It seemed fitting to place these products in the substrate section as they are used in an attempt to level out uneven substrates. Commonly they are used on existing concrete slabs that do not conform to the minimum standards noted in ANSI specifications. The existing concrete to receive tile should be flat with no high or low spots exceeding 1/4" in 10'. These products are produced in pre-mixed or liquid form and dry powder requiring the addition of water.
Tile Doctor Tip: Since the amount of water is critical in the use of this product, always follow the Manufacturers instructions for their use.
The techniques for using levelers vary. In small areas, the levelers can be applied by pouring them into place allowing the product to seek its own level. In larger areas, the products should be aided in the leveling by using a metal or wood straightedge.
Here are photos of these processes compliments of Paramount Tile of California. We see the worker pour in the leveler and then use a straightedge to smooth and perfect the finish.
Next, the leveler is allowed to cure.
Finally, the levelers surface is fine tuned by scraping off the high spots prior to the application of thinset and tile.