04-13-2010, 02:08 PM
quote:
Originally posted by Carey
I would put a caveat on the acid etching.
It is not etching.
If you are etching, you have too strong a concentration which many home owners always think more is better. The strongest solution available is about 34% which you then dilute as per instructions and yes wear the protective gear.
Grinding can still leave particulates in the pores and on the surface of the concrete that allows the thin set to not bond properly.
Bleach and Muriatic acid are in the same family.
But again this is much like people saying using hardiboard in the shower as backer board is okay. The damage by not doing it properly may not appear for a few years as dinamight is seeing.
Another issue that can cause improper bonding is thin-set mixed in too thin a mix because it is easier to work with, or too little thin set under the tiles. And conversely, allowing thin set to harden slightly before applying.
Getting the concrete slab a little damp before laying the thinset and tile will increase the bonding between the thinset and the concrete.