<PAGE>   1

                                                                   Exhibit 10.18


                CONSENT AND SEVENTH AMENDMENT TO CREDIT AGREEMENT

         THIS CONSENT AND SEVENTH AMENDMENT (this "Amendment") to CREDIT
AGREEMENT among SPINNAKER COATING, INC., a Delaware corporation, formerly known
as Brown-Bridge Industries, Inc. ("Coating"), ENTOLETER, INC., a Delaware
corporation ("Entoleter"), SPINNAKER COATING-MAINE, INC., a Delaware corporation
("SCM" and, together with Coating and Entoleter, the "Borrowers"), SPINNAKER
INDUSTRIES, INC., a Delaware corporation (the "Guarantor" and, together with the
Borrowers, the "Credit Parties"), the financial institutions from time to time
party thereto as lenders (the "Lenders"), and TRANSAMERICA BUSINESS CAPITAL
CORPORATION (as successor of Transamerica Business Credit Corporation), as agent
(in such capacity the "Agent") for the Lenders, is made as of May 15, 2001 among
the Credit Parties and the undersigned Lenders.

                              W I T N E S S E T H :

         WHEREAS, the Credit Parties, the Lenders and the Agent are parties to
the Credit Agreement, dated as of August 9, 1999 (as amended, restated or
otherwise modified from time to time prior to the date of effectiveness of this
Amendment, the "Credit Agreement"; capitalized terms used herein shall have the
meanings assigned to such terms in the Credit Agreement unless otherwise defined
herein);

         WHEREAS, the Credit Parties have advised Lenders that SCM is planing to
close its facility located at Westbrook, Maine (the "Westbrook Facility"), sell
certain of its assets and subsequently cease all of its business operations. The
Credit Parties, therefore, have requested that the Lenders (i) consent to the
sale of certain assets of SCM and the subsequent cessation of all business
operations of SCM; and (ii) make certain amendments to the Credit Agreement;

         WHEREAS, the Lenders are agreeable to such request, but only on the
terms and subject to the conditions set forth herein.

         NOW, THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the parties hereto hereby agree as follows:

         1. CONSENT UNDER CREDIT AGREEMENT.

         (a) Pursuant to Section 7.2(e) of the Credit Agreement and subject to
the conditions set forth herein and in Section 3 hereof, the Agent and the
Lenders hereby consent to (a) the sale by SCM of the "Assets" (as defined in
Section 2.1 of the Avery Purchase Agreement (as defined below)) located at the
Westbrook Facility to Avery Dennison Corporation ("Avery"), free of Liens of the
Agent and the Lenders, for Net Cash Proceeds of at least $1,500,000 (the "SCM
Asset Sale") pursuant to the terms of that certain Asset Purchase Agreement
dated as of May 14, 2001 by and between SCM and Avery (the "Avery Purchase
Agreement"); and (b) the cessation of all business operations of SCM on or prior
to December 31, 2001, provided that Agent shall have received 100% of the Net
Cash Proceeds from the SCM Asset Sale.

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         (b) The CIT Group/Business Credit, Inc. hereby authorizes Agent to
execute and deliver to SCM a Consent and Release Letter ("Consent and Release
Letter") and appropriate UCC partial release statements and patents and
trademarks lien releases to facilitate the release of the Agent's and the
Lenders' Liens upon the "Assets" (as defined in Section 2.1 of the Avery
Purchase Agreement) upon consummation of the SCM Asset Sale.

         2. AMENDMENT TO CREDIT AGREEMENT. Subject to the satisfaction of the
conditions to effectiveness set forth in Section 3 hereof, the Credit Parties
and the Lenders agree to amend the Credit Agreement effective as of March 30,
2001 as follows:

         (a) The fourth Recitals and Section 2 of Amendment No. 6 is hereby
amended and restated to read in its entirety as follows:

                  "WHEREAS, on or about March 23, 2001 Transamerica Business
         Credit Corporation has assigned all of its rights and obligations under
         the Credit Agreement, the Revolving Notes and the other Credit
         Documents to TCFC I and subsequently on or about March 26, 2001 TCFC I
         has assigned all of its rights and obligations under the Credit
         Agreement, the Revolving Notes and the other Credit Documents to
         Transamerica Business Capital Corporation (the "Assignments").

