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I recently bought a new toolbox to tame the piles of tools I've acquired for general home maintenance in my first year of home ownership. It's the Kobalt 26" hammer box; good size, sturdy enough for a homeowner, has a nice detachable parts case, and it wasn't too expensive. It's only problem is that if I take it outside the house it turns me into a big blue walking advertisement for Kobalt tools (I mean, they're not bad, but I'm not exactly shouting their praises to the hills either).

Anyway, one of the things it advertised on its marketing sticker is the "Zerust" brand corrosion inhibitor built into the plastic of the box. On its face, that sounds great; keep your tools in the toolbox and they don't rust. But, it got me thinking; how exactly would something embedded in the plastic inhibit rust on tools stored in it?

Seems to me that a corrosion inhibitor would either reduce the water vapor in the air inside the box, reduce the oxygen in the air in the box, or release something that sticks to the tools and provides a protective layer. Whatever it does, it would probably run out of "capacity" to do these things fairly quickly.


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up vote 3 down vote accepted

The plastic contains Volatile Corrosion Inhibitor (VCI) molecules that are adsorbed onto the metallic surface, protecting the metallic surface by forming a film. The Zerust FAQ claims that the inhibitor “passivate the electron flow between the anodic and cathodic areas on metal surfaces and interrupt the electro-chemical corrosion process.”

Zerust products for storage are advertised as being effective for five years, but I would expect them to be effective for a much shorter time in a toolbox that is frequently opened and used. You may find numbers in the specs for their military products.

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