Green waxy formation on the brass

[GaryL]

I am new here but don't know where to find this answer. I have a lot of old Schrade knives with sheaths. Most have been in boxes and in the sheaths for many years. The brass forms some sort of reaction with the leather and causes a build up of a green wax like substance. What is this stuff? What to do about it beside the obvious of keeping them separate in storage? Should it be cleaned and if so how?

 

[Bob W]

It's called verdigris, and the result of a reaction between the brass and chemicals in the leather sheathes.

Bladforums member Codger has a good discussion here:
http://www.bladeforums.com/forums/showthread.php/364472-Verdigris-The-green-slime-(Codger-ramble)

I store knives and sheaths inside the same box with no consequence, but not with the knife in the sheath; the problem seems to only happen if the brass is in physical contact with the leather.

Most have been in boxes and in the sheaths...

That's probably not how they came from the factory. Some folders were shipped with the knife inside the sheath, but the knives were originally wrapped in wax paper. Fixed blades, in my experience, were never shipped with the knife inserted in the sheath.

 

[Codger_64]

Often the fixed blades were shipped in a paper blade sleeve. And sheaths polybagged. These were often thrown away by first purchasers even if the box was kept.

 

[tongueriver]

I am going to stick my neck out here and say that ALL leather is acid tanned, be it via chemicals from a factory or oak bark or whatever. And that there is no such thing as 'oil-tanned' leather; after leather is tanned to preserve it oil or wax or combinations are applied to soften it and give it desirable qualities. Different residual amounts of acid in the leather, and different strengths of acid would act on metals at different speeds. Now, I am just adding this to stimulate the conversation, because I may be quite wrong. What say?

Slightly related: Brass products are often coated with a type of varnish to keep them bright.