Sometimes it's a good idea to pull tiles out of different boxes as you work so any slight discrepancy is integrated into the overall look of the job. Spreading the adhesive. If you are installing tile in an area that is going to be exposed to water conditions, use a mastic that is water-proof so that it will hold up well. This is very important. If you are applying floor tile in areas not exposed to water you can use a mastic that is not water-proof.
Epoxy adhesives are also available but their drying times can be difficult to control.
They are more appropriate in areas where high impact strength and chemical resistance are required like for a darkroom perhaps. Before you apply the adhesive, carefully read the manufacturer's instructions for drying time so you don't spread any more than you can work with before it sets up. Usually you want to spread enough mortar for 30-40 minutes work. Spread the adhesive on the floor or countertop using the flat side of the applicator. Once you've applied adhesive on a wide area, flip the trowel around to the notched side, run it at a 45 degree angle to create wide grooves.