I generally go with about a 4 to mix-4 parts water-one bleach and find it works fine. How long you leave it in depends on how heavily it is oxidized. I've left them in over night with no problems. Good quality stems will come out the bleach fairly smooth. Others may be pitted lightly.EJames, 50/50 for 30 min.?
The way I understand it,the sulphur in the rubber is what causes the oxidation. The bleach removes that oxidized sulphur on and just below the surface-hence the pitting.I generally start sanding(wet) with 600 grit and work up to 800-1000 then buff.Bleach will not hurt inlaid PLASTIC trademark logos. ANY aluminum( and painted) must be protected with a good coat of vasiline.