Pen Potion No.9 "deoxidize" bring black hard rubber back to black

There are a few products on the market that promise to "de-oxidize" hard rubber and bring black hard rubber back to black.  Caution:  Another word for "deoxidize" is "remove". Whether by chlorine chemicals, microbial or enzymatic methods, rubber is removed to get to the underlying yet un-oxidized rubber.  One reason, many pen restorers have shied away from removing surface rubber is because of the loss of the detail in the faint etched patterns or lettering on the pen.  The second reason is that the newly exposed rubber surface will oxidize again unless protected.