We have an 80 year old house with 1950's PINK tile on the lower half of the bathroom walls. The shower stall has been tiled with a newer and better quality tile. I understand that if I remove the pink tiles, the wall will be so damaged that we will have to replace it. This ia a bigger job than I'm willing to undertake at the time. How can I paint over these tiles? They appear to be made of plastic rather than ceramic.