the grooves in the tile adhesive. It appears that this liquid water extracts uncured latex or poly- mer from the day-old adhesive. The movement of moisture under vapor pressure, particularly when sunlight warms the tile surface, takes it to the surface of the grout joints, where, on evaporation, the residues are deposited. The same applies for wall tiling applications: grouting soon after installation is important in the pre- vention of water entry. If the wall has an open top, such as a fence or balustrade, it is important to seal the top, possibly with a cap- ping, to prevent water entry. So, while water entry into ungrout- ed tiling may not be the only cause of latex leaching, it is certainly a major contributory factor. Conclusions While latex leaching has occa- sionally been mentioned in pro- fessional tile journals for over 30 years, it’s more plentiful today due to changes that have occurred in tiles, tile installation, and construc- tion. These changes include the combination of larger, denser tiles, increased use of latex/polymer- modified mortars and thin-set adhe- sive, and greater use of membranes and crack-suppression systems under tiles. Under these conditions, the modified cement products take longer to cure, and in some cases, much longer to cure. If ungrouted tiling is flooded, there is a far greater likelihood of latex leaching occurring, so external tiling should be grouted as soon as possible, to prevent wholesale entry of water into any voids under the tiles. This means covering the ungrouted work if there is any chance of rain. No instances of latex leaching were encountered when rapid-setting adhesive had been used, but the tiling should still be protected if rapid-setting products are used. The information supplied by tile adhesive manufacturers is gen- erally remiss when it comes to warning about likely delays to cur- ing and setting times when dense tiles are installed over impervi- ous substrates, and no informa- tion was found warning that latex leaching could occur if ungrouted tiling was flooded. More detailed information needs to be inserted into specification and instructions underlining the importance of protecting unfinished tiling from rain and flooding. If the tiling is inundated the wet vacuuming and adequate drying time must be allowed before grouting to avoid latex leaching. There also appears to be an opportunity for chemical engi- neers to test if some adhesive additives are greater contributors to latex leaching than others. This could allow for the development of superior external tiling adhe- sives that would be less likely to present with latex leaching. TECH TALK ––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 88 TileLetter | 2018