SantaFe158 posted:D500 posted:I have a question concerning zinc warping and crumbling - the "zinc pest". Perhaps someone here who actually knows the metallurgy of the matter can respond.
So far as I know it is caused by foreign matter in the metal or die when cast; I have heard lead mentioned more than once as the common culprit. I have also heard the opinion - surely wrong - that zinc "always does this eventually". There are some really old stable zinc castings all over the world in all sorts of places.
My question, though, is actually this: can the "weather" - the environment, the temperature, the humidity, "the basement" - affect this warping and crumbling process? Not actually cause it, but accelerate it or make it worse?
This seems unlikely to me, given the ultimate cause. Anyone here (truly) know?
I did a little reading when this issue was mentioned here recently regarding another model. According to an article I found, the environmental factors such as high humidity can accelerate the process, though any piece suffering it will eventually fail. From what I understand, higher amounts of lead or other impurities (though I think lead is the main one) in the alloy cause the problem. Castings that are 99%+ zinc don't have this issue.
OK - everyday, non-extreme environmental factors apparently can affect this process, and lead does seem to be the most common, but not only, cause of zinc casting failure, per the articles quoted above. I did not know this;
I presumed that the "weather" would not affect die-cast metal, beyond typical corrosion/oxidation, if the metal is prone to that in the first place.
