Green "Crud" on my Slings?

[22SqnRAE]

David, you're absolutely spot on. Thank you. Buggered if I know what happened there. Verdigris was exactly what I was thinking and managed a 't' instead. The power of suggestion, hey? Well, I feel like a right goose now!

Probably a good reminder to check and double check my typing.

On to Jim's point about the verdigris pressuring rivets. It's a really good reminder that constant preventative maintenance is essential to preserve all things mechanical. As noted, cleaning verdigris out of brass sling components prevents mechanical expansion and damage. In a similar manner to rust expanding 9 times it's 'eaten' volume, which causes an enormous pressure on surrounding components and leads to mechanical failure. Hence why concrete spalling occurs when the reinforcement steel rusts below the surface.

With brass, the verdigris is actually a product of slow dissolving of the metal to other constituent compounds. Leave it long enough and you'll easily see the erosion caused by the conversion of base metal to other oxidation compounds.

While the nice 'patina' and verdigris colouration is appealing to some, they are simply oxidation products of the base metal, meaning the base metal is slowly, but surely, being consumed and no longer it's full size and intended strength. A technical reality that some people in the collecting fraternity neither care for nor understand, form my observation.