FOR IMMEDIATE RELEASE
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                                                        WEDNESDAY, MAY 16, 2001
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                   GABELLI FUNDS ANNOUNCE INTENTION TO SUPPORT
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                     ISP DIRECTOR-NOMINEES TO HERCULES BOARD
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           WAYNE, NJ---International Special Products Inc. (NYSE: ISP) announced
today that a fund group including investor Mario Gabelli intends to vote for
ISP's four Director-nominees at the upcoming Annual Meeting of Hercules
Incorporated (NYSE: HPC) to be held at the Hercules Country Club in Wilmington,
Delaware next Thursday, May 24th.

           In a filing today with the Securities & Exchange Commission, the
Gabelli-led group said, "Based upon current information and analysis, including
the issuer's insensitivity to shareholders' concerns over its poison pill,
GAMCO, in so far as it has voting authority, is likely to vote for the slate of
nominees proposed by International Specialty Products Inc."

           Commenting on the filing, a spokesperson for the ISP
Director-nominees stated, "We are encouraged by the extraordinary support our
nominees are receiving from Hercules stockholders, large and small."

                                    * * * * *

           International Specialty Products is a leading multinational
manufacturer of specialty chemicals and mineral products .

                                    * * * * *

           This press release may contain "forward-looking statements" within
the meaning of the federal securities laws and, as such, concerns matters that
are not historical facts. These statements are subject to risks and
uncertainties that could cause the actual results to differ materially from
those expressed in such statements.