Ron, a lot of people object to "improving" old used chips by adding ink to the engraving. Differences of opinion. I see no harm if it isn't a very expensive or unusual chip. I guess you shouldn't tamper with a museum quality chip. I once wrote about the subject:

I am often asked how to restore the paint/ink that went into the incised engravings/scrimshaw of "engraved" clay poker chips and ivory chips. I smear "oil paint in solid stick form" onto the entire chip, and then I clean it off the surface of the chip with a fine rag or whatever, leaving the paint in the engravings. What I use cost me some $26.00 5 to 10 years ago -- a box of 12 sticks (I use the "ivory black:" and "raw umber" colors) by Shiva by Delta, called "Artists Paintstik," Delta/Shiva, Whittier California 90601. (You will figure out your own way to do this, but I shaved off some of the end of the stick, then mushed it up with a wooden tongue depressor, then applied it to the chip in this softened form.)...... ...... .... Generally, I don’t bother to do this. For one thing, I don’t have the time or patience.

I have used white soap on colored chips about to be scanned.

I don't know what the chip manufacturer's used. Probably varied and changed over the years.

Robt.