It must be in the steel....
I bought this small bottle probably 10 years ago from Brownell's after having good results with the AGI zinc park. If you keep the parts clean you get an even job. The color results are all over the place however. I did a "rust patina" Remington 1100 with the AGI kit and it turned out gray with just a hint of green after it sat a bit. I ordered this product to do a Colt 1903/8 and an Essex 1911 receiver. The Colt came out greener than the 1100, and the Essex piece was a dark gray. I tried The Manganese based stuff and had a bad experience, so I decided to not use it on this round. The Zinc sat all this time and I pulled it out this wknd to do a RemRand slide that I got at a showa coupla years ago, that a GI armorer had started a post-war NM pistol with. It has the early Bomar adjustable and "whale-tail" sights. The slide grooves were already peened. I finally bought an Auto-ordnance frame and built an erstatz NM gun. It shoots, so I thought I'd try the zinc, and hope for the greenies. Both the frame and the RR slide came out a med gray, but it already is greening a hint. The small parts are a little lighter gray, but it looks ok. They were all GI. At the same time I did an old Essex slide and a mix of modern parts by Smith and Alexander, Wilson, EGW and Spring.. That stuff all came out oxide black. That's good 'cause the frame is black. I prepped it all the same and the parts were mixed at the same time in the solution. So it's gotta be the alloys giving the different colors. I also "aged" the solution by doing a bunch of small parts first, no "iron" filings or steel wool or whatever. I had a bad session with the Manganese solution a coupla years ago, Black dip, aging and all. Very uneven results in coverage. But I did the same prep for everything so It must have been something in the steel wool or black dip. Anyway, I use the small parts to age the solution and it seems to work. So beware if you're mixing old school and "modern" alloys if you want all the same "color". The black dip may help this but I haven't used it in a successful way. So the Zinc seems to be more forgiving than the Manganese in uniform coverage. YMMV of course.
