Butterbee,
I have tried 2 large art supply stores, hardware, paint and every other type of store here in Idaho and I have been unable to find it anywhere. I did find it in the Dick Blick art supply catalog, but it was more than I was able to pay. They call it powdered marble dust but it is actually calcium carbonate. Here is a link to the page, hope this helps.

http://www.dickblick.com/zz089/26/

Moni

Probably not much help if your not in the UK but Tirantis sell whiting... good price too... until you remember you have to have it delivered... one day im going to move in next to them!

Once again, having no idea where you are limits us as to advice.

What country?

Here are some leads: it is used as an extender in PAINTS, for POTTERY glazes (calling whiting) and to prevent glass from sticking to kiln shelves, in SWIMMING POOLS to correct pH, in WINEMAKING to lower acidity, in PAPERMAKING as a filler/whitener.

Places that deal in these media should have it. Just be sure to refer to it by ALL its names. Clerks tend to know it only by one name.

Sue