Hi Chestnut3, sounds like you read and researched the way I did. I'm sorry I do not know the brand of adhesive or sealant that our installers used, but I can try to locate our 2018 contract because it may have listed the brand. I made sure they put in writing that they were using only a "non-staining' adhesive and they told me it was the same as they use with marble. They also - like every fabricator/slab yard/installer - told me they had "never had a problem" but the difference was that they at least acknowledged that the staining issue was real (unlike Every.Other.Company who swore that it couldn't happen and it must be 'user error'). I also asked them to apply sealant to the underside where the adhesive would be used - it took more time (drying) and I don't know if that was necessary, but since the adhesive used for granite and other stones (i.e., the stuff that every subcontractor most places send out carries on their truck to use with every job) bleeds with marble and quartzite, I thought the extra step wouldn't hurt, even if it didn't help. We purchased our White Macaubus quartzite slabs from Allied Stone in Dallas, TX, and they (or I supposed one of their subs) did the install. They also have a smaller location in Durant, Oklahoma, and we spoke to both locations. Both locations took the potential problem seriously BEFORE we purchased, advised up front that they only use non-staining adhesive for all light colored stones (usually marble, but they also said it's what they use for quartzite), AND agreed to put it in writing. That sold me. Even though you are likely in a completely different location, maybe a call to them could turn up a brand name. We've had our countertops for 4 full years + a few weeks now - kitchen AND two bathrooms - with no staining problem whatsoever. All thanks to everyone who shared on Houzz (and a few from a fabricator's website I don't recall, but mostly Houzz : ))
Q
