Eden Prairie, Minnesota: PRESTO BLACK® BST4 brush-on liquid is an instant acting cold blackener for all iron and non-stainless steels. When applied to any clean ferrous metal surface, the BST4 solution blackens within 30 seconds and forms a durable black finish that can be top coated to form an attractive, protective black oxide finish.<br />
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For the Aerospace Industry, PRESTO BLACK BST4 liquid serves as a fast-acting blackener for rebuilding processes on pistons, bearings, crankshafts ...This story is related to the following:Blackening Metal Finishes