but for those who were at the Box ON in 2016, this was the material that I donated for the raffle... Bon Echo, didn't you or your girls win a slab?

Yes, thank-you for posting that. I looked at the photos and thought it looked a lot like the San Note stuff we received at Box ON 2016, and was going to confirm that when I returned home.

For those who attended Box ON 2017, the "Big Yellow Taxi" stamp from the Music Through the Decades was carved on that material. My 11-year-old daughter carved it (gouge carving). I can't say too much about how it carved but she didn't seem to have any issues with it. I tried a few test cuts, just to make sure it wasn't too firm or too floppy. Took a heat transfer okay. It is thin but IMO firm enough that it does not have to be mounted - the yellow taxi stamp was unmounted seemed to stamp okay (it's about 2" by 2" size).

But as Bumble said, that material is white with thin blue top layer (so thin in fact that I wonder if it actually is a separate layer or just a staining of one surface). Suspicion is that the white-brown and all-white materials are all the same formula, but who knows.