I have a 1945 bathroom - it is an old school mud job - small blue tiles imbedded in what looks to be 1.5 inches of mud and cement - We want to change the bathroom to something more in tune with the times, and were thinking of having the old tile re-glazed with a different color. BUT I'm wondering if it is possible and/or advisable to tile over the existing tile. The existing tile is in good shape - very well adhered to the wall. Advice please?