There is a product made for the purpose of stabilizing lifting paint
(ink) on the backglasses of pinball machines that may be of use in your
situation.  Use Google to search on 'pinball resource' and look for
'Cover Your Glass'.

The product is a thin liquid that you pour on the painted side of the
glass.  You have to have the glass perfectly level and the stuff takes
a couple of days to set.  It dries crystal clear, so the unpainted
parts of the glass will look no different once coated.

John M Runge