Glazing

From RISDpedia

Glazing Techniques

Glaze can be applied in various ways. Some glazes must be applied in certain ways and not in others. The following is a description of the most common glazing techniques.

Dipping Dipping is probably the most common glazing technique. As the name suggests, a pot or other ceramic object is dipped into a bucket of glaze. This may require a large amount of glaze, depending on the size of the object. If it is a thin necked vase or bowl that is being glazed, the inside may be done first by pouring the glaze in and out again. Then the form is dipped into the glaze with the opening facing down. The trapped air will prevent any glaze entering the already glazed interior. Hint: three-pronged raku tongs are handy for dipping -- they leave only small pin-sized marks which can be smothed over by rubbing.

Pouring Pouring is a technique which may be used if a work is too large to dip, or if there is just not enough glaze available. The ceramic object is held in one hand and glaze is poured over it as evenly as possible, until the whole surface is covered. With this method, overlapping is inevitable. If this is an issue with the glaze used, edges may be smothed over by rubbing with a finger. Hint: do not rub glazes with unprotected fingers if they contain toxic ingredients like lead, manganese or even copper! (Try rubber gloves.)

Spraying Separate equipment is required for spraying, which is not always available in the studio pottery: a glaze spray gun, a compressor, a mask and a glaze booth. The glaze booth extracts fine glaze mist, which should not be inhaled from the air. This is done with an extractor fan. More sophisticated spray booths have a wall of running water to trap most of the glaze, so it is not just ejected into the atmosphere (important where toxic ingredients are used!). Spraying may sound easy but is not necessarily. Spraying the interior of a vase for example would be difficult, as the spray has little room to maneuver in the small space and is ejected again quickly, possibly spraying into your face. To remedy this, such vessels are first poured and the exterior sprayed afterwards. The advantage to spraying is that glaze cover is very even. This can be crucial with some glazes. Hint: to check the thickness of the sprayed glaze, scratch the surface with a pin. If it is of sufficient thickness, the scratch can be smoothed over by rubbing.

Brush-on Glazes Brush-on glazes are glazes especially formulated for brushing onto ceramic work. This makes decorating very easy. These glazes are formulated so that brush marks will largely smooth over, but at the same time the glaze won't run, if fired to the right temperature. Brushing on glazes also enable variations in decoration, that would otherwise be impossible. The difficulty is getting the combination of thickness and firing temperature right, but this is -- as with so may things -- a matter of trial and error.

Source: Ceramicstoday.com