NOTICE OF GUARANTEED DELIVERY OFFER FOR OUTSTANDING 10% SENIOR NOTES DUE 2007 IN EXCHANGE FOR 10% SENIOR NOTES DUE 2007 OF BURKE INDUSTRIES, INC. This form or one substantially equivalent to it must be used to exchange the Burke Industries, Inc. 10% Senior Notes Due 2007 (the "Old Notes") if certificates for the Old Notes are not immediately available or if time will not permit the Letter of Transmittal or other required documents to reach the United States Trust Company of New York, N.A. (the "Exchange Agent") prior to 5:00 p.m. New York time on January 23, 1998, at which time the right to exchange the Old Notes terminates. This form must be delivered by hand, mail, telegram or facsimile transmission to the Exchange Agent as follows: MAIL DELIVERY TO: United States Trust Company of New York, EXCHANGE AGENT By Mail: United States Trust Company of New York P.O. Box 844, Cooper Station New York, NY 10276-0841 Attention: Corporate Trust Services By Hand: By Overnight Delivery: United States Trust Company of New York United States Trust Company of New York 111 Broadway, Lower Level 770 Broadway, 13th Floor New York, NY 10006 New York, NY 10003 Attention: Corporate Trust Services Attention: Corporate Trust Services - -------------------------------------------------------------------------------- DELIVERY OF THIS INSTRUMENT TO AN ADDRESS OTHER THAN THOSE SHOWN ABOVE DOES NOT CONSTITUTE VALID DELIVERY. UNDER THE TERMS OF THIS DOCUMENT, THE OLD NOTES, A PROPERLY COMPLETED AND DULY EXECUTED LETTER OF TRANSMITTAL AND OTHER DOCUMENTS REQUIRED BY THE LETTER OF TRANSMITTAL MUST BE DELIVERED TO THE EXCHANGE AGENT WITHIN FOUR BUSINESS DAYS AFTER THE DATE OF DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY. - -------------------------------------------------------------------------------- Ladies and Gentlemen: The undersigned hereby tenders the principal amount of Old Notes indicated below, upon the terms and subject to the conditions contained in the Registration Statement on Form S-4 filed by Burke Industries, Inc., a California corporation, with the Securities and Exchange Commission (the "Registration Statement") and the accompanying Prospectus dated December 5, 1997 included therein (the "Prospectus"), receipt of which is hereby acknowledged: DESCRIPTION OF SECURITIES TENDERED - -------------------------------------------------------------------------------------------- PLEASE FILL IN YOUR NAME(S) EXACTLY AS IT APPEARS ON YOUR NOTE(S) PLEASE FILL IN AND YOUR PRESENT ADDRESS NUMBERS AND AMOUNTS - -------------------------------------------------------------------------------------------- NOTE PRINCIPAL NAME(S): NUMBER(S) AMOUNT -------------------------------------- -------------------------------------- -------------------------------------- -------------------------------------- ADDRESS(ES): -------------------------------------- -------------------------------------- -------------------------------------- -------------------------------------- TOTALS - -------------------------------------------------------------------------------------------- Signatures (all registered holders must sign): Address: - ---------------------------------------- ---------------------------------------- - ---------------------------------------- ---------------------------------------- (Please Type or Print) Area Code and Daytime Telephone Number: ( ) - ----------------------------------------- 2 THE FOLLOWING GUARANTEE MUST BE COMPLETED GUARANTEE The undersigned, a member firm of a registered national securities exchange or a member of the National Association of Securities Dealers, Inc., or a commercial bank or trust company having an office, branch or agency in the United States, hereby guarantees to deliver to the Exchange Agent at the address set forth above, Old Note certificates surrendered for exchange hereby in proper form for transfer, together with a properly completed and duly executed Letter of Transmittal and any other documents required by the Letter of Transmittal, within four (4) business days after the date of delivery of this Notice of Guaranteed Delivery. Dated: , 199 Name of Firm: ----------------------------- Sign Here: -------------------------------- (Authorized Signature) Name: ------------------------------------ (Please type or print) ------------------------------------------ (Area code and Telephone Number) Address: ---------------------------------- ------------------------------------------ ------------------------------------------ (Zip Code) NOTE: DO NOT SEND OLD NOTES WITH THIS NOTICE OF GUARANTEED DELIVERY. OLD NOTES SHOULD BE SENT WITH YOUR LETTER OF TRANSMITTAL. 3