The press plate solves the problem of warping or curling of the piece when removed from the kiln. Immediately after you take your piece out of the kiln use the plate to press the piece flat. It is recommened the surface underneath is metal or burn resistance. Some cracking may occur so multiple firings may be needed.
This is the large model, so essential for firing larger tiles. The press plate is made from low carbon steel with and aluminum handle. The steel measures 1/2" thick and 12X12 inch square weighing approximately 20 pounds.
 "Large Press Plate")