Use of the 1:2 chromium complex of 1-amino-2-(3', 5'-dinitro-2'-hydroxyphenylazo)-4-sulfonaphthalene and alkali metal salts thereof for dyeing polyamides and oxide layers on aluminum and aluminum alloys

Granted: Sep 4, 1984 Filed: Aug 22, 1983

This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.