Hello;

I need to replace an existing kitchen backsplash consisting of plastic tiles. These tiles are kindof like upside down square cup saucers - the middle underneath is higher than edges. While the tiles seem to pop off fairly easily they leave a smooth bump of adhesive on the walls. I'd like to replace the existing tiles with real tiles.

The existing walls are lath and plaster and fairly smooth.

So my question is, do I have to remove the old adhesive? Or can I apply something to level out the surface, apply new mastic/thinset/adhesive, and then attach the new tile? (I would use a bullnose or something similar to finish the top edge.)

If I need to remove the adhesive what would you recommend to do the job? A heat gun and scraper? Remove the old plaster and redo that portion of the wall?

Thank you for the assistance....

Sincerely;
Michelle