Using a hyrdometer

How to use a hydrometer

A hydrometer is a tool used to measure the specific gravity of a glaze, which will tell you how thick the glaze is.

– Thoroughly stir the glaze
– Put exactly 1,000 milliliters of the glaze into the beaker labeled “Hydrometer Testing”
– Wet the hydrometer
– Carefully lower the wet hydrometer into the beaker with the glaze in it
– Wait at least 15 seconds for the hydrometer to naturally settle into the glaze
– Gently tap the side of the beaker a few times to make sure hydrometer completely settles

REMEMBER:  Glazes will have different hydrometer readings.  Here is the list of approximate measurements that our glazes should read on our hydrometer:

Liz Kraus Shino 50
Rutile Blue 50
Rutile Green 49.5
Steve’s Copper Red 52
Temple’s Persimmon 46
Jeff’s Long Beach Blue 53
IUS Celadon 48
Monica’s Seafoam 49
Iron Saturate 48
Missouri Straw 32
Mackenzie White 50
Steven Hill Clear 49
Cushing Satin Black 52.5
Horsley’s Satin Matte White 50

– When testing, if the number on the hydrometer is higher than listed above, add a little water and repeat the testing process until the hydrometer reads the correct number.

If the number is lower than listed above, make a note on the bucket to have someone screen some water off the top of the liquid amount.  (This of course has to be done AFTER the glaze has settled – usually after a day or so has gone by without anyone stirring the glaze)  After screening some water off, then repeat the testing process until the hydrometer reads the proper number.

Here’s a Ceramics Arts Daily article on how to make your own hydrometer: