Except for the painting-it-on part, it sounds like you may be talking about Penetrol.
I use it about every 3 years. It completely deoxidizes the pop top and anything else you put it on.
I use it more like wax, as I apply it to a rag (I use gloves as it's pretty toxic stuff ... and I use it outdoors), let it sit a few minutes then buff it off thoroughly. Be sure the top is very clean as this will attach whatever is on the figerglass to the top permanently. Again, use gloves. You'll go through a few pairs of them. Only takes about 1/2 hour to do.

Bob Stevens
'87 Syncro Westy

 The product's main purpose was as an additive to
> paints to make the paint spread evenly.  I bought a can at a marine outfitter -
> I think West Marine.  After washing the top, I painted it with this stuff.  It
> was incredible.  The top looked better than after I had done all the work
> several years before.  Somehow, I felt almost like I was cheating.  Well, I'd
> like to cheat again, but can't remember how.  One of those dreaded senior
> moments.  Does anyone know the name of this product?  I've tried unsuccessfully
> to find it in the archives.
>
> Tom LaLanne