People who have been doing this for a long time don't make a big mess like me, but my fingers and even the bottoms of my shoes get smothered in the stuff every day. Mordor ... mortar; get it?

BTW, the mortar I am using for this project is Custom Building Products Natural Stone and Large Tile 50 lb. White Premium Thinset Mortar. When it dries white, it blends in very well with the Carrara tiles I'm using, so less to worry about if any of it sneaks out and stays visible. It's what's known as a polymer-modified mortar, which is specified for use over RedGard and one of two types of mortar specified for GoBoard.

I am using a lot of thinset. Certainly more than any pro would use, and maybe even more than is healthy. I'll have to check with the Surgeon General on that point. My theory was that using a thick layer of thinset would let me correct lippage by squeezing out the excess with my leveling system. That would probably work if i moved at the speed of an experienced tiler. But at my rate, I have a lot of tile row tops exposed overnight. If the next row of tiles needs to squash down for lippage, it won't really work since the previous row's mortar is already pretty well set up by then.

I think I will have used at least 4 bags of thinset my the time it's done. It's an open question whether it will stretch to a fifth bag. To any professional tile setter, that probably sounds like a heck of a lot for a tub surround, even granting that I'm going all the way up to the ceiling.