SCUM
ca: SALNITRE
es: SALITRE
Scum is efflorescence in clay: When red clay is fired and becomes bisque, sometimes bits of white scum can form in the surface that cannot be seen in the clay. They are very difficult to remove and if removed will leave an indent in the surface of the bisque. If not removed, scum will damage the glaze and leave a round depression when the clay is fired.
