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I have several Life-Like releases and they all appear fine. I wonder if the manufacturer of MTL frames had a bad batch of Zamak. Environment where the loco was stored likely contributed to the problem. Too bad that we still see the Zinc-pest in fairly contemporary items. I would have thought that the problem resolved decades ago.
Zinc pest (from German Zinkpest), also known as zinc rot and zamak rot, is a destructive, intercrystalline corrosion process of zinc alloys containing lead impurities.[1] While impurities of the alloy are the primary cause of the problem, environmental conditions such as high humidity (greater than 65%) may accelerate the process.
A large problem with early zinc die casting materials was zinc pest, owing to impurities in the alloys.[3] Zamak avoided this by the use of 99.99% pure zinc metal, produced by New Jersey Zinc's use of a refluxer as part of the smelting process.
Looking at the photos, if I hadn't been reading about zinc rot for 50 years, I would have thought somebody tried to clean it with acid. Although...you never know. You may be onto something with the "environment" hypothesis. Salt air at the factory? Or high sulfur-dioxide levels plus high humidity in the casting area? And/or in storage or former owner locations? Granted, Wikipedia is not necessarily the best source, but here is that they have to say about zinc pest-Interesting that the Wiki for actual Zamak (as opposed to generic zinc alloys) is: This leads me to the conclusion (assuming the wiki articles are correct) that many manufacturers are knowingly or unknowingly using cheap zinc alloys while they are advertising zamac. Yet another issue that arises, I suspect, when one is not really a manufacturer, but rather an importer for models made by overseas factories, without adequate supervision.
Don't let DCESharkman know...I don't think he can stand another disappointment