How to attach new tiles over existing

Scrub the wall tiles with diluted degreasing cleaner and a nylon scrub brush. Then rinse the tiles with a water-dampened sponge. Put on a dust mask and sand the tiles with a handheld power sander and medium-grit sandpaper to roughen the surface. Remove the sanding dust with a damp sponge. Apply painter’s tape around the perimeter of the tiles to protect the surrounding area from excess tile adhesive. Put on a pair of chemical-resistant work gloves, a dust mask and safety glasses. Mix EPOXY tile adhesive components in a bucket using the precise ratio of materials recommended by the adhesive manufacturer. Deviating from the product’s mixing instructions can cause the adhesive’s bond to fail. Scoop up epoxy adhesive on the flat edge of a trowel and spread the material over the tiles. Epoxy adhesive sets quickly, so work fast or it may dry before you can install the tile. Go over using the notched edge of the trowel. The notched edge leaves ridges of a uniform height through the adhesive. Press the tiles against the wet epoxy. Tap the face of each tile gently with a rubber mallet to seat them into the adhesive. Let the tilesl dry for at least one hour.

For a 3D effect, have you considered staggering them?

That's what I'm doing! Just wanted best method for attaching new tiles over the existing ones. They are scattered among solid white tiles in the area over the cook top and counters. Any suggestion on material I should use to insure a permanet adhesion?

thanks!