That stuff looks interesting, but it says it works for ferrous metals, which would rule out Zamac. Did you use it on something other than steel?
Nelson
Ex-Southern 385 Being Hoisted
Black Oxide is the industrial process and it ain't cheap. Blacken It works, but IS a bit spotty. A couple alternatives.http://www.victornet.com/productpages/toolblack1.html
http://www.precisionbrand.com/ProductsCatalog/PBPCategoryDetails.aspx?Catid=485
I used the first one YEARS ago on steel and it worked very well. Very black. The key is using the whole 3 step chemical process. degreaser/blacken chem/sealer.
The only other product that blackens I know of is Neolube, which is only graphite supended in alcohol, I think. It tends to rub off, and doesn't blacken as thoroughly as factory blackening does, since it's more of a graphite gray. I've tried Blacken-It as well, and it also doesn't blacken thoroughly. The coverage can be spotty, and it's also slightly corrosive, so it's not a good idea to leave white metal parts in too long.
I'd like to know what process manufacturers use to blacken metal in production.
I recently acquired a number of Central Valley T-39 streamliner trucks (HO), which are constructed of zinc alloy (Zamac) die castings, and are unpainted. Since most of these will need to be black in color, I was thinking of chemically blackening the castings. This seemed like a good idea since I would not have to disassemble the trucks, or mask the wheels, before spray painting, and it wouldn't obscure the fine detail. I've read about Blacken-It on another forum. That product requires dipping the items- which wouldn't work well for the trucks. Blacken-It is also reported to produce more of a brown color on castings. Can anyone suggest a better product, or procedure? Thanks- Richard