Hi Everybody! I have purchased 10 pieces of Concave 10-ball bearing, they were marketed as stainless steel (not here in YYE, not in US, not a store specifically for yoyos).
Once I received them, I cleaned 3 pieces using acetone and lubed them as the usual procedure. I put them each in a yoyo, played for a while and stored them. The string was never removed.
However, the outer race of the bearing, where the string loop stays, turned cloudy. It happened to all 3 of them. It is not shiny as before, it turned into a matte-looking steel. It does not bug me, but I think it is worth to think about this for a while. Does this indicate that it is not really stainless steel?
Just to isolate the case, I swapped the bearings with the one that are not cleaned/lubed. I am thinking that it might just be the acetone. I will check back on them next week.