Talc is a material used in clay bodies that helps to prevent moisture absorption. Its presence in low fire white clays especially prevents crazing of the glazes, this is also true to a lesser degree in mid-fire clays, especially porcelains. The Texas talc mines are no longer selling their talc commercially…
DalTile OWNS and OPERATES the Talc mines in Texas [as they have since 2017. Technically, they have owned them for much longer, but there is a very LONG story on which-company-bought-which-one-in-what-year. (C-95, C-98, TDM-95, Pioneer, AmTal.) It is the only remaining, white-burning vein of talc in North America that is being mined. They last sold it to market through the company name Natural Minerals.
in 2020, DalTile’s parent company (MOHAWK) decided to shut down Natural Minerals, and cease selling talc to EVERYONE. Distributors, manufacturers, and the rest of the industry were informed at that time, and given the opportunity to place final orders. The last shipments went out in Q1 of 2021.
The talc mines are still in operation, but DalTile is keeping the talc for its own manufacturing uses.
There are other talc mines in the US (Montana), but their talc fires with a noticeable yellow-ish cast. Currently, you cannot make a white clay or slip out of them. There has been *some* testing in glazes, but we do not have any information regarding suitability for a particular glaze.
YES this is a struggle…for everyone involved.
From the time the announcement was made, we went to work on reformulating all of clay bodies that contain talc. Earthenware white was the biggest struggle because 42% of the clay body was talc.
We believe that our chalk rock clay will work well in most applications where Earthenware White was previously used. We also found that for the BEST glaze fit, increasing your bisque temperature from Cone 04 to Cone 01 was extremely beneficial with minimal increase in time or cost of that firing. In some cases this is not necessary, for instance if you use underglazes and a clear glaze (we found Spectrum 700 to work the best with Mayco clears as a close second) the increased bisque temperature is not necessary. Most Mayco Stroke and coats also seemed to perform well with no crazing observed on 04 bisque.
We are continuing to test this body and relies on customer feedback to make any necessary tweaks for better performance.
Feel free to use our feedback from to share your experiences http://kansasclay.com/feedback/