Calculate how large to make your greenware to achieve the desired fired size. Accounts for wet-to-dry and dry-to-fired shrinkage across common clay bodies.
Common Clay Bodies
📏 Two-stage shrinkage: Clay shrinks twice — first as it dries (wet to bone dry, typically 5–8%), then again during firing (dry to fired, another 5–10%). Total shrinkage combines both stages. Some clays list total shrinkage (wet to fired), others list each stage separately — always check which your supplier means.
🧪 Test tiles: Always make shrinkage test tiles with your specific clay batch. Draw a 10cm line on a fresh tile, dry it, measure again, then fire and measure again. Real shrinkage can vary by 1–3% between batches, especially with reclaimed clay or mixed bodies.
🔥 Temperature matters: Firing to a higher cone = more vitrification = more shrinkage. Porcelain fired to cone 10 will shrink more than the same clay fired to cone 6. Over-firing dramatically increases shrinkage and risks warping.