Ethnographic Arms & Armour - View Single Post - Gentle way to improve Pamor (no chemicals)

A. G. Maisey · 10th March 2022, 08:01 PM

Jean, old fashioned, ie, "old school" blackboard chalk was made from calcium carbonate + some other stuff, but modern chalk appears to be made from gypsum.

http://cameo.mfa.org/wiki/Blackboard_chalk

10th March 2022, 08:01 PM	#13
A. G. Maisey Member Join Date: May 2006 Posts: 6,964	Jean, old fashioned, ie, "old school" blackboard chalk was made from calcium carbonate + some other stuff, but modern chalk appears to be made from gypsum. http://cameo.mfa.org/wiki/Blackboard_chalk