                  2. CONSENT AND OMNIBUS AMENDMENT TO CREDIT AGREEMENT. Each
         Credit Party and Lender hereby consents to the Assignments and agrees
         to take all actions and execute and deliver all instruments and
         documents reasonably requested by the Agent to evidence and confirm the
         assignment and delegation of all rights and obligations under each of
         the Credit Documents of Transamerica Business Credit Corporation to
         Transamerica Business Capital Corporation. Subject to the satisfaction
         of the conditions to effectiveness set forth in Section 3 hereof, the
         Credit Parties and the Lenders agree that each of the Credit Documents
         is hereby amended to cause all references to Transamerica Business
         Credit Corporation to be deemed to be references to Transamerica
         Business Capital Corporation."

         (b) Section 1.1 of the Credit Agreement is hereby amended to add the
following new defined terms in alphabetical order:

                  ""Amendment No. 7" means that certain Consent and Seventh
         Amendment to Credit Agreement dated as of May 15, 2001 by and among the
         Credit Parties, the Lenders and the Agent.

                  "Amendment No. 7 Date" means May 15, 2001.

                  "Impaired Assets Adjustment" means a one-time non-cash charge
         incurred in connection with the revaluation of the assets of SCM
         associated with the closure of SCM's facility in Westbrook, Maine.


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<PAGE>   3

                  "SCM Asset Sale" means the sale of certain assets of SCM to
         Avery Dennison Corporation, a Delaware corporation ("Avery") for Net
         Cash Proceeds of at least $1,500,000 pursuant to the terms of that
         certain Asset Purchase Agreement dated as of May 14, 2001 by and
         between SCM and Avery ("Avery Purchase Agreement").

                  "SCM Supplemental Asset Sale" means (i) any sale or other
         disposition of assets of SCM (other than the SCM Asset Sale), not
         constituting Eligible Accounts and Eligible Inventory of SCM, occurring
         in connection with the closure of SCM's Westbrook facility, and (ii)
         the receipt of the "Commissions" as defined in Section 3.3 of the Avery
         Purchase Agreement."

         (c) The definition of "Line of Credit" in Section 1.1 of the Credit
Agreement is hereby amended and restated to read in its entirety as follows:

                  "Line of Credit" means the aggregate revolving line of credit
         extended by the Lenders to the Borrowers for Revolving Loans and
         Letters of Credit pursuant to and in accordance with the terms of this
         Credit Agreement, in an amount not to exceed the Maximum Line of
         Credit, as such amount may be reduced from time to time in accordance
         with this Credit Agreement. As used herein, the "Maximum Line of
         Credit" shall mean (i) $40,000,000 for the period from the Closing Date
         through, but not including, the Amendment No. 7 Date; (ii) $35,000,000
         for the period from the Amendment No. 7 Date through, but not
         including, January 1, 2002; and (iii) $30,000,000 for the period from
         January 1, 2002 through, but not including, the Expiration Date."

         (d) The definition of "SCM Line of Credit" in Section 1.1 of the Credit
Agreement is hereby amended and restated to read in its entirety as follows:

