<PAGE>

                                                                    EXHIBIT 4.05

                          CONSENT AND FOURTH AMENDMENT
                               TO CREDIT AGREEMENT

         This CONSENT AND FOURTH AMENDMENT TO CREDIT AGREEMENT, dated as of
December 31, 2003 (the "CONSENT AND FOURTH AMENDMENT"), is entered into among
NASHUA CORPORATION, a Massachusetts corporation (the "BORROWER"), whose address
is 11 Trafalgar Square, 2nd Floor, Nashua, New Hampshire 03063, FLEET NATIONAL
BANK, a national Banking association ("FLEET") and LASALLE BANK NATIONAL
ASSOCIATION, a national Banking association ("LASALLE", TOGETHER WITH FLEET, THE
"BANKS" AND AS AGENT FOR THE BANKS "AGENT"), whose address is 135 South LaSalle
Street, Chicago, Illinois 60603.

                                R E C I T A L S:

         A.       The Borrower and the Banks entered into that certain Credit
Agreement dated as of March 1, 2002, as amended by that certain First Amendment
to Credit Agreement, dated as of July 15, 2003, that certain Waiver and Second
Amendment to Credit Agreement, dated as of July 24, 2003 and that certain Third
Amendment to Credit Agreement, dated as of September 25, 2003 (as further
amended, restated and modified from time to time, the "CREDIT AGREEMENT").

         B.       At the present time the Borrower requests, and the Banks are
agreeable to, an adjustment to the Funded Debt to EBITDA financial covenant
contained in Section 10.6.2 and consent to the inclusion of certain items within
the definition of Adjusted EBITDA, pursuant to the terms and conditions
hereinafter set forth.

         NOW THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and adequacy of which are hereby
acknowledged, the Borrower and the Banks hereby agree as follows:

                              A G R E E M E N T S:

         1.       RECITALS

         The foregoing Recitals are hereby made a part of this Consent and
Fourth Amendment.

         2.       DEFINITIONS

         Capitalized words and phrases used herein without definition shall have
the respective meanings ascribed to such words and phrases in the Credit
Agreement.

         3.       AMENDMENT TO THE CREDIT AGREEMENT

<PAGE>

         Funded Debt to EBITDA. Section 10.6.2 of the Credit Agreement is hereby
amended by inserting the following provision after the Funded Debt to EBITDA
Ratio chart:

                  "provided, however, that (i) for the Computation Period ended
         December 31, 2003 only, the Funded Debt to EBITDA Ratio shall be
         computed as the Funded Debt to Adjusted EBITDA Ratio, (ii) the Borrower
         shall not thereafter be permitted to use Adjusted EBITDA for any
         subsequent calculation of the Funded Debt to EBITDA Ratio, and (iii)
         for the Computation Period ended December 31, 2003 only, the Funded
         Debt to Adjusted EBITDA Ratio shall not exceed the ratio of 2.75 to
         1.00."

         4.       CONSENT. The Banks party hereto each hereby consent that for
financial covenant compliance for the Computation Period ended December 31, 2003
only, the following items, each recorded in the Fiscal Quarter ended December
31, 2003, shall be included within the definition of Adjusted EBITDA: (i)
severance charges; and (ii) a one-time, non-cash charge for retiree medical
benefits.

         5.       REPRESENTATIONS AND WARRANTIES

         To induce the Banks to enter into this Consent and Fourth Amendment,
the Borrower hereby certifies, represents and warrants to the Banks that:

                  5.1      Organization

         The Borrower is a corporation duly organized, existing and in good
standing under the laws of the Commonwealth of Massachusetts, with full and
adequate corporate power to carry on and conduct its business as presently
conducted. The Borrower is duly licensed or qualified in all foreign
jurisdictions wherein the nature of its activities require such qualification or
licensing. The exact legal name of the Borrower is as set forth in the preamble
of this Consent and Fourth Amendment, and the Borrower currently does not
conduct, nor has it during the last five (5) years conducted, business under any
other name or trade name, except that some of its operations were conducted
under the name Rittenhouse, Rittenhouse Paper Company or Rittenhouse, L.L.C.
prior to 2002. The Borrower will not change its name, its organizational
identification number, its type of organization, its jurisdiction of
organization or other legal structure.

                  5.2      Authorization

         The Borrower is duly authorized to execute and deliver this Consent and
Fourth Amendment and is and will continue to be duly authorized to borrow monies
under the Credit Agreement, as amended hereby, and to perform its obligations
under the Credit Agreement, as amended hereby.

                  5.3      No Conflicts

         The execution and delivery of this Consent and Fourth Amendment and the
performance by the Borrower of its obligations under the Credit Agreement, as
amended

                                       2

<PAGE>

hereby, do not and will not conflict with any provision of law or of the
articles of incorporation of the Borrower or of any agreement binding upon the
Borrower.

                  5.4      Validity and Binding Effect

         The Credit Agreement, as amended hereby, is a legal, valid and binding
obligation of the Borrower, enforceable against the Borrower in accordance with
its terms, except as enforceability may be limited by Bankruptcy, insolvency or
other similar laws of general application affecting the enforcement of
creditors' rights or by general principles of equity limiting the availability
of equitable remedies.

