Color variation between production batches is one of the most frustrating quality problems in ceramic manufacturing — tiles from Monday look different from tiles fired on Wednesday, even though nothing in the kiln settings changed.
Understanding This Defect
The most common cause is batch-to-batch variation in raw material chemistry, particularly Fe2O3 content in the flux. If your feldspar supplier delivers material with Fe2O3 ranging from 0.15% to 0.30% between batches (common for poorly controlled dry processors), your fired body color will vary correspondingly. The solution is a supplier with documented batch consistency. Request COA data from 10 consecutive batches and calculate the standard deviation of Fe2O3. At Ceramic Minerals, our wet-process production maintains Fe2O3 variation below plus/minus 0.02% between batches — a level of consistency that eliminates raw-material-driven color variation.
Solution & Prevention
Every shipment includes a COA with independent verification..