RDG Fan,
Not a dumb question. The short answer is "No". The long answer is that it depends on the composition of the zinc melt. Most Zimac formulas have a 50ppm upper spec on lead. You exceed that, and the casting is in trouble. I suspect the higher the concentration of lead, the faster the issue will show itself. The issue is very much on a batch to batch basis. Some batches had lead well below the spec. Those will probably never show the issue. Those that are some modicum over the spec will eventually show the issue. The FM motor trucks you mentioned probably fall into this category. Then there is everything else. A lot of 700Es cast in the 1930s are sway backed. This is a clear indication of zinc pest. You will find very few O gauge American Flyer steam engines for the same reason. Almost all of them have succumbed to this issue. During the late 1930s US manufacturers identified the problem and implemented the cure: Keep the lead out! So most US manufactured cast items since then do not exhibit the problem. The issue cropped up when everyone went overseas, particularly China, and to a lesser extent, Korea. They way their manufacturing infrastructure works, there is no QC, and as long as whatever is in the pot melts, it's good to go. Clearly a recipe for disaster, and one we the consumer are paying dearly for.
Chris
LVHR
