"whit3rd" wrote in message
...
On Sunday, July 14, 2019 at 4:30:15 AM UTC-7, Jim Wilkins wrote:
"whit3rd" wrote in message
...

Other permanent red for walls would be brick, terra-cotta tile,
etc.

A pottery studio owner told me that -all- their red inorganic
pigments
had been confiscated as hazardous. She did still have high
temperature
fire clay and gave me a little.

Probably that's about cadmium red; the duller ochre (Fe2O3) that
gives terra cotta its color, probably is still OK.

Tiles in red are certainly available
https://www.fireclaytile.com/brick/colors/detail/catskill

Red lead (minium) and mercuric (vermilion, cinnabar) pigments aren't
modern, but
are also certainly a hazard.

Another heavy metal, gold, colors glass red (might make a glaze of
bright
red atop a dull tile background).

When I gently brought up the chemistry of pigments it was evident she
didn't know it so I didn't embarrass her with further questions. I
found high temperature ceramic fiber insulation on Amazon instead.
https://www.amazon.com/dp/B077T8HDF3/ref=dp_cerb_1