What can be done to reverse or treat zinc pest?

A. Zinc pest? All zinc corrosion products are white or light gray. You can remove them with some chemical solution (5% sulfuric acid, then rinse well in sodium carbonate ⇦ this on eBay or Amazon] 5% solution; after that rinse again with water). Any methylene chloride or DMF based paint stripper can be used too. Good luck!

A. I believe what the initial questioner is finding is what we in the antique toy business call "metal Fatigue" - the crumbling or cracking of old metal toys. This affects pre-war dinky toys and other toys of that era that are made of ZAMAC (or MAZAC) alloy - this is a zinc tin alloy and if it's been contaminated with lead it will, over the years recrystallize - no cure. Some toys are fine - no contamination - and are worth lots, compared to the distressed ones.

A. To Dave Shelton, this is NOT 'fatigue'. Fatigue of metals is due to stress, whether heat, vibration, or directional forces. Bending and vibration will cause micro-cracking and crystalline structures which have no integrity. They eventually cause massive structural failure.

Zinkpest, or 'zinc pest' as we call it in the English-speaking world, is strictly 'chemical' in nature. It is the natural breakdown of incompatible alloys, and it depends on various impurities and alloying mistakes ... or in some cases, purposeful and money-saving reasons during manufacture. Zinc pest is irreversible, and progressive. Those two factors mean the complete loss of the function and of the value of the item in time.

To John Guy M. Moore,

The zinc pest problem was for the most part resolved after the 1950s with a few exceptions, but there's been a resurgence of it in replicas made since about the mid 1990s. Certain brands are notorious for it now, while other brands are largely unaffected. Ironically, my experience has been that expensive collector quality replicas seem to be affected by it more often than the cheaper more toy-like replicas. There are particular replicas that have a high incidence of zinc pest; I recently bought an expensive tractor replica, only to find that it was affected by zinc pest. Since then, almost every other example I've seen of that same replica is affected too. And I'm losing an expensive very hard to find tractor replica to zinc pest, as well as a few of my smaller diecast cars. At least a couple of my larger diecast cars are deteriorating and others are beginning to look suspect. I'm keeping most of mine, time will tell what rots and what doesn't. Anything that rots is getting tossed. I am however, very reluctant to buy any expensive new releases for fear of losing them to zinc pest. For more expensive items, I now only buy older releases (15+ years old) that have survived. I don't think there's any need to sell your collection, but be prepared for the possibility of seeing zinc pest in a few items. Contrary to what some people believe, the condition is NOT contagious, it can't spread from one model to another.