I would like to share my bad experience. About two months ago I have changed my old leather Valve Guard to a new one, made by Reunion Blues, it was not expensive and looking good. Unfortunately I have not take care about one important thing. The older valve guard was made from three layers - leather-plastic foil and something like a felt. The Reunion Blues valve guard has only two layers without the plastic in the middle. I suppose that someting evaporates from the leather , which leads to fast oxidation of the silver. So this guard seems to be more a silver "damager". I have read somewhere, that some acid tawing chemistry could be a reason...
The silver I have on my trumpet was done professionally by AMATI, when the trumpet was refurbished few years before. No protection laquer was used. It is stable, I have no problems with oxidation at all on other pars of the trumpet. On the picture you can see, how does the silver look around the valves after about two months of carrying the Reunion Blues...
Has anybody encountered similar problem?
Sorry for my English,
Pics are few posts below