BANK OF BOSTON
-------------


                                        March 19, 1997
Mr. Moosa E. Moosa
Chief Financial Officer
Chemfab Corporation
7O1 Daniel Webster Highway
Merrimack, New Hampshire 03054

Dear Mr. Moosa:

We are pleased to confirm that The First National Bank of Boston (the "Bank")
holds available an informal unsecured line of credit in an aggregate amount of
$1,000,000.00 for Chemfab Corporation, a Delaware corporation (the "Company"),
which shall consist of revolving ("Revolving Loans") and Letters of Credit
(hereinafter defined) subject to the terms set herein.

1.   Revolving Loans. Each Revolving Loan made under this Agreement must be in a
     ---------------
     minimum amount of $50,000.00 (provided that any request for a Money Market
     Loan shall be in a minimum amount of $1,000,000.00) or any larger amount
     which is integral multiple of $50,000.00; provided that aggregate loans
     outstanding under this Agreement shall not exceed $1,000,000.00 at any
     time. Requests by the Company for Revolving Loans must be received by the
     Bank no later than 12:00 noon (Boston time) on the day of the requested
     loan. Promptly upon receipt of such notice, the Bank may, in its
     discretion, make the requested Revolving Loans by crediting the proceeds
     thereof to the demand deposit account of the Company maintained with the
     Bank.

2.   Letters of Credit. Subject to all the terms and conditions of this
     -----------------
     Agreement, the Bank may, in its discretion, issue for the account of the
     Company one or more irrevocable standby letters of credit having expiration
     dates not later than 365 days from the date of the issuance (the "Letters
     of Credit"). Letter of Credit Exposure plus the aggregate Revolving Loans
                                            ----
     outstanding shall not at any time exceed $1,000,000.00. "Letter of Credit
     Exposure" means, at any date, the sum of (a) the aggregate face amount of
     all drafts that may then or thereafter be presented by beneficiaries under
     all Letters of Credit then outstanding plus (b) the aggregate face amount
                                            ----
     of all drafts that the Bank has previously accepted under Letters of Credit
     but has not paid.


         THE FIRST NATIONAL BANK OF BOSTON, Boston, Massachusetts 02106


     The Company may request a Letter of Credit to be issued by providing to
     the Bank a notice which is actually received not less than five days prior
     to the requested issuance date for such Letter of Credit specifying (a)
     the amount of the requested Letter of Credit, (b) the beneficiary thereof,
     (c) the requested closing date and (d) the principal terms of the text for
     such Letter of Credit. Each Letter of Credit and each draft accepted under
     a Letter of Credit shall be in such form and minimum amount, and shall
     contain such terms as the Bank shall request in its sole discretion. As a
     condition to the issuance of any Letter of Credit the Company will provide
     the Bank with a signed application and such other documents relating to
     the issuance of letters of credit as are customarily required by the Bank.

3.   Evidence of lndebtedness. All Revolving Loans (each as defined below) will
     -----------------------
     be evidenced by a promissory note (the "Note") substantially in the form
     attached hereto as Exhibit I. The Company hereby authorizes the Bank to
     record each loan and the corresponding information on the schedule forming
     part of the applicable Note, and, absent manifest error, this record shall
     be conclusive and binding.

4.   Interest Rates. (a) Subject to the terms and conditions hereof, the Company
     ---------------
     may elect in its request for a Revolving Loan to have interest thereon
     accrue at either of the following interest rate options:

     (i)  a rate per annum equal to the higher of (x) the rate of interest
          announced from time to time by the Bank at its head office as its Base
          Rate, or (y) the sum of 1/2 % plus the overnight Federal Funds Rate
          (an "Alternate Base Rate Loan"); or

     (ii) a rate quoted by the Bank in its sole discretion (it being understood
          that the Bank is under no obligation to quote such rate) to the
          Company as the fixed rate of interest at which it is willing to make a
          "money market" advance to the Company in the amount and for the period
          of the requested loan (a "Money Market Loan").

     Money Market Loans may be requested for interest periods of up to 90 days.
     In the event that the Company fails to specify an interest period in its
     request for a loan, the interest period for Money Market Loans shall be
     deemed to be 30 days. Interest on each loan shall be calculated on the
     basis of a 360-day year for the actual number of days elapsed. The Federal
     Funds Rate shall mean, for any day (i) the rate equal to the weighted
     average of the rates on overnight federal funds transactions with members
     of the Federal Reserve Bank arranged by federal funds brokers, as such
     weighted average is published for such day (or, if such day is not a
     banking day, for the immediately preceding banking day) by the Federal
     Reserve Bank of New York or (ii) if such rate is not published for such
     banking day, the average of the quotations for such day on such
     transactions received by the Bank from three federal funds brokers of
     recognized standing selected by the Bank.

