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Make your own Hydrometer

Ahydrometer is used to gauge glaze consistency. It is also used in brewing to test the specific gravity of beer or wine, which gives an indication of the alcohol content. However, for us, the hydrometer will fulfill the purpose of making sure that different batches of the same glaze have the same consistency. If not, glaze thickness, and thus the look of a glaze may vary.

Making your own hydrometer is easy enough. The following technique was revealed to me as a student during undergrad studies.

All you need is a piece of aluminum tubing, about 8" (20 cm) long and 5/8" (1.5 cm) diameter. A piece of hard plastic tubing could also be used. Find a large ball bearing that will close up one end and glue it into place with a water resistant glue. Temporarily seal the other end with a piece of cork and see if the hydrometer floats nicely in a bucket of water. If you are satisfied, take the tube out of the water and either scratch in the surface or using a permanent marker, marks of about 0.4 " (1cm) in equidistant from each other. Number your marks from 1-20 (or however many you make) from top to bottom (the bottom is where your weight is). If the hydrometer doesn't float with about half to two thirds of the tube submerged, you need to add some weight. This can be done as easily as just dropping in a couple of smaller ball bearings or some other sufficiently heavy object until you are happy with the result.

Glazes with a higher density will have a higher reading (the hydrometer will float higher in the liquid) and glazes with a lower density will have a lower reading. If a comparative reading is too high, you need to add water, if it is too low, you need to add more glaze powder. Make sure you stir your glazes properly every time otherwise readings may vary, because some materials tend to settle at the bottom of the bucket.

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