The glaze composition is largely determined by the effects that characterise that glaze. Consequently, some glazes suspend easily in the bucket and others need help. The first rule is to avoid over-watering the glazes as there is no way that a very thin glaze will suspend well. Some glazes with very low clay content can be treated with bentonite and a flocculant to aid suspension. Our preferred flocculant is plaster of paris – it is cheap, most of us have some in the studio and the effect is long-lasting. Alternatives are Epsom salts and calcium chloride. Pre-disperse the flocculant in water and the resulting slurry gradually to the mixing glaze. As a rule of thumb, you might use one or two teaspoons of plaster per bucket of glaze. Adding bentonite(in similar quantities) can also contribute to improved suspension and better-bound glaze surfaces. Add the dry bentonite to water, blitz with a milkshake maker (or mix by hand and stand overnight) and also add gradually to the glaze until the right smooth creamy texture is observed. This sounds complicated but it becomes second nature after a while.
If your glaze has settled into a hard layer with clear water on top, first scoop off (and reserve) most of the clear water. The glaze can then be (manually) redispersed in the remaining water to the desired consistency. Add back as much of the reserved water as needed. Glazes that have settled like this will almost certainly need the bentonite/ plaster treatment to keep them suspended. They should have the consistency of yogurt when they have been allowed to stand for a few days but should be easy to redisperse with hand mixing.