BISQUE - Damping
Bisque dampened: if you are decorating hand-made bisque objects made from red clay, dampen them before applying the glaze-base. I always do this but it is not absolutely necessary; it helps eliminate air holes and makes the base run on more cleanly and smoothly. Quickly dip the bisque into clean water, so every part gets covered, take it out and let it sit for a short while before applying the glaze-base. Only dampen handmade objects in red clay, not white or industrially-made ware.
When a piece of bisque has many air holes, dip or brush it with water before applying the glaze-base. This avoids air bubbles, takes off the dust and helps the glaze to run over it evenly. With normal industrial tiles damping is not needed, as the bisque is compact and fine.
Remember that bisque made by different firms can react in different ways, so before starting a large job, always test them. The photo below shows an industrial tile 24 × 24 cm. The bisque had a rough texture, full of small holes. To help eliminate some of them we previously wetted the part that was going to be decorated with a large soft brush and clean water. When covered with the glaze-base this blocked some of the holes and when fired the few that were left gave it an antique texture.