National Fireproofing Corporation, also known as NATCO, was founded in 1889, in Pittsburgh, Pennsylvania. They re-branded from National fireproofing corporation, to NATCO in 1933. At their peak, they had 23 factories, including one in Haydenville, Ohio.
NATCO manufactured bricks, hollow tiles, and many other building materials.
They are also known for their NATCO conduits. These were telephone tiles, which held underground cables. NATCO conduits were also used as drainage tiles.
In 1933, NATCO changed their official company name from The National Fireproofing Corporation to The NATCO Corporation. Although NATCO manufactured the same products as The National Fireproofing Corporation, there were subtle changes when the company made the transition. The conduits were always called NATCO Conduits, but before the change they said “Manufactured by The National Fireproofing Corporation” after the change it became “Manufactured by The NATCO Corporation”. Since this change occurred in 1933, this information can be used to roughly date NATCO’s products.