ANSWER There are no industry standards for the resin/resin-mesh backing on stones. The best way to learn what the resin is composed of and what its temperature rating is, is to get the information on it from the manufacturer or stone quarry that put it on the stone, or a lab can examine it. I personally do not have information on the tempera- ture ratings of various resins used on stone backing. You can reference the NTCA’s Mesh Backed Stone and Tile White Paper (see the Stone section in this issue, page 78 for the paper), which discusses the other issues you described. This information should help give you a better understanding of the application of resin-backed stones in various installations. It sounds like you will be con- sidering a tear-out and rebuild to ensure that you achieve the proper bond and meet the temperature range of this particular fireplace. I suggest contacting the stone manu- facturer/quarry to determine the type of resin, or if that isn’t pos- sible, replace it with a stone that is not resin/resin-mesh backed. I also suggest contacting the manu- facturer of the setting materials (i.e. thinset mortar or epoxy and grout) that you will plan to use to set the stone. Many product Technical Data Sheets include this informa- tion and can be found on their manufacturer’s websites, or a call to their technical service depart- ment will help you determine the correct setting materials to with- stand the temperature ranges for this product. – Mark Heinlein - CTI #1112, NTCA Training Director and Technical Trainer / Presenter ASK THE EXPERTS –––––––––––––––––––––––––––––––––––––––––––––––––––– 26 TileLetter | December 2017