                  "SCM Line of Credit" means the aggregate revolving line of
         credit extended by the Lenders to SCM for Revolving Loans and Letters
         of Credit pursuant to and in accordance with the terms of this Credit
         Agreement, in an amount not to exceed the Maximum SCM Line of Credit,
         as such amount may be reduced from time to time in accordance with this
         Credit Agreement. As used herein, the "Maximum SCM Line of Credit"
         shall mean (i) $15,000,000 for the period from the Closing Date
         through, but not including, the Amendment No. 7 Date; (ii) $10,000,000
         (without any further reduction for the SCM Asset Sale and any SCM
         Supplemental Asset Sale which, when taken together, generate Net Cash
         Proceeds not exceeding $5,000,000) for the period from the Amendment
         No. 7 Date through, but not including, January 1, 2002; and (iii)
         $5,000,000 (without any further reduction for any SCM Supplemental
         Asset Sale which generates Net Cash Proceeds not exceeding $5,000,000)
         for the period from January 1, 2002 through, but not including, the
         Expiration Date."



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         (e) Section 2.9(d) of the Credit Agreement is hereby amended as
follows:

                  a. The first parentheses in the first sentence of Section
         2.9(d) of the Credit Agreement are hereby amended and restated to read
         in its entirety as follows:

                  "(other than the Central Sale, the SCM Asset Sale and any SCM
         Supplemental Asset Sale)"

                  b. The following words are hereby added to the fourth sentence
         of Section 2.9(d) of the Credit Agreement immediately following the
         words "Any reduction of the Line of Credit":

                  "(other than in respect of the SCM Asset Sale and any SCM
         Supplemental Asset Sale)"

         c. Section 2.9(d) is hereby amended by adding the following sentences
immediately following the fourth sentence thereof:

                  "All Net Cash Proceeds from the SCM Asset Sale and/or any SCM
         Supplemental Asset Sale shall be immediately paid to the Agent to be
         applied to repay the outstanding Revolving Loans, which amount may be
         reborrowed subject to the conditions set forth in Section 5.2 hereof,
         and all Net Cash Proceeds from the SCM Asset Sale and/or any SCM
         Supplemental Asset Sale shall be applied as mandatory reduction of the
         Commitments, the Line of Credit and the SCM Line of Credit. Such
         reduction of the Commitments in respect of the SCM Asset Sale and/or
         any SCM Supplemental Asset Sale shall reduce the Commitment of each
         Lender proportionately by its Proportionate Share of the amount of such
         reduction. After payment in full of all Revolving Loans of SCM, all Net
         Cash Proceeds (including the "Commissions" as defined in Section 3.3 of
         the Avery Purchase Agreement") from the sale or other disposition of
         any remaining assets of SCM including, without limitation, any
         Accounts, Inventory, Equipment, general intangibles or other property
         of SCM, shall be applied to repay the Revolving Loans of Coating, which
         amount may be reborrowed by Coating subject to the conditions set forth
         in Section 5.2 hereof."

         (f) Item (C) at the end of Section 7.1(b)(i) is hereby amended and
restated to read in its entirety as follows:

                  "(C) attached thereto (i) in respect of SCM a current aging of
         Accounts, Inventory collateral report, a loan activity report and cash
         flow projections, in each case in form and substance acceptable to
         Agent; and (ii) such other information as the Agent may reasonably
         request."

         (g) Section 7.2(b)(vii) is hereby amended and restated to read in its
entirety as follows:

                  "(vii) Indebtedness evidenced by the Intercompany Subordinated
         Notes owing by one Borrower or the Guarantor to another Borrower or the
         Guarantor; provided that (A) such Indebtedness is used only for general
         corporate purposes,


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         (B) such Indebtedness is evidenced by one or more promissory notes
         subordinated to the payment of the Obligations and otherwise in form
         and substance satisfactory to the Agent, (C) such promissory notes are
         pledged to the Agent for the ratable benefit of the Lenders pursuant to
         documentation in form and substance satisfactory to the Agent and (D)
         such notes are delivered to the Agent with note powers executed in
         blank; further provided that from and after the Amendment No. 7 Date,
         no additional intercompany loans may be made by any Borrower or
         Guarantor to SCM;"

         (h) The second proviso appearing at the end of Sections 7.2(t) of the
Credit Agreement is hereby amended and restated to read in its entirety as
follows:

                  "provided, further, that when computing Consolidated Net Worth
         for all testing periods from and after October 1, 2000 through and
         including June 30, 2002, the amount of Consolidated Net Worth shall be
         increased by the aggregate amount of Permitted Restructuring Charges
         (net of taxes) and/or Impaired Assets Adjustment (net of taxes)
         actually incurred during such testing period which have had, without
         duplication, the direct effect of reducing the Credit Parties'
         Consolidated Net Worth for such testing period."

