<PAGE>

                                                                    EXHIBIT 4.2

                                FIRST AMENDMENT


         FIRST AMENDMENT, dated as of February 17, 1998 (this "Amendment"), to
the Credit Agreement, dated as of May 16, 1997 (the "Credit Agreement"), among
W. R. Grace & Co.-Conn., a Connecticut corporation (the "Company"), W. R. Grace
& Co., a Delaware corporation and sole shareholder of the Company ("Grace
Delaware"), Grace Specialty Chemicals, Inc. a Delaware corporation ("New
Grace"), the several banks from time to time parties to the Credit Agreement
(the "Banks"), and The Chase Manhattan Bank, a New York banking corporation, as
administrative agent for the Banks thereunder (in such capacity, the
"Administrative Agent").


                             W I T N E S S E T H :

         WHEREAS, New Grace is wholly-owned by Grace Delaware and pursuant to
this Amendment will become a party to the Credit Agreement and a guarantor
under Section 12 of the Credit Agreement to the same extent Grace Delaware is a
guarantor, and will upon completion of the Packaging Transaction (as
hereinafter defined) replace Grace Delaware as guarantor;

         WHEREAS, in connection with the Packaging Transaction (as hereinafter
defined) (i) New Grace will become the sole shareholder of the Company, (ii)
the Company will transfer its packaging business to another subsidiary of Grace
Delaware and (iii) Grace Delaware will spin off New Grace (together with the
Company) to Grace Delaware's shareholders;

         WHEREAS, the Company has requested the Banks to, among other things,
consent to the Packaging Transaction on the terms and subject to the conditions
set forth herein;

         NOW THEREFORE, in consideration of the premises herein contained and
for other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties hereto hereby agree as follows:


                                   ARTICLE I.
                                  DEFINITIONS

         Unless otherwise defined herein, terms defined in the Credit Agreement
and used herein shall have the meanings given to them in the Credit Agreement.

<PAGE>

                                  ARTICLE II.
                          CREDIT AGREEMENT AMENDMENTS


         2.1 Definitions. (a) Subsection 1.1 of the Credit Agreement is hereby
amended by deleting the definition of "Loan Parties" in its entirety and by
adding the following new definitions to such subsection in correct alphabetical
order:

         `Cryovac': Cryovac, Inc., a Delaware corporation and subsidiary of the
    Company, together with its subsidiaries.

         `Grace Delaware': W.R. Grace & Co., a Delaware corporation and sole
    shareholder of the Company.

         `Loan Parties': the collective reference to the Company, the other
    Borrowers, Grace Delaware and New Grace.

         `New Grace': Grace Specialty Chemicals, Inc., a Delaware corporation.

         `Packaging Transaction': the transaction in which all of the following
    steps occur: (a) the Company will transfer its packaging business to
    Cryovac, (b) Grace Delaware and Cryovac will enter into new bank borrowings
    of approximately $1,200,000 and the proceeds will be transferred to the
    Company, (c) the Company will distribute the stock of Cryovac to Grace
    Delaware, (d) Grace Delaware will contribute the stock of the Company to
    New Grace, and (e) Grace Delaware will distribute to its public
    shareholders the stock of New Grace.

         `Parent': Grace Delaware, until such time as Grace Delaware in
    connection with the Packaging Transaction no longer directly or indirectly
    owns all of the stock of the Company, and thereafter, New Grace, except
    that for purposes of Section 12, the term Parent shall include New Grace
    and, until the Release Date, Grace Delaware.

         `Release Date': the date on which the Administrative Agent executes
    the release contemplated by subsection 13.16.

         2.2 Miscellaneous. Section 13 of the Credit Agreement is hereby
amended by adding the following new paragraph to the end of such Section:

         "13.16 Release of Grace Delaware. Promptly after the completion of the
    Packaging Transaction, the Administrative Agent, on behalf of the
    Administrative Agent and the Banks, shall, upon receipt of the written
    request of the Parent or Grace Delaware, execute an acknowledgment that
    Grace Delaware is released from all its obligations under this Agreement
    (including, without limitation, its obligations under the Parent Guarantee)
    provided that the Administrative Agent shall have received a certificate
    dated the date of such request executed by a Responsible Officer of each of

                                       2
<PAGE>

    New Grace and the Company to the effect that (a) each of the
    representations and warranties made by each of the Loan Parties (other than
    Grace Delaware) in or pursuant to Sections 6.1, 6.2, 6.3, 6.5, 6.9, 6.10,
    6.11, 6.12 and 6.13 of this Agreement is true and correct in all material
    respects as of the date of such certificate as if made on and as of such
    date and (b) no Default or Event of Default has occurred and is continuing
    on the date of such certificate after giving effect to the Packaging
    Transaction."


                                  ARTICLE III.
                            CREDIT AGREEMENT WAIVERS

         3.1 Waiver of Covenants. The Banks and the Administrative Agent hereby
waive compliance by the Loan Parties with the provisions of subsection 9.1,
9.2, 9.3 and 9.4 of the Credit Agreement, solely insofar as the steps taken in
connection with the Packaging Transaction might otherwise be deemed to result
in a breach of any of the covenants contained in those subsections; provided
that the Banks and the Administrative Agent shall only waive compliance by the
Loan Parties with the provisions of subsection 9.1 of the Credit Agreement with
respect to the fiscal quarter ending March 31, 1998 and only then if such
subsection would be breached because step (b) of the Packaging Transaction
would have occurred in the fiscal quarter ending March 31, 1998 and step (e) of
the Packaging Transaction would have occurred in the fiscal quarter ending June
30, 1998.

