (c) A dissolution, liquidation or winding up of the Company
(other than in connection with a consolidation, merger, or sale or conveyance of
the property of the Company as an entirety or substantially as an entirety); or

                  (d) A capital reorganization or reclassification of the Common
Stock (other than a subdivision or combination of the outstanding Common Stock
and other than a change in the par value of the Common Stock) or any
consolidation or merger of the Company with or into another corporation (other
than a consolidation or merger in which the Company is the continuing
corporation and that does not result in any reclassification or change of Common
Stock outstanding) or any sale or conveyance to another corporation of the
property of the Company as an entirety or substantially an entirety.

Such giving of notice shall be initiated at least 10 business days prior to the
date fixed as a record date or effective date or the date of closing of the
Company's stock transfer books for the determination of the shareholders
entitled to such dividend, distribution, or subscription rights, or for the
determination of the shareholders entitled to vote on such proposed merger,
consolidation, sale, conveyance, dissolution, liquidation or winding up. Such
notice shall specify such record date or the date of the closing of the stock
transfer books, as the case may be. Failure to provide such notice shall not
affect the validity of any action taken in connection with such dividend,
distribution or subscription rights, or proposed merger, consolidation, sale,
conveyance, dissolution, liquidation or winding up.

                  7. Conversion Rights

                  7.1 In lieu of exercise of any portion of the Warrants as
provided in Section 2.1 hereof, the Warrants represented by this Warrant
Certificate (or any portion thereof) may, at the election of the Holder, be
converted into the nearest whole number of shares of Common Stock equal to: (1)
the product of (a) the number of shares of Common Stock then issuable upon the
exercise of the Warrants to be so converted and (b) the excess, if any, of (i)
the Market Price Per Share (as determined pursuant to Section 9.2) with respect
to the date of conversion over (ii) the Purchase Price in effect on the business
day next preceding the date of conversion, divided by (2) the Market Price Per
Share with respect to the date of conversion. For example, if the Market Price
per Share on the date of conversion is $4.00 and the Purchase Price is $2.00,
then the

                                       5
<PAGE>

Holder would be entitled to receive 15,000 shares of Common Stock upon
conversion of 30,000 Warrants.

                  7.2 The conversion rights provided under this Section 7 may be
exercised in whole or in part and at any time and from time to time while any
Warrants remain outstanding. In order to exercise the conversion privilege, the
Holder shall surrender to the Company, at its offices, this Warrant Certificate
accompanied by a duly completed Notice of Conversion in the form attached hereto
as Exhibit B. The Warrants (or so much thereof as shall have been surrendered
for conversion) shall be deemed to have been converted immediately prior to the
close of business on the day of surrender of such Warrant Certificate for
conversion in accordance with the foregoing provisions. As promptly as
practicable on or after the conversion date, the Company shall issue and shall
deliver to the Holder (i) a certificate or certificates representing the number
of shares of Common Stock to which the Holder shall be entitled as a result of
the conversion, and (ii) if the Warrant Certificate is being converted in part
only, a new certificate of like tenor and date for the balance of the
unconverted portion of the Warrant Certificate.

                  8. Voluntary Adjustment by the Company

                  The Company may, at its option, at any time during the term of
the Warrants, reduce the then current Purchase Price to any amount deemed
appropriate by the Board and/or extend the date of the expiration of the
Warrants.

                  9. Fractional Shares and Warrants; Determination of Market
Price Per Share

                  9.1 Anything contained herein to the contrary notwithstanding,
the Company shall not be required to issue any fraction of a share of Common
Stock in connection with the exercise of Warrants. Warrants may not be exercised
in such number as would result (except for the provisions of this paragraph) in
the issuance of a fraction of a share of Common Stock unless the Holder is
exercising all Warrants then owned by the Holder. In such event, the Company
shall, upon the exercise of all of such Warrants, issue to the Holder the
largest aggregate whole number of shares of Common Stock called for thereby upon
receipt of the Purchase Price for all of such Warrants and pay a sum in cash
equal to the remaining fraction of a share of Common Stock, multiplied by its
Market Price Per Share (as determined pursuant to Section 9.2 below) as of the
last business day preceding the date on which the Warrants are presented for
exercise.

                  9.2 As used herein, the "Market Price Per Share" with respect
to any class or series of Common Stock on any date shall mean the average
closing price per share of Company's Common Stock for the 20 trading days
immediately preceding such date. The closing price for each such day shall be
the last sale price regular way or, in case no such sale takes place on such
day, the average of the closing bid and asked prices regular way, in either case
on the principal securities exchange on which the shares of such Common Stock of
the Company are listed or admitted to trading or, if applicable, the last sale
price, or in case no sale takes place on such day, the average of the closing
bid and asked prices of such Common Stock on NASDAQ or any comparable system, or
if such Common Stock is not reported on NASDAQ, or a comparable

                                       6
<PAGE>

system, the average of the closing bid and asked prices as furnished by two
members of the National Association of Securities Dealers, Inc. selected from
time to time by the Company for that purpose. If such bid and asked prices are
not available, then "Market Price Per Share" shall be equal to the fair market
value of such Common Stock as determined in good faith by the Board.

                  10. Governing Law

                  This Warrant Certificate shall be governed by and construed in
accordance with the laws of the State of New Jersey.

