How To Restoration & Repair What is zinc pest?

What is zinc pest?

By Rene Schweitzer | January 21, 2024

How can I fix my toy trains with this condition?

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You may have heard the term “zinc pest,” or maybe “zinc rot” or “zamak pest,” but what is zinc pest? And how does it affect toy trains?

In the earlier days of toy train manufacturing, trains and their parts were diecast with alloy metals, made from zinc, aluminum, magnesium, and copper. It was an inexpensive mix of metals at the time that made a solid yet inexpensive product.

Zinc pest is the deterioration of these metals because of lead impurities. Over time, the material slowly expands, cracks, or buckles, making the material brittle. Eventually it can crumble to bits.

Generally, zinc pest affects toy train locomotives from the 1920s through the 1950s. Because of improvements in metal purity and more controlled manufacturing techniques, items made after the 1960s should not have this problem.

Disassembled Lionel prewar locomotive motor
The wheels of this Lionel No. 252 engine were all affected by zinc pest. Hal Miller photo

Not all items from that time period were affected. It depended on the purity of the metals, the manufacturing process, or even if workers tossed trash into the mix of metals that day (yikes).

How can I stop zinc pest?

Close-up of a bad Lionel wheel with zinc pest
A closeup of one of the wheels shows the damage to the pot metal.

Some hobbyists claim that you can slow the deterioration by soaking the affected parts in vinegar. I have also read that a controlled environment (less humidity) can help, or that you can try using an epoxy glue to hold things together and buy you more time. But generally, once the process has started, there is little that can be done to stop it.

What can I do with my items?

If it’s possible, replace the affected parts with new ones. Items such as wheels are not expensive to replace. Check out the repair Hal Miller did to a prewar Lionel engine that had zinc pest on its wheels:


One thought on “What is zinc pest?

  1. This whole topic just drives me crazy! Manufacturers like Lionel and MTH are charging Customers THOUSANDS OF DOLLARS for their engines and train sets only to have them suffer from zinc rot years later! Are you kidding me?! And on top of this Lionel dumped ALL their old parts inventory. So now you can’t even get replacement parts to repair your beloved engines and/or rail cars. Explain to me why I should continue in this hobby?

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