                  5.5      Compliance with Credit Agreement

         The representation and warranties set forth in Section 9 of the Credit
Agreement, as amended hereby, are true and correct with the same effect as if
such representations and warranties had been made on the date hereof, with the
exception that all references to the financial statements shall mean the
financial statements most recently delivered to the Banks and except for such
changes as are specifically permitted under the Credit Agreement. In addition,
the Borrower has complied with and is in compliance with all of the covenants
set forth in the Credit Agreement, as amended hereby, including, but not limited
to, those set forth in Section 10 thereof.

                  5.6      No Event of Default

         As of the date hereof, no Event of Default under Section 12 of the
Credit Agreement, as amended hereby, or event or condition which, with the
giving of notice or the passage of time, or both, would constitute an Event of
Default, has occurred or is continuing.

         6.       CONDITIONS PRECEDENT

         This Consent and Fourth Amendment shall become effective as of the date
above first written after receipt by the Banks of the following documents (and
the date on which all such conditions precedent have been satisfied or waived by
the Banks shall be called the "CONSENT AND FOURTH AMENDMENT EFFECTIVE DATE"):

                  6.1      Consent and Fourth Amendment

         This Consent and Fourth Amendment executed by the Borrower and the
Banks.

                  6.2      Resolutions

         A certified copy of resolutions of the Board of Directors and/or
shareholders of the Borrower authorizing the execution, delivery and performance
of this Consent and Fourth Amendment and the related loan documents.

                  6.3      Other Documents

                                       3

<PAGE>

         Such other documents, certificates and/or opinions of counsel as the
Banks may request.

         7.       GENERAL

                  7.1      Governing Law; Severability

         This Consent and Fourth Amendment shall be construed in accordance with
and governed by the laws of Illinois. Wherever possible each provision of the
Credit Agreement and this Consent and Fourth Amendment shall be interpreted in
such manner as to be effective and valid under applicable law, but if any
provision of the Credit Agreement and this Consent and Fourth Amendment shall be
prohibited by or invalid under such law, such provision shall be ineffective to
the extent of such prohibition or invalidity, without invalidating the remainder
of such provision or the remaining provisions of the Credit Agreement and this
Consent and Fourth Amendment.

                  7.2      Successors and Assigns

         This Consent and Fourth Amendment shall be binding upon the Borrower
and the Banks and their respective successors and assigns, and shall inure to
the benefit of the Borrower and the Banks and the successors and assigns of the
Banks.

                  7.3      Continuing Force and Effect of Loan Documents

         Except as specifically modified or amended by the terms of this Consent
and Fourth Amendment, all other terms and provisions of the Credit Agreement and
the other Loan Documents are incorporated by reference herein, and in all
respects, shall continue in full force and effect. The Borrower, by execution of
this Consent and Fourth Amendment, hereby reaffirms, assumes and binds itself to
all of the obligations, duties, rights, covenants, terms and conditions that are
contained in the Credit Agreement and the other Loan Documents.

                  7.4      Financing Statements

         The Borrower hereby irrevocably authorizes the Banks at any time and
from time to time to file in any jurisdiction any initial UCC financing
statements and/or amendments thereto that (a) describe the Collateral, and (b)
contain any other information required by part 5 of Article 9 of the UCC for the
sufficiency or filing office acceptance of any financing statement or amendment.

                  7.5      References to Credit Agreement

         Each reference in the Credit Agreement to "this Agreement",
"hereunder", "hereof", or words of like import, and each reference to the Credit
Agreement in any and all instruments or documents delivered in connection
therewith, shall be deemed to refer to the Credit Agreement, as amended hereby.

                  7.6      Expenses

                                       4

<PAGE>

         The Borrower shall pay all costs and expenses in connection with the
preparation of this Consent and Fourth Amendment and other related loan
documents, including, without limitation, reasonable attorneys' fees and time
charges of attorneys who may be employees of the Banks or any affiliate or
parent of the Banks. The Borrower shall pay any and all stamp and other taxes,
UCC search fees, filing fees and other costs and expenses in connection with the
execution and delivery of this Consent and Fourth Amendment and the other
instruments and documents to be delivered hereunder, and agrees to save the
Banks harmless from and against any and all liabilities with respect to or
resulting from any delay in paying or omission to pay such costs and expenses.

                  7.7      Counterparts

         This Consent and Fourth Amendment may be executed in any number of
counterparts, all of which shall constitute one and the same agreement.

                            [Signature Page Follows]

                                       5

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Consent and
Fourth Amendment to Credit Agreement as of the date first above written.

WITNESS:                              NASHUA CORPORATION

/s/ Margaret M. Callan                By:  /s/ John L. Patenaude
                                      Name: John L. Patenaude
                                      Title:    Vice President - Finance, Chief
                                                Financial Officer and Treasurer

WITNESS:                              LASALLE BANK NATIONAL
                                      ASSOCIATION, as Agent
/s/ Signature Illegible

                                      By: /s/ Brian Sullivan
                                      Name:  Brian Sullivan
                                      Title: Vice President

WITNESS:                              LASALLE BANK NATIONAL
                                      ASSOCIATION, as Issuing Bank and as a
                                      Bank
/s/ Signature Illegible
                                      By: /s/ Brian Sullivan
                                      Name:  Brian Sullivan
                                      Title: Vice President

WITNESS:                              FLEET NATIONAL BANK, as a Bank

/s/ Signature Illegible               By:  /s/ Kenneth R. Sheldon
                                      Name: Kenneth R. Sheldon
                                      Title: Vice President