                  IN WITNESS WHEREOF, the Company has caused this Warrant
Certificate to be duly executed by its officers thereunto duly authorized and
its corporate seal to be affixed hereon, as of this 26th day of March, 2002.

                                        PRINCETON VIDEO IMAGE, INC.

                                        By: /s/ L.L. Epstein
                                           --------------------------------
                                             Name: Lawrence Epstein
                                             Title:  Vice President and CFO

                                       7
<PAGE>
                                                                      SCHEDULE A

                              PERMITTED TRANSFEREES

---------------------------------------------------------------------------
 NO.  NAME                                    ADDRESS
---------------------------------------------------------------------------
 1.   Mooli Zahavi                            SciDel Technologies Ltd.
-------------------------------------------   P.O.B. 2335, Taya Center
 2.   Sigal Hanaya                            14 Haharoshet St.
-------------------------------------------   Ra'anana 44657, Israel
 3.   Aviva Harari                            Fax: 972-9-7437127
-------------------------------------------   Attn: Eitan Metuki
 4.   Kobi Bendel
-------------------------------------------
 5.   Ariel Matzkin
-------------------------------------------
 6.   Yuval Karoochi
-------------------------------------------
 7.   Oren Steinfeld
-------------------------------------------
 8.   Ofer Ash
-------------------------------------------
 9.   Dror Dagan
-------------------------------------------
 10.  Dmitry Dubnitzky
-------------------------------------------
 11.  Amit Eizenthal
-------------------------------------------
 12.  Haim Alon
-------------------------------------------
 13.  Yacov Weinberg
-------------------------------------------
 14.  Eyal Shamur
-------------------------------------------
 15.  Haim Ben Arosh
-------------------------------------------
 16.  Itay Zohar
-------------------------------------------
 17.  Yaniv Taigman
-------------------------------------------
 18.  Haim Kraitman
-------------------------------------------
 19.  Ofer Shamur
-------------------------------------------
 20.  Danny Barel
---------------------------------------------------------------------------

<PAGE>

---------------------------------------------------------------------------
 21.  Yoav Chelouche
-------------------------------------------
 22.  Eitan Metuki
---------------------------------------------------------------------------
 23.  Gemini Israel II
      Advent PGGM Gemini
      Gemini Israel II Parallel Fund
      Gemini Partner Investors
---------------------------------------------------------------------------
 24.  Scitex Corporation                      3 Azrieli Center, Triangle
                                                Building 45th Floor 132
                                              132 Menachem Begin Rd.
                                              Tel-Aviv 67023, Israel
                                              Fax: 972-3-6075756
                                              Attn: Yahel Shachar, CFO
---------------------------------------------------------------------------
 25.  Clal, Clal Electronics Industries
---------------------------------------------------------------------------
 26.  The Star Group
      Star Ventures
      SVE Venture Enterprise
---------------------------------------------------------------------------
 27.  Invision AG
---------------------------------------------------------------------------
 28.  Infinity Holdings Group
---------------------------------------------------------------------------
 29.  Eitan Ashash
---------------------------------------------------------------------------
 30.  Analog Devices
---------------------------------------------------------------------------
 31.  Bank Leumi
---------------------------------------------------------------------------
 32.  Bank Hapohalim
---------------------------------------------------------------------------
 33.  Darby & Darby
---------------------------------------------------------------------------
 34.  Fischer, Bachar, Chen & Co              Fischer, Behar, Chen & Co.
                                              3 Daniel Frisch Street
                                              Tel Aviv 64731, Israel
                                              Fax: 972-3-609-1117
                                              Attn: Elliot Dater, Adv.
---------------------------------------------------------------------------
 35.  Kesselman & Kesselman
---------------------------------------------------------------------------
 36.  Eitan, Pearl, Latzer & Cohen-Zedek
---------------------------------------------------------------------------
 37.  Morris, James, Hitchens & Williams
---------------------------------------------------------------------------

<PAGE>
                                                                     EXHIBIT A

                               NOTICE OF EXERCISE

                  The undersigned hereby irrevocably elects to exercise,
pursuant to Section 2 of the Warrant Certificate accompanying this Notice of
Exercise, _______ Warrants of the total number of Warrants owned by the
undersigned pursuant to the accompanying Warrant Certificate, and herewith makes
payment of the Purchase Price of such shares in full.

                                     Name of Holder
                                                       ------------------------

                                     Signature
                                                       ------------------------

                                     Address:
                                                       ------------------------

                                                       ------------------------

                                                       ------------------------

<PAGE>

                                                                    EXHIBIT B

                              NOTICE OF CONVERSION

The undersigned hereby irrevocably elects to convert, pursuant to Section 7 of
the Warrant Certificate accompanying this Notice of Conversion, _______ Warrants
of the total number of Warrants owned by the undersigned pursuant to the
accompanying Warrant Certificate into shares of the Common Stock of the Company
(the "Shares").

The number of Shares to be received by the undersigned shall be calculated in
accordance with the provisions of Section 7.1 of the accompanying Warrant
Certificate.

                                     Name of Holder
                                                       ------------------------

                                     Signature
                                                       ------------------------

                                     Address:
                                                       ------------------------

                                                       ------------------------

                                                       ------------------------

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