Blackening brass problem - Metal Work, Soldering and Metal Fittings - Model Ship World™

I've run into a problem blackening some brass parts. I've done it hundreds of times before without a problem. Sand or file the pieces, pickle in vinegar for an hour and rinse. Soak in Acetone for an hour and rinse. Put in 1:5 dilute Blacken-It for an hour. There is a reaction, but the result is a

Black wire for eye bolts/rings - Metal Work, Soldering and Metal Fittings - Model Ship World™

Orion mPulse Pulse Arc Welder — Sunstone Welders

darkening agent for metal parts

Leann Whisenant, Author at Fabricating and Metalworking

Solder and brass blackening - Metal Work, Soldering and Metal Fittings - Model Ship World™

SOLDERING and burnishing SMALL BRASS PARTS for ship models

How To Blacken Brass Parts : Birch-wood Casey Brass Black

Helix Permanent Jewelry Welder™

soldering brass