appreciate less dust. Well-bonded epoxy coatings ––––– To address an epoxy-coated con- crete substrate, tile installers used to face the need for sand blasting or grinding the surface. Epoxy-coated concrete block walls are still found in many schools and older gov- ernment/municipal buildings. Tile contractors are also seeing a lot of epoxy-covered floors in older indus- trial buildings that are being convert- ed into popular lofts and condos. To remove the epoxy coating properly, traditionally tile contractors had to hire a subcontractor to do the sand blasting. The process would gen- erate dust and waste materials to clean up. After the epoxy removal, the substrate often needed repair to smooth the surface. The game- changing primers make the prep process much cleaner and faster for the contractor. The surface must be cleaned, inspected for integrity, primed, allowed to dry and then can be tiled. Gypsum-based underlayments –––– Gypsum based underlayments are very common floor substrates for tile contractors. Preparing gypsum com- ponents required a sealer and then a waterproofing or crack-isolation mem- brane to ensure the surface integrity and ensure long term bonding of thin- set mortars. With the new primers, once again the contractor can just prime, allow the surface to dry and set the tile – a more efficient process. Concrete treated with silicate or acrylic resin curing compounds ––– New concrete floor slabs have always posed a challenge for con- tractors to make sure that any sili- cate or acrylic resin curing com- pounds have been removed to avoid interference with bonding tile. The past methodology was to neutralize the compound by shot TECH TALK –––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Removal of well-bonded epoxy coatings is a difficult and expensive task, often requiring specialized equipment, but no longer necessary with the use of high- performance primers. When priming over highly absorptive surfaces such as porous concrete or gyp- sum underlayments, two coats of primer diluted with water penetrate deeper into the porous substrate surface than one coat. They provide for better bonding of the latex modified thin-set mortar. Check manufacturer literature for dilution ratios. 50 TileLetter | September 2017