I use this quite a bit doing limestone and marble. Had a failure with it, did the job about 2 years ago onto existing ceramic tiles. Had to go back a few weeks ago to change a few of the porcelain I laid as they had smashed. Took up the tiles and the adhesive just crumbled in my hands, fell off of the back of the tiles and lifted straight off the floor. I sent samples away to BAL to be tested, but haven't heard back yet. If you get no joy with them go to Ceram research. There is an inherant problem in trying to mix white adhesive at the factory, lost count of times I had to throw not only bags but pallets away due to the mix being wrong and the stuff going off as fast as you could mix it.