hydrometer for small amounts of glazes

[docweathers]

When testing glazes I mix 500 g or less. All the hydrometers I've seen are tall thin things that require quite a lot of glazes to get them to float. Does anyone know of a hydrometer useful in small amounts of glazes?

[Mark C.]

I covered just this subject here

Hydrometer use with small amounts of Glaze -

 

http://ceramicartsdaily.org/community/topic/2787-hydrometer-use-with-small-amounts-of-glaze/page__p__22067__fromsearch__1entry22067

 

 

Mark

[Round2potter]

To measure the specific gravity of your glaze without any fancy tools is easy!

 

I do this to all my new glaze test recipes to ensure my variables are held constant.

 

1. Weigh your graduated cylinder or beaker, write it down,

 

example, 80 grams

 

2. Fill your graduated cylinder to the 100 ml mark with your VERY WELL MIXED glaze, remember that surface tension is in effect so the highest point (the edge) should be flush with the line.

 

3. Weigh the graduated cylinder.

 

example, 220 grams

 

4. Subtract the original weight of the container from the net weight of the container and glaze; this is the total weight of the glaze and water.

 

example, 220grams minus 80grams equals 140 grams.

 

5. Now is the easy part! if you measured to 100 ml in your graduated cylinder the next calculation is already done for you, the total weight found in step #4 is also the specific gravity, all that needs to be changed is the unit.

 

140 grams is the weight of 100 ml of glaze that is 140 grams/ml (which is equivalent to 140 grams/cm3)

 

Always be sure to keep track of your units! the metric system is superior, and i am an American! The gram is based on the weight of one ml of water, so water has a constant specific gravity of 1 gram/ml (at sea level and room temp ~68 degrees).

 

If you measure less than 100 ml (for example 50 ml) all you need to do is multiply the net weight of the glaze and water (but not the contaainer) by whatever will get you to 100 (in my example of 50, you would multiply by 2). In the event that you use more than 100 ml of glaze, you would divide instead of multiply.

 

-Cheers!

[Round2potter]

oh one more thing!

 

remeber to account for your accuracy. if your graduated cylinder has hash marks to the ml the accuracy is to the 0.0 ml

if your marks go to the tenth of a ml your accuracy is to the 0.00 ml.

 

same goes for your scale, if you use a graduated cylinder and scall that only measures to the gram or ml (no the tenth of hundredth) than you can only accurately calculate specific gravity to