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.   

  1. Thoroughly stir the glaze. 
  2. Wet the hydrometer with a slightly damp sponge.
  3. Carefully lower the wet hydrometer into the glaze.
  4. Wait at least 15 seconds for the hydrometer to naturally settle into the glaze. 
  5. Gently tap the side of the bucket 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

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.

Hydrometer from Big Ceramic Shop
How to use a hydrometer

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