Weil, Gotshal & Manges LLP
                                767 Fifth Avenue
                            New York, New York 10153
                               FAX: (212) 310-8007



                                January 25, 2002







ISP Chemco Inc.
ISP Chemicals Inc.
ISP Minerals Inc.
ISP Technologies Inc.
300 Delaware Avenue
Suite 303
Wilmington, Delaware 19801


Ladies and Gentlemen:

                  We have acted as counsel to ISP Chemco Inc., ISP Chemicals
Inc., ISP Minerals Inc. and ISP Technologies Inc., each a Delaware corporation
(collectively, the "Companies"), in connection with the preparation and filing
with the Securities and Exchange Commission of the Companies' Registration
Statement on Form S-4, Registration No. 333-75574 (as amended, the "Registration
Statement"), under the Securities Act of 1933, as amended, relating to
$100,000,000 aggregate principal amount of the Companies' 10 1/4% Series B
Senior Subordinated Notes due 2011 (the "Notes") and the accompanying guarantees
(the "Guarantees").

                  In so acting, we have examined originals or copies (certified
or otherwise identified to our satisfaction) of the Registration Statement, the
Indenture dated as of June 27, 2001, as amended by Amendment No.1 to Indenture,
dated as of November 13, 2001, between the Companies, the subsidiary guarantors
party thereto (the "Guarantors"), and Wilmington Trust Company, as trustee (the
"Trustee"), pursuant to which the Notes will be issued (as amended, the
"Indenture"), the form of the Notes filed as an exhibit to the Registration
Statement and such corporate records, agreements, documents and other
instruments, and such certificates or comparable documents of public officials
and of officers and representatives of the Companies and the Guarantors, and
have made such inquiries of such officers and representatives, as we have deemed
relevant and necessary as a basis for the opinion hereinafter set forth.

                  In such examination, we have assumed the genuineness of all
signatures, the legal capacity of natural persons, the authenticity of all
documents submitted to us as originals, the conformity to original documents of
all documents submitted to us as certified, conformed or photostatic copies and
the authenticity of the originals of such latter documents. As to all questions
of fact material to this opinion that have not been independently established,
we have relied upon certificates or comparable documents of officers and
representatives of the Companies and the Guarantors.


                  Based on the foregoing, and subject to the qualifications
stated herein, we are of the opinion that:

                  1. The Notes are duly authorized, and, when duly executed on
behalf of the Companies, authenticated by the Trustee and delivered in
accordance with the terms of the Indenture and as contemplated by the
Registration Statement, will constitute legal, valid and binding obligations of
the Companies, enforceable against each of them in accordance with their terms,
subject to applicable bankruptcy, insolvency, fraudulent conveyance,
reorganization, moratorium and similar laws affecting creditors' rights and
remedies generally, and subject, as to enforceability, to general principles of
equity, including principals of commercial reasonableness, good faith and fair
dealing (regardless of whether enforcement is sought in a proceeding at law or
in equity) and except that the waiver contained in Section 4.06 of the Indenture
may be deemed unenforceable.

                  2. The Guarantees to be executed by the Guarantors are duly
authorized by the Guarantors, and, when duly executed on behalf of the
Guarantors and when the Notes are duly authenticated by the Trustee and
delivered in accordance with the terms of the Indenture and as contemplated by
the Registration Statement, will constitute legal, valid and binding obligations
of the Guarantors, enforceable against each of them in accordance with their
terms, subject to applicable bankruptcy, insolvency, fraudulent conveyance,
reorganization, moratorium and similar laws affecting creditors' rights and
remedies generally, and subject, as to enforceability, to general principles of
equity, including principals of commercial reasonableness, good faith and fair
dealing (regardless of whether enforcement is sought in a proceeding at law or
in equity) and except that certain remedial provisions of the Guarantees are or
may be unenforceable in whole or in part under the laws of the State of New
York, but the inclusion of such provisions does not affect the validity of the
Guarantees, and the Guarantees contain adequate provisions for the practical
realization of the rights and benefits afforded thereby, and except that the
waiver contained in Section 4.06 of the Indenture may be deemed unenforceable.

                  We consent to the use of this letter as an exhibit to the
Registration Statement and to any and all references to our firm in the
prospectus which is a part of the Registration Statement.


                                                 Very truly yours,

                                                 /s/ Weil, Gotshal & Manges LLP