A hydrometer is a useful tool to help in achieving the proper thickness of glaze and slip by comparing a mass of liquid material to an equal mass of water, which acts as our control. To use, place the hydrometer in the container of glaze or slip where it will float like a buoy, and the meter can be read. The range for dipping or pouring glazes is 0.9 to 1.00. The range for spraying glazes is 1.5 to 1.7. The range for brushing glazes is 2.2-2.5.