Yeah, that sounds right. The seller was a little vague, like it was a deep dark secret, but I looked it up because it sounded familiar, and thought I remembered a discussion in some thread a while back.
Does that stuff actually work? And does removing it with alcohol cause more damage to the rubber?
Ruth Morrisson aka inkstainedruth
In my experience (I don't use it but have seen pens stained with it) it's not convincing. It looks like what it is, a painted layer on the pen. It can be removed with polish or even water, but it leaves residue in chasing or scratches on the surface of the pen which are very hard to remove. Best left alone, in my opinion.