Thinset mortar — it’s just sand and cement, so why have so many different varieties from each manufacturer? After all, that’s the way we used to mix it 30-plus years ago: mix our cement to sand/water ratio for our mortar bed, soak our tile in water, sprinkle some water and dry cement on the surface of the mortar bed, create a slurry, and our tile was set. So nowadays, it must be a way for them to package it differently, then let’s add a little polymer in it so we can charge more. When a tile contractor can purchase a bag of thinset mortar for under $10.00 a bag versus $50.00 plus a bag, it’s a no brainer, right? If you have this type of mindset regarding thinset mortars, you need to start rethinking what is actually happening. Thirty-plus years ago, 8”x 8” tile was the norm. Not anymore. The absorption rate of tile was different as non-vitreous tile was commonly used. Meanwhile, today, porcelain tile is very popular, with a water absorption rate of less than 0.5%. Tiles of today may not bond with methods and materials used in the early years, and that’s where the different types of thinset mortars have come into the marketplace.

I had the opportunity to attend a National Tile Contractors Association (NTCA) training event for gauged porcelain tile panels in Salt Lake City, Utah, and we had some great trainers from DalTile, Custom Building Products, Beno J. Gundlach/Monolit and the NTCA (Photo 1). Mark Heinlein, NTCA, was the lead instructor along with Kolby Colledge and Dave Stewart from Custom Building Products; Stanley Jensen from Beno J. Gundlach; Randy Fleming, NTCA and Jerry Joyce, national rep for DalTile Panoramic products. 

Attendees received hands-on training of the proper installation of gauged porcelain tile panels on floors and walls and we were able to use the tools and thinset mortar required for a successful installation (Photos 2-14)

The industry now has specific guidelines for the installation methods for gauged porcelain tile which is ANSI A137.3-2017 and A108.19- 2017 American National Standard Specifications for Gauged Porcelain Tiles and Gauged Porcelain Tile Panels/Slabs.

We used Custom MegaLite, to set the floor and wall panels. Key features that Custom states are:

  • Maximum flexibility to prevent cracks in tile
  • Unsurpassed bond strength
  • Non-slump for floors, sag and slip resistant for walls
  • Lightweight - 30 lbs. covers the same area as 50 lbs. of traditional mortar
  • Exceeds ANSI A118.4TE, A118.15TE and A118.11 standards without the need for additives
  • Not formulated with silica sand

We heard terminology like “thixotropic,” “rheology,” and SSD. Really? What does that mean to tile contractors that just want the tile to stick? It means a lot. It means that there is science and chemistry involved, and that the manufacturers are constantly working to improve the technology behind mortars and to make the tile setters’ installation a success. So, what does thixotropic mean? Well it’s the ability of the thinset mortar to “stick” when stresses are applied, which we understand as non-sag. And rheology? It deals with shear stresses. SSD is Saturated Surface Dry, and what this means is that we need to wet down absorbent substrates for a better bond. You can see Mark Heinlein using a common garden sprayer to apply water to the substrate in Photo 4

Trying to understand thixotropic, rheology, inviscid fluids, Newtonian fluids, memory fluid, and dealing with deformation gradients, I think I’ll let the chemists who make the dry set thinset mortars do their jobs, and I’ll “stick” to using the recommended products for each type of application and follow their installation guidelines. 

I hope now you understand why there are differences with performance and price with these products. Remember also that there are a lot of other factors that go along with the technology. The biggest one of all is the human factor. Preparation of substrates, proper mixing, using the proper gauged trowel, and understanding the application are what give all the science and chemistry the ability to perform.

I highly recommend the NTCA seminars anytime you have the chance to attend one. The training is top-notch and the networking with other professionals is invaluable. A big shout out to our Team 2, with Eduardo Mijares and his dad from Golden Stone, and Ismael Hernandez, from Tilemaster & Home repair. It was a pleasure working with you!