         3.2 Waiver of Certain Defaults. The Banks and the Administrative Agent
hereby agree that the waivers contained in Section 3.1 of this Amendment shall
have effect for purposes of Section 8.2(b), Section 10(c) and Section 10(d) of
the Credit Agreement, and hereby waive application of the provisions of Section
10(i) of the Credit Agreement solely insofar as the steps taken in connection
with the Packaging Transaction might otherwise be deemed to result in a default
under Section 10(i).

                                  ARTICLE IV.
                                 MISCELLANEOUS

         4.1 Effectiveness. This Amendment shall become effective on the
condition that (a) the Administrative Agent shall have received counterparts
hereof, duly executed and delivered by the Company, Grace Delaware, New Grace
and the Banks, (b) the Administrative Agent shall have received a legal opinion
of counsel to the Company, Grace Delaware and New Grace in form and substance
acceptable to the Administrative Agent, and (c) no Default or Event of Default
shall have occurred and be continuing on the date hereof after giving effect to
this Amendment. The date on which all of the above conditions are met shall be
the date of effectiveness of this Amendment (the "Effective Date").

         4.2 New Grace. By signing this Amendment, all of the parties hereto
hereby: (i) acknowledge that as of the Effective Date, New Grace will be a
party to the Credit Agreement, as modified hereby, and, as such, will be bound
by the terms and provisions

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<PAGE>

thereof as if an original party thereto, and (ii) acknowledge and agree that,
commencing with the Effective Date, Grace Delaware and New Grace will be
jointly and severally bound as guarantors under Section 12 of the Credit
Agreement, until Grace Delaware is released in accordance with Section 13.16 of
the Credit Agreement.

         4.3 Continuing Effect of Credit Agreement. This Amendment shall not
constitute an amendment, consent or waiver of any other provision of the Credit
Agreement not expressly referred to herein and, except as provided herein,
shall not be construed as an amendment, consent or waiver to any further or
future action on the part of the Loan Parties that would require a consent or
waiver of the Administrative Agent and/or any of the Banks. Except as expressly
consented to and waived hereby, the provisions of the Credit Agreement are and
shall remain in full force and effect.

         4.4 Counterparts. This Amendment may be executed by one or more of the
parties to this Amendment on any number of separate counterparts, and all of
such counterparts taken together shall be deemed to constitute one and the same
instrument. In addition, this Amendment may be delivered by facsimile
transmission of the relevant signature pages thereof.

         4.5 GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED
AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

         4.6 Expenses. The Company agrees to pay or reimburse the
Administrative Agent for all of its out-of-pocket costs and expenses incurred
in connection with the preparation, negotiation and execution of this
Amendment, including, without limitation, the fees and disbursements of counsel
to the Administrative Agent.

         4.7 Section Headings. The section headings used in this Amendment are
for convenience of reference only and are not to affect the construction hereof
or be taken into consideration in the interpretation hereof.

         4.8 Severability. Any provision of this Amendment which is prohibited
or unenforceable in any jurisdiction shall, as to such jurisdiction, be
ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction, in any such case so
long as the economic or legal substance of the transactions provided for herein
is not affected in any manner adverse to any party.


        [The remainder of this page has intentionally been left blank.]

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<PAGE>

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


                                            W. R. GRACE & CO.-CONN.



                                            By:
                                               --------------------------------
                                               Title:  Senior Vice President




                                            W. R. GRACE & CO.



                                            By:
                                               --------------------------------
                                               Title:  Senior Vice President




                                            GRACE SPECIALTY CHEMICALS,
                                            INC.



                                            By:
                                               --------------------------------
                                               Title:  Senior Vice President

<PAGE>

                                            THE CHASE MANHATTAN BANK, as
                                            Administrative Agent and as
                                              a Bank


                                            By:
                                               --------------------------------
                                               Title:



                                            NATIONSBANK, N.A. (SOUTH)


                                            By:
                                               --------------------------------
                                               Title:



                                            ABN AMRO BANK N.V., NEW YORK
                                            BRANCH


                                            By:
                                               --------------------------------
                                               Title:


                                            By:
                                               --------------------------------
                                               Title:



                                            BANK OF AMERICA NATIONAL
                                            TRUST AND SAVINGS ASSOCIATION


                                            By:
                                               --------------------------------
                                               Title:



                                            BANK OF NEW YORK


                                            By:
                                               --------------------------------
                                            Title:

<PAGE>

                                            THE BANK OF NOVA SCOTIA


                                            By:
                                               --------------------------------
                                            Title:



                                            BARCLAYS BANK PLC


                                            By:
                                               --------------------------------
                                            Title:



                                            CITIBANK, N.A.


                                            By:
                                               --------------------------------
                                            Title:



                                            COMMERZBANK AG, ATLANTA AGENCY


                                            By:
                                               --------------------------------
                                            Title:



                                            CREDIT LYONNAIS ATLANTA AGENCY


                                            By:
                                               --------------------------------
                                            Title:

<PAGE>

                                            CREDIT SUISSE FIRST BOSTON


                                            By:
                                               --------------------------------
                                            Title:


                                            By:
                                               --------------------------------
                                            Title:



                                            DRESDNER BANK AG, NEW YORK AND
                                            GRAND CAYMAN BRANCHES


                                            By:
                                               --------------------------------
                                            Title:


                                            By:
                                               --------------------------------
                                            Title:



                                            FIRST UNION NATIONAL BANK OF FLORIDA


                                            By:
                                               --------------------------------
                                            Title:



                                            MARINE MIDLAND BANK


                                            By:
                                               --------------------------------
                                            Title:

<PAGE>

                                            MORGAN GUARANTY TRUST COMPANY OF
                                            NEW YORK


                                            By:
                                               --------------------------------
                                            Title:



                                            UNION BANK OF SWITZERLAND - NEW YORK


                                            By:
                                               --------------------------------
                                            Title:


                                            By:
                                               --------------------------------
                                            Title: