Being in the floorcovering biz with plenty of tile experience I have to agree with the suggested use of grout or the tile adhesive mortar, known as "thinset."



Both of these products are usually polymer modified, which adds bonding strength & flexibility. This shouldn't be a problem in the rock wall case but both are designed for 1/2 inch thickness or less. Going thicker than that can cause it to crack (stress fractures) but it can be repaired easily.



If you used grout you'd have a variety of colors to choose from but it's a bit more expensive. It's wtill not much money, though. If you use grout, I'd suggest using "sanded" grout as it has sand in it for extra texture and strength.



If you mix either one of these too thin it will weaken it's strength & bonding capabilities. A thin, creamy paste that drips off your finger tips is good versus a watery mix that runs off your finger tips. About the same consistency as maple syrup. Thereabout.



Show off your work here.



Have fun!

HH
-----
Due to political correctness run amuck,

this ol' hillbilly is now referred to as an:

Appalachian American

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