For Amaco, Laguna and Spectrum glazes (other than Nova's), when you purchase them in liquid form (pints, gallons, etc) they are are formulated for brushing.  When you purchase them in dry form, they are formulated for dipping, pouring or spraying.  Coyote glazes (and Spectrum Nova glazes) are formulated the same whether purchased in liquid or dry form.  

As a general rule of thumb, for 1 lb of dry glaze powder, use 11 ounces of water for dipping glaze, 8 ounces of water for spraying glaze, or 7 ounces of water for brushing glaze.  Or, 25 lbs makes about 3 gallons.  This is only a starting point.  

To use a dry glaze for brushing, a brushing medium, such as CMC or glaze medium may be added.  CMC acts as a binder and allows the glaze to flow smoothly. If you purchase CMC or brushing medium in dry form, it is best to add those to your dry glaze before adding water.  Or the liquid forms of CMC or brushing medium will mix more readily into glazes that are already mixed.  

To mix a dry glaze, first add bentonite to the dry glaze to keep it in suspension and increase the drying time.  (Not all glazes will need this.  It depends on the composition.)  Bentonite is mixed at approximately 2 grams (.0044 pounds) per pound of dry glaze.  

Measure water into a clean plastic bucket.  Mix the measured amount of glaze into the water as best as you can.  Then pour the mixture through a sieve into a second bucket, pushing the clumps through the sieve with a rib or other tool.  Repeat several times.  (Note: Glaze recipes sometimes specify a mesh to use, and that will affect the outcome of the glaze.  Otherwise, for glazes, 80-100 mesh are most common.  (Lower numbers are usually for mixing slips.)

Optionally, a hydrometer could be used to check the viscosity of the mixed glaze.  The hydrometer reading should be approximately 900-1000 for dipping, 1500-1700 for spraying, and 2200-2500 for brushing.  

Let the glaze sit for 24 hours, remix, then use.

Glaze should be stirred often, as contents can settle during use.  If the glaze thickens over time, you can usually just add water.  

Some people find that if they use a power mixer they don't have to sieve their glaze.  The sieving process accomplishes 2 things.  1) Makes sure the glaze is well mixed, and 2) Gets rid of lumps.

Read Spectrums tips on mixing dry glazes
http://spectrumglazes.com/helpfulhints03.htm