Cleaning a Brass Mold and ...............

[Mal Paso]

I must have been living under a rock. This is the first time I have heard of it. Other than Jon B's thread are there any other thread's that tell the whys and wherefore's of patinaing a mold? Kevin

That was an idea I had to reduce the ability of Lead Alloy to stick to a Brass Mold (Tinning). Not everyone it appears has tinning problems but several of us do. I tried Liver of Sulfur which took a long time and had limited results. Then I stumbled on the vinegar/peroxide bath to prepare for heat treatment. I think it would be best to do it to a new mold. I think what Gear said about "seeds" of tinning get started is true and unless you get every speck of metal it comes back. My cleaning has had limited success. I'll try the Gear method next on one of the 432256s, then the bath, then heat treat to oxidize.

It may be that a commercial patina is the answer. The jeweler / sculpture patina recipes aren't strong enough. Brass isn't used for sculpture because it does not oxidize well or evenly. The commercial "Patinas" that I found so far for brass that produced a strong even color were really paint. I need to stop by the Monterey Sculpture Center and see what they say. I'll put the Birchwood Casey Product btroj mentioned on the shopping list too. They are one of the top metal finish manufacturers, not just guns.

[another gunslinger]

I have been helped by many threads on this fine site, but this one really saved my my sanity (and possibly a $120 mihec mold). I heated the mold halves in a cast iron skillet mold up and used a qtip soaked in sprue plate lube. Tinning vanished instantly!

One thing that has already been said, but I I have missed in my initial reading, is to warm the mold up to temp a couple times with the blocks OPEN. I disassembled the mold and put both in an old cast iron skillet, mold side up to warm a couple times to "tarnish" the brass. When I originally warmed the brand new mold up a couple times to break it in, it was was closed, probably why I got the the tinning in the first time, as the inside of the mold was hardly changed in color. After cleaning and warming again, the mold has has changed to a nice darker orangish color.