SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                  SCHEDULE 14A
                                 (RULE 14A-101)

                            SCHEDULE 14A INFORMATION

PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE SECURITIES EXCHANGE ACT OF 1934

FILED BY THE REGISTRANT  [ ]

FILED BY A PARTY OTHER THAN THE REGISTRANT  [X]

CHECK THE APPROPRIATE BOX:

[ ]   PRELIMINARY PROXY STATEMENT
[ ]   DEFINITIVE PROXY STATEMENT            [ ]  CONFIDENTIAL, FOR USE OF THE
[X]   DEFINITIVE ADDITIONAL MATERIALS            COMMISSION ONLY (AS PERMITTED)
[ ]   SOLICITING MATERIAL PURSUANT TO            BY RULE 14A-6(E)(2)
      RULE 14A-12

                              HERCULES INCORPORATED
--------------------------------------------------------------------------------
                (NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)


                      INTERNATIONAL SPECIALTY PRODUCTS INC.
--------------------------------------------------------------------------------
    (NAME OF PERSON(S) FILING PROXY STATEMENT, IF OTHER THAN THE REGISTRANT)



PAYMENT OF FILING FEE (CHECK THE APPROPRIATE BOX):

[X]  NO FEE REQUIRED.

[ ] FEE COMPUTED ON TABLE BELOW PER EXCHANGE ACT RULES 14A-6(I)(4) AND 0-11.

      (1)   TITLE OF EACH CLASS OF SECURITIES TO WHICH TRANSACTION APPLIES:
            NOT APPLICABLE

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      (2)   AGGREGATE NUMBER OF SECURITIES TO WHICH TRANSACTION APPLIES:  NOT
            APPLICABLE.

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      (3)   PER UNIT PRICE OR OTHER UNDERLYING VALUE OF TRANSACTION
            COMPUTED PURSUANT TO EXCHANGE ACT RULE 0-11 (SET FORTH THE
            AMOUNT ON WHICH THE FILING FEE IS CALCULATED AND STATE HOW
            IT WAS DETERMINED): NOT APPLICABLE.

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      (4)   PROPOSED MAXIMUM AGGREGATE VALUE OF TRANSACTION:  NOT APPLICABLE.

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      (5)   TOTAL FEE PAID:  NOT APPLICABLE.

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[ ]  FEE PAID PREVIOUSLY WITH PRELIMINARY MATERIALS:

[ ]  CHECK BOX IF ANY PART OF THE FEE IS OFFSET AS PROVIDED BY EXCHANGE
     ACT RULE 0-11(A)(2) AND IDENTIFY THE FILING FOR WHICH THE OFFSETTING
     FEE WAS PAID PREVIOUSLY. IDENTIFY THE PREVIOUS FILING BY REGISTRATION
     STATEMENT NUMBER, OR THE FORM OR SCHEDULE AND THE DATE OF ITS FILING.

      (1)       AMOUNT PREVIOUSLY PAID:  NOT APPLICABLE.

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      (2)       FORM, SCHEDULE OR REGISTRATION STATEMENT NO.:  NOT APPLICABLE.

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      (3)       FILING PARTY:  NOT APPLICABLE.

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      (4)       DATE FILED:  NOT APPLICABLE.

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                    GEORGESON SHAREHOLDER COMMUNICATIONS INC.



                                                                  April 28, 2001



Dear Hercules Stockholder:

         We are forwarding proxy materials from International Specialty Products
("ISP") pertaining to the 2001 Annual Meeting of Stockholders of Hercules
Incorporated. Enclosed is ISP's Proxy Statement, dated March 23, 2001, ISP's
April 28 letter to Hercules stockholders, and ISP's BLUE proxy card.

         Please be advised that since the date of ISP's Proxy Statement,
Hercules has postponed the Annual Meeting, originally scheduled to be held on
April 26, changed the time and location of the meeting and established a new
record date. The Annual Meeting is now scheduled to be held on Thursday, May 24,
2001, at 10:00 a.m., local time, at Hercules Incorporated, 500 Hercules Road,
Wilmington, Delaware. Hercules stockholders of record as of April 12, 2001 will
be entitled to vote at the Annual Meeting.

         If you have any questions or need assistance voting your shares, please
call us, toll-free, at (800) 223-2064.

                                   Sincerely,

                                   Georgeson Shareholder Communications Inc.