QUESTIONHow do I install grout on tile murals so it isn't so hard to clean? You recently provided me advice on adhering ceramic tiles to plywood backing boards. Thanks--I used an ANSI A118.11 thinset mortar and it worked well on a small (18"x30") mural.
However, I'm having difficulty with the grouts I've used, and have used both sanded and unsanded grouts. My tile gaps have been too wide, causing the grout to crack, and me having to add another course of grout.
I'm soon to complete a larger mural (see attached photos) that will have irregular width gaps between tiles--some up to 1/2". The mural itself will consist of 3 panels, each 36x36", with some tiles up to 3/4" thick. I intend to follow your advice on using hardieboard on plywood with the A118.11 mortar, but could you provide a recommendation on the grout?
I also have had difficulty in removing grout from carved lines in the tiles, and find that I can't get it off by wiping while unset. I've tried a number of options, but have had most success using a dremel rotary tool with a burnishing wheel. Any advice you could provide here would be much appreciated.
ANSWERANSWER - The recommendations of most grout manufacturers is that use non-sanded grouts for grout joints less than 1/8’ wide, but can use it up to 1/8” wide. Grout joints 1/8” up to ½” wide grout joints require a sanded grout. If the grout joint is wider than ½” then you should use what some manufacturers refer to as Saltillo grout or add like a #30 sand mix to the grout to give it more body and resistance to cracking. You can add grout additives, in lieu of water, to the grout to make them more resistant to cracking.
Cracking could be caused by excessive movement within the tile substrate. Also there are supposed to be movement joints at perimeters and throughout the field to some degree depending the application. Those joints are to be filled with a polyethylene closed cell backer rod and with an ASTM C920 sealant over it per manufacturer’s directions. You might want to consider using the ASTM C920 sealant, which is normally a pure silicone or urethane in lieu of the cementitious grout. Using these types of sealants require that you tape each side of the joints and immediately after applying and tooling the joint you carefully pull the tape. It isn’t as easy to clean up if you get messy with it.
If you do continue with the cementitious grout, you can apply a penetrating sealer over the tile before you grout which will act as a grout release. Although if you are going paint or other coating the surface of the mural then you wouldn’t want to do that since it could interfere with the coating. You don’t want to get the sealer along the edges of the tiles or it will prevent the grout from bonding at those spots. Of if you stick with the grout and don’t use the sealer then you can consider applying a mild acid as you clean those crevices with a still brush. Always experiment with whatever method you use to make sure it works to your satisfaction.