Sand Temper and Drying Cracks: The Temper Fraction That Minimises Combined Crack and Strength Losses in Hand-Formed Ware

This paper addresses hand-formed pots that crack while drying when the clay is used untempered, and weaken when too much temper is added. It presents a temper-fraction selection rule that balances drying loss against fired strength loss, derived entirely from stated assumptions and a computation whose code and full output accompany the paper. The sweep covers sand temper fraction by volume from 0 to 0.3. The headline outcome is: best x 0.25; best loss per 1000 usd 117.9; loss untempered usd 372; strength at best mpa 11.4; crack at best 0.077. These figures identify a specific operating point or bound that a workshop can apply directly, and they also show how quickly performance deteriorates away from it. No kiln was built, no ware was fired, and nothing was measured for this study. SIMULATED, NOT MEASURED.