[LETTERHEAD]


                  CERTAINTEED CORPORATION ANNOUNCES EXPIRATION
                      OF HART-SCOTT-RODINO WAITING PERIOD

Valley Forge, PA, May 11, 2000 - CertainTeed Corporation, a wholly owned
subsidiary of Compagnie de Saint-Gobain (Paris, France), today announced that
the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of
1976 has expired as of midnight New York City time on May 10, 2000.  The waiting
period refers to the time during which the U.S. government could request
additional information or documents with respect to the proposed acquisition by
CertainTeed of Brunswick Technologies, Inc. (Nasdaq: BTIC).  The expiration of
the Hart-Scott-Rodino waiting period has satisfied one of the conditions to the
completion of the acquisition.

As previously announced, CertainTeed commenced a tender offer on April 20, 2000
for all of the outstanding shares of BTI at a price of $8.00 per share, in cash.
This price represents a premium of approximately 46% over BTI's closing price on
Friday, April 14, 2000, the last trading day before CertainTeed announced its
acquisition proposal.  Vetrotex CertainTeed Corporation, CertainTeed's fiber
glass reinforcements business, currently owns about 14% of the outstanding
shares of BTI.

Lehman Brothers Inc. is financial advisor to CertainTeed Corporation and
Compagnie de Saint-Gobain and Dealer Manager for the offer and Innisfree M&A
Incorporated is acting as Information Agent for the offer.

CertainTeed Corporation is a leading manufacturer of roofing; vinyl and fiber
cement siding; vinyl windows; vinyl fencing, deck and railing; ventilation
products; piping products; fiber glass insulation; and fiber glass products for
reinforcing plastics and other materials.  The company is headquartered in
Valley Forge, Pennsylvania, and has more than 7,000 employees and 45
manufacturing facilities throughout the United States.


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This release may contain some forward-looking statements.  The Company
undertakes no obligation to publicly update any forward-looking statements,
whether as a result of new information, future events or otherwise.

CONTACTS:

Joele Frank / Josh Silverman
Joele Frank, Wilkinson Brimmer Katcher
212-355-4449  ext. 110/121