Almost everyone who has installed or helped to install porcelain or glass mosaic tile has had to correct the age-old problem known as thin-set mortar squeeze-up between each tile. The removal of the mortar is probably the least favorite part of a tile installation and many times reserved for the newest member of the team who has to rake out the excess mortar with a tile spacer, margin trowel, a piece of cardboard, or even a popsicle stick.
To eliminate this problem, many installers use some reasonable logic to solve this dilemma. You would think if squeeze-up is to be eliminated, the use of a smaller trowel would be the best choice. Many times, this trowel of choice is a 5/32” or 3/16” “Vee” notch, but actually, this is a really poor decision. The Vee-notched trowel provides about 8-12% mortar coverage on the back of the tile, but many times these mosaics are installed in wet areas which require a minimum mortar coverage of 95%.