           (b)  Interest on Revolving Loans which are Alternate Base Rate Loans
     shall be payable on the last day of each fiscal quarter of the Company.
     Interest on Revolving Loans which are Money Market Loans shall be payable
     on the same day as the principal amount thereunder is due. The Company will
     pay to the Bank, on the date of issuance of each Letter of Credit under
     this Agreement, a Letter of Credit fee equal to one percent (1 %) of the
     face amount of such Letter of Credit. The Company will pay to the Bank
     customary service charges and expenses for its services in connection with
     the Letter of Credit at the times and in the amounts from time to time in
     effect in accordance with its general rate structure, including fees and
     expenses relating to issuance, amendment, negotiation, cancellation and
     similar operations.

5.   Payments and Repayments. Revolving Loans which are Alternate Base Rate
     ------------------------
     Loans shall be payable on demand by the Bank, and Money Market Loans shall
     be payable on the earlier of demand or the last day of the interest period
     applicable thereto. The Company may prepay Alternate Base Rate Loans, in
     whole or in part, at any time and without prepayment penalties, but
     prepayments of Money Market Loans will not be permitted. If the Company for
     any reason makes any payment with respect to a Money Market Loan before its
     maturity (whether by acceleration or otherwise), or fails to borrow a Money
     Market Loan requested by the Company, the Company will be required to pay
     any costs, losses (including lost profits) or liabilities incurred by the
     Bank as a result thereof, including any losses incurred in obtaining,
     liquidating or employing deposits with reference to which the rate of
     interest for such loan was determined, upon presentation by the Bank of a
     statement in the amount and setting forth the Bank's calculation thereof,
     which statement shall be deemed true and correct absent manifest error.
     This Agreeenent and the Note evidences your promise to pay all borrowings
     hereunder with interest on their respective maturity or due dates.

     6.   Availability of Loans. The availability of loans under this facility
          ---------------------
     is subject to the discretion of the Bank, and nothing in this Agreement
     shall be construed as a commitment of the Bank to lend or to quote rates
     on some or all maturities. In addition, the following events shall
     constitute a default ("Defaults"): (a) there shall have occurred a
     material adverse change in the assets, liabilities, financial condition,
     business operations or prospects of the Company since the date, hereof; or
     (b) any substantive changes in government regulations or monetary
     policies. Upon a Default, all obligations of the Company hereunder shall
     become immediately due and payable without notice or demand. All rights
     and remedies of the Lender are cumulative and exclusive of any rights or
     remedies provided by law or in equity or any other agreement, and may be
     exercised separately or concurrently.

     If this letter accurately sets forth our understanding with respect to the
subject matter hereof, please indicate that the Company will be bound by
executing and dating (the "Effective Date") this letter in the space provided
and returning it to us.

                                   Sincerely,

                              The First National Bank of Boston


                             By: /s/ Andrew T. Fay
                             -----------------------
                               Name: Andrew T. Fay
                               Title: Vice President

Acknowledged and Accepted as of March 19, 1997:

Chemfab Corporation


By: /s/ Moosa E. Moosa
----------------------
      Name:    Moosa E. Moosa
      Title:   Vice President, Finance and Chief Financial Officer




                                 EXHIBIT 1


                         FORM OF DEMAND PROMISSORY NOTE


PN- __________________
                                                            MARCH 19, 1997

  FOR VALUE RECEIVED, the undersigned, Chemfab Corporation, a Delaware
corporation (the "Borrower"), hereby promises to pay to The First National
Bank of Boston (the "Lender") or order, on the earlier of (i) the
occurrence of a Default or (ii) written DEMAND as set forth in the Letter
Agreement (defined below), the aggregate unpaid principal amount of all
loans made by the Lender to the Borrower pursuant to the Letter Agreement.
The Borrower promises to pay daily interest from the date hereof, computed
as provided in such Letter Agreement, on the aggregate principal amount of
such loans from time to time unpaid at the per annum rate applicable to
such unpaid principal amount as provided in such Letter Agreement, such
interest being payable at the times specified in such Letter Agreement,
except that all accrued interest shall be paid at the stated or accelerated
maturity hereof or upon the prepayment in full hereof.

   Payments hereunder shall be made to The First National Bank of Boston, 100
Federal Street, Boston, Massachusetts 02110 on or before 2:00 p.m. on the due
date thereof.

   All loans made by the Lender pursuant to the Letter Agreement referred to 
below and all repayments of the principal thereof shall be recorded by the 
Lender and, prior to any transfer hereof, appropriate notations to evidence the 
foregoing information with respect to each such loan then outstanding shall be 
endorsed by the Lender on the schedule attached hereto or on a continuation of 
such schedule attached to and made a part hereof; provided, however, that the 
                                                  --------  -------
failure of the Lender to make any such recordation or endorsement shall not 
affect the obligations of the Borrower under this Note, such Letter Agreement 
or under any other related document.

