You need to search the forum, you will find a large number of explanatory posts by Sue and David to help you.  I will have a look and then give you the url in the next post.  sorry there are too many.  If you click on the magnifying glass icon for search the forum and then type in ground chalk you will find all the posts that it hs come up in. 

You are looking for Calcium carbonate and there are several suggestions about where you can get it from, depending where you are.

Best of luck.  You will probably need to go to either a craft store, ceramicists suppliers or hardware store.

Charlotte

Last edited by newmodeller (2008-05-02 19:29:46)

Places that sell materials for making pottery should have it very cheap (they tend to call it 'whiting'). Be sure to give them all it's names if they look blank. I've never known a material that is known to people by only one name when it has several.  Ground chalk, calcium carbonate, whiting, ground limestone.

Blackboard chalk is either gypsum (calcium sulfate) or calcium carbonate; grinding up the sticks would probably work for PM.

It's also usually the main ingredient in those antacid tablets (TUMS, etc, in the U.S.).

Other sources are your parakeet's cuttlebone, and the White Cliffs of Dover.

Sue

I'm not sure of your location, but you can purchase in the US at any major paint store, like Sherwin Williams or Monarch where it is known as whiting. Didn't know it could be found at ceramic supply...thanks for the tip!