Firing spots

Firing spots in porcelain

Firing spots are brown or black color defects clearly visible, dark bullet holes on the outside of the porcelain. Please do not confuse them with the dark brown bleeding iron spots which originate in the raw material.

The typical burn mark is usually caused by minimal impurities in the kiln atmosphere or by falling solids during stacking in the kiln car, which then lead to these burnt-in impurities in the hard firing on the surface of the glaze. Both firing and iron stains are usually definitely not visible before firing. All of them appear only after firing and cannot be removed without leaving residues.

Clearly visible spots (see picture) or a number of more than 2 on the surface are definitely b-grade (secon choice).