Zinc Pest

The zinc die-cast alloy used in most model cars is made from magnesium, zinc, aluminium and copper. When mixed in the correct proportions, the material can remain stable almost indefinitely. This Russian-made Lada model, however, is slowly falling apart.

The phenomenon known as “zinc pest” is a gradual process. Intergranular corrosion alters the crystalline structure of the material and causes it to expand. In the early stages, the first signs appear in the paintwork. Later, entire pieces can break away, as can be seen on this model.

The problem originates in the way the alloy is produced: for various reasons, its components may be mixed in the wrong proportions. One possible reason is a lack of manufacturing experience. Limited availability of the four constituent metals can also be a factor, for example during wartime production.

A similar situation existed in the Soviet Union before the collapse of the political system. At the time, the Russian rouble had very little value, making it difficult to purchase sufficient quantities of all the necessary raw materials on the world market.

Zinc pest cannot be stopped. A model this badly affected is therefore, in effect, beyond saving. Should it nevertheless remain part of a collection? That is a decision each collector must make for themselves. This model is now part of a long-term experiment. Take another look at it in a few years’ time.