I have finally succeeded in purifying clay that I dug up. I have been using the clay for bullets for my sling. I want to try primitive pottery soon. First question is, what do you use as temper to stop the clay from cracking, shrinking and losing weight? I made a ball with the unpurified clay with about 25% sand (builders or sandpit sand whatever you call it) mixed in. It has dried well with no cracking, little shrinking and very liitle weight loss. Is sand good or is there a better choice?Second I am just wondering if anyone has got ideas, websites or resources that can benefit me for trying primitive pottery. For reference, I am in South Africa and my clay is red. I am still not sure if it is great clay but I will soon find out after more experiments! Many thanks.