   This Note evidences borrowings under, and is entitled to the benefits of, and
is subject to the provisions of, the Letter Agreement dated as of March 19, 1997
as from time to time in effect (the "Letter Agreement"), between the Borrower 
and the Lender. The principal of this Note is prepayable in the amounts and 
under the circumstances set forth in the Letter Agreement, and may be prepaid in
whole or from time to time in part, all as set forth in the Letter Agreement. 
Terms defined in the Letter Agreement and not otherwise defined herein are used 
herein with the meanings so defined.

   In case a Default shall occur, or upon written DEMAND, the entire principal 
of this Note may become or be declared due and payable in the manner and with 
the effect provided in the Letter Agreement. To the extent permitted by 
applicable law, upon and after the occurrence of a Default, interest on 
principal and overdue interest shall, at the option of the Lender, be payable 
on demand at a rate per annum equal to 2% above the rate otherwise payable 
hereunder.

   The Lender is hereby authorized at any time and from time to time, without
notice to the undersigned (any such notice being expressly waived by the
undersigned) and to the fullest extent permitted by law, to set off and apply
any and all deposits (general or special, time or demand, provisional or final)
and other sums credited by or due from the Lender to the undersigned or subject
to withdrawal by the undersigned against the obligations of the undersigned,
although such obligations may be contingent or unmatured.

   The undersigned agrees to indemnify the Lender and hold it harmless from and
against any transfer taxes, documentary taxes, assessments or charges made by
any governmental authority by reason of the execution, delivery and performance
of this Note.

   The undersigned will pay on demand all expenses of the Lender in connection 
with the preparation, administration, default, collection, waiver or amendment 
of the obligations or in connection with the Lender's exercise, preservation or
enforcement of any of its rights, remedies or options thereunder, including
without limitation, fees of outside legal counsel or the allocation costs of in-
house legal counsel, accounting, consulting, brokerage or other similar
professional fees or expenses, and any fees or expenses associated with any
travel or other costs relating to any appraisals or examinations conducted in
connection with the obligations or any collateral therefor, and the amount of
all such expenses shall, until paid, bear interest at the rate applicable to
principal hereunder (including any default rate) and be obligation secured by
any such collateral.

   THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS (OTHER THAN THE CONFLICT OF
LAWS RULES).

   The Borrower hereby waives presentment, demand, notice, protest and all 
other demands and notices in connection with the delivery, acceptance, 
performance and enforcement of this Note, except as specifically otherwise 
provided in the Letter Agreement, and assent to extensions of time of payment, 
or forbearance or other indulgence without notice.

   JURY WAIVER. THE LENDER (BY ITS ACCEPTANCE OF THIS NOTE) AND
THE UNDERSIGNED AGREE THAT NEITHER OF THEM NOR ANY ASSIGNEE
OR SUCCESSOR SHALL (A) SEEK A JURY TRIAL IN ANY LAWSUIT, PROCEEDING,
COUNTERCLAIM OR ANY OTHER ACTION BASED UPON, OR ARISING OUT OF, THIS NOTE, ANY
RELATED INSTRUMENTS OR THE DEALINGS OR THE RELATIONSHIP BETWEEN OR AMONG ANY OF
THEM OR (B) SEEK TO CONSOLIDATE ANY SUCH ACTION WITH ANY OTHER ACTION IN WHICH A
JURY TRIAL CANNOT BE OR HAS NOT BEEN WAIVED. THE PROVISIONS OF THIS PARAGRAPH
SHALL BE SUBJECT TO NO EXCEPTIONS. NEITHER THE LENDER NOR THE UNDERSIGNED HAS
AGREED WITH OR REPRESENTED TO THE OTHER THAT THE PROVISIONS OF THIS PARAGRAPH
WILL NOT BE FULLY ENFORCED IN ALL INSTANCES.

                              CHEMFAB CORPORATION


                              By: /s/ Moosa E. Moosa
                              -----------------------
                                      Name:Moosa E. Moosa
                                      Title: Vice President, Finance and
                                             Chief Financial Officer

                                      March 19, 1997


<TABLE>
<S><C>



                      NOTE SCHEDULE TO PROMISSORY NOTE OF
                              CHEMFAB CORPORATION
                              DATED ____________, 1997


                                                           Date and Amount
                                                         --------------------
              Principal Amount                               of Payment
              -----------------                              ----------
Date of  Loan     of Loan      Maturity Date  Interest Rate   Received   Notation Made By
-------------     -------      -------------  -------------   --------   ----------------

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

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

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

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

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

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

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

</TABLE>