February 18, 2013
PRESTO BLACK® BST4 brush-on liquid from Birchwood® Technologies is an instant-acting cold blackener for all iron and nonstainless steels. When applied to any clean ferrous metal surface, the product blackens within 30 seconds and forms a durable black finish that can be topcoated.
The liquid is suitable for use in the aerospace industry as a blackener for rebuilding pistons, bearings, crankshafts, and remachined areas or other reworked metal parts. It also serves as a manual black oxide process for brush-on requirements. In the machine shop, it blackens remachined areas or reworked metal parts and serves as a quick repair for scratches or damaged areas on parts previously black oxide-finished.