The best way to prepare a countertop is to start with 1/2" plywood and
thinset 1/2'' Durrock cementboard on top.  Here is the exact process:

1.  Cut 1/2" plywood board to match outer edge of the face frame for your
cabinets.  Secure to cabinets with screws.
2.  Mix latex modified thinset and spread on plywood with 1/4'' to 3/8''            
     trowel.  
3.  Cut and place cementboard on thinset.  This includes a 1'' piece
overlapping the front edge.
4.  Use 1 1/4'' exterior screws every 8'' to secure board.
5.  Tape all seams using 2'' fiberglass mesh tape.
6.  Determine layout and patterns.
7.  Tile can then be installed using a 1/4'' square notched trowel or larger.  
It is recommended that you use a latex-modified thinset.
8.  Grout after 24 hours.
9.  Seal all grout after 72 hours.
Countertops
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Countertops
2011.  Touchdown Tile is a Minnesota tile company.  All rights reserved.  All pictures of installed tile are Touchdown Tile installations.