JOINT FILING AGREEMENT

                  The undersigned hereby agree, pursuant to Rule 13d-1(k) of the
Securities Exchange Act of 1934, as amended, to file joint statements on
Schedule 13D and amendments thereto pertaining to their beneficial ownership of
shares of common stock, stated value $25/48 each, of Hercules Incorporated, a
Delaware corporation, and that this joint filing agreement may be included as an
Exhibit to such joint filing.

                  This joint filing agreement may be terminated for any reason
by any party hereto immediately upon the personal delivery or facsimile
transmission of notice to that effect to the other parties hereto.

                  This joint filing agreement may be executed in one or more
counterparts, each of which together shall be deemed to be an original
instrument, but all of such counterparts together shall constitute but one
agreement.







<PAGE>


                                   SIGNATURES

                  IN WITNESS WHEREOF, this joint filing agreement has been duly
executed and delivered as of July 15, 2003.




                                 ISP INVESTCO LLC
                                 By:  International Specialty Holdings Inc.,
                                 its Sole Member

                                 By: /s/ Richard A. Weinberg
                                     -------------------------------------------
                                     Richard A. Weinberg
                                     Executive Vice President, General Counsel
                                     and Secretary



                                 INTERNATIONAL SPECIALTY HOLDINGS INC.


                                 By: /s/ Richard A. Weinberg
                                     -------------------------------------------
                                     Richard A. Weinberg
                                     Executive Vice President, General Counsel
                                     and Secretary



                                 INTERNATIONAL SPECIALTY PRODUCTS INC.


                                 By: /s/ Richard A. Weinberg
                                     -------------------------------------------
                                     Richard A. Weinberg
                                     Executive Vice President, General Counsel
                                     and Secretary


                                     /s/ Samuel J. Heyman
                                     -------------------------------------------
                                     SAMUEL J. HEYMAN


                                     /s/ Sunil Kumar
                                     -------------------------------------------
                                     SUNIL KUMAR



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<PAGE>

                                     /s/ Gloria Schaffer
                                     -------------------------------------------
                                     GLORIA SCHAFFER



                                     /s/ Raymond S. Troubh
                                     -------------------------------------------
                                     RAYMOND S. TROUBH



                                     /s/ Harry Fields
                                     -------------------------------------------
                                     HARRY FIELDS



                                     /s/ Anthony T. Kronman
                                     -------------------------------------------
                                     ANTHONY T. KRONMAN



                                     /s/ Vincent Tese
                                     -------------------------------------------
                                     VINCENT TESE



                                     /s/ Gerald Tsai, Jr.
                                     -------------------------------------------
                                     GERALD TSAI, JR.




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