         (i) The proviso appearing at the end of Sections 7.2(u) of the Credit
Agreement is hereby amended and restated to read in its entirety as follows:

                  "; provided, however, that in computing the Consolidated Fixed
         Charge Coverage Ratio for all testing periods from and after October 1,
         2000 through and including June 30, 2002, the amount of Adjusted EBITDA
         for any such testing period shall be increased by the sum of (x) the
         amount of the Permitted Restructuring Charges and/or Impaired Assets
         Adjustment actually incurred during such testing period which have had,
         without duplication, the direct effect of reducing the Credit Parties'
         consolidated Specified Net Income and (y) the amount of the Capital
         Infusion actually received by the Borrowers during such testing
         period."

         (j) Schedule I to the Credit Agreement is hereby amended and restated
and replaced by Schedule I attached hereto.

         3. CONDITIONS TO EFFECTIVENESS. This Amendment shall become effective
as of March 30, 2001, upon satisfaction of the following conditions:

         (a) the Agent shall have received this Amendment and the Consent and
Release Letter, duly executed by each of the Credit Parties and the Required
Lenders;

         (b) the Agent shall have received a secretary's or assistant
secretary's certificate of each Credit Party regarding the incumbency of each of
the officers authorized to sign this Amendment and certifying and attaching the
board resolutions authorizing the execution, delivery and performance of this
Amendment;


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<PAGE>   6

         (c) each of the representations and warranties set forth in Section 3
hereof shall be true and correct in all respects; and

         (d) Agent shall have received and deemed satisfactory final copies of
all documents and agreements evidencing or governing the SCM Asset Sale,
including, but not limited to, the Avery Purchase Agreement.

         4. REPRESENTATIONS AND WARRANTIES OF CREDIT PARTIES. Each Credit Party
represents and warrants that:

         (a) the execution, delivery and performance by such Credit Party of
this Amendment have been duly authorized by all necessary corporate action and
this Amendment is a legal, valid and binding obligation of such Credit Party
enforceable against such Credit Party in accordance with its terms, except as
the enforcement thereof may be subject to (i) the effect of any applicable
bankruptcy, insolvency, reorganization, moratorium or similar law affecting
creditors' rights generally and (ii) general principles of equity (regardless of
whether such enforcement is sought in a proceeding in equity or at law);

         (b) each of the representations and warranties contained in the Credit
Agreement is true and correct in all material respects on and as of the date
hereof as if made on the date hereof, except to the extent that such
representations and warranties expressly relate to an earlier date; and

         (c) no Change of Control or other Event of Default has occurred or
remains outstanding as of the date hereof.

         5. FEES AND EXPENSES. The Credit Parties shall pay for all of the
reasonable costs and expenses incurred by the Agent in connection with the
transactions contemplated by this Amendment, including, without limitation, the
reasonable fees and expenses of counsel to the Agent. The Credit Parties
acknowledge and agree that the Agent may charge any fees and all such costs and
expenses which may be owing to the Agent under this Amendment and/or any other
Credit Document to such of the Borrowers' Loan Accounts as Agent may elect in
its discretion.

         6. MISCELLANEOUS.

         (a) Except as expressly amended herein, all of the terms and provisions
of the Credit Agreement and the other Credit Documents are ratified and
confirmed in all respects and shall remain in full force and effect. Each Credit
Party hereby acknowledges and agrees that there is no defense, setoff or
counterclaim of any kind, nature or description to the Obligations or the
payment thereof when due.

         (b) Upon the effectiveness of this Amendment, all references in the
Credit Documents to the Credit Agreement shall mean the Credit Agreement as
amended by this Amendment and all references in the Credit Agreement to "this
Agreement," "hereof," "herein," or similar terms, shall mean and refer to the
Credit Agreement as amended by this Amendment.


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<PAGE>   7
         (c) The execution, delivery and effectiveness of this Amendment shall
not, except as expressly provided herein, operate as an amendment to or waiver
of any right, power or remedy of the Agent or any Lender under any of the Credit
Documents, or constitute an amendment or waiver of any provision of any of the
Credit Documents.

         (d) This Amendment may be executed by the parties hereto individually
or in combination, in one or more counterparts, each of which shall be an
original and all of which shall constitute one and the same agreement. This
Amendment may be executed and delivered by telecopier with the same force and
effect as if the same were a fully executed and delivered original manual
counterpart.

         (e) This Amendment shall constitute a Credit Document.

         7. GOVERNING LAW. THE VALIDITY, INTERPRETATION AND ENFORCEMENT OF THIS
AMENDMENT SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW YORK WITHOUT GIVING
EFFECT TO THE CONFLICTS OF LAW PRINCIPLES THEREOF (OTHER THAN SECTION 5-1401 OF
THE NEW YORK GENERAL OBLIGATIONS LAW).


                            [SIGNATURE PAGE FOLLOWS]


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<PAGE>   8
         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered by their respective duly authorized officers.


                                 BORROWERS:


                                 SPINNAKER COATING, INC.,
                                 formerly known as Brown-Bridge Industries, Inc.

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


                                 SPINNAKER COATING-MAINE, INC.

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


                                 ENTOLETER, INC.

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



                                 GUARANTOR:

                                 SPINNAKER INDUSTRIES, INC.

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






      [Signature Page to Consent and Seventh Amendment to Credit Agreement]
                                       S-1


<PAGE>   9


                                LENDERS:

                                TRANSAMERICA BUSINESS CAPITAL CORPORATION
                                (as successor of Transamerica Business
                                Credit Corporation)

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



                                 THE CIT GROUP/BUSINESS CREDIT, INC.

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






      [Signature Page to Consent and Seventh Amendment to Credit Agreement]
                                       S-2


<PAGE>   10
                                   SCHEDULE 1

                    LENDERS, LENDING OFFICES AND COMMITMENTS

 FROM AND AFTER THE AMENDMENT NO. 7 DATE THROUGH, BUT EXCLUDING JANUARY 1, 2002

<TABLE>
<CAPTION>
                                          Domestic and Eurodollar
Lender                                         Lending Office                    Commitment
------                                         --------------                    ----------
<S>                                      <C>                                     <C>
Transamerica Business Capital             9399 West Higgins Road
Corporation                               Suite 600                              $26,250,000
                                          Rosemont, Illinois  60018

The CIT Group/Business Credit, Inc.       5420 LBJ Freeway                       $8,750,000
                                          Suite 200
                                          Dallas, Texas  75240

                                          Total Commitments                      $35,000,000
</TABLE>


   FROM AND AFTER JANUARY 1, 2002 THROUGH, BUT EXCLUDING THE EXPIRATION DATE:

<TABLE>
<CAPTION>
                                          Domestic and Eurodollar
Lender                                         Lending Office                    Commitment
------                                         --------------                    ----------
<S>                                       <C>                                    <C>
Transamerica Business Capital             9399 West Higgins Road
Corporation                               Suite 600                              $22,500,000
                                          Rosemont, Illinois  60018

The CIT Group/Business Credit, Inc.       5420 LBJ Freeway                       $7,500,000
                                          Suite 200
                                          Dallas, Texas  75240

                                          Total Commitments                      $30,000,000
</TABLE>


                                     Sch.-I