Originally Posted by
walkerwek1958
Stainless steel pitting and corrosion is complex. There’s a phenomena known as crevice corrosion, which occurs when some organic materials are in contact with stainless steel in a stationary environment......which is exactly what you get in the area around a rubber caseback seal when the seal material decomposes in the way 60s rubber gaskets often did. This causes the deep black pitting that’s often observed in the area where the seal has made contact iver a period of many years. I’ve seen this in the chemical industry, it’s often difficult to predict or simulate in testing. I did a fair amount of corrosion trial work over the years involving 316 stainless steel and sometimes the results were surprising.
Stainless steel doesn’t like aqueous chloride solutions and can be affected by stress corrosion cracking, yet I’ve seen plenty if examples where the metal isn’t affected. However, I’ve seen cracked links on old Omega ricegrain bracelets where the fixed links join, but this may be caused by the corrosion products creating mechanical stress and splitting the metal......either way its something I always look for in old bracelets.
Corrosion in the gasket area isn’t usually disastrous, if its in the caseback area a new O ring can usually achieve a seal as it compresses and sometimes a slightly thicker one helps. A light smear of silicone grease ensures the seal area is hydrophobic, which also helps. Corrosion around the glass seal is more of a problem, especially where an acrylic armoured crystal is fitted because the acrylic plastic can’t seal against the irregular surface. One trick I’ve used is to heat the case very carefully after fitting, 70-80degrees is enough, which helps the crystal material mould itself to the rough surface, this can take a vintage watch from zero WR to 1 or 2 bar if it works, but I wouldn’t advise anyone to try it on a built up watch. As a last resort a thin bead of adhesive can be applied but I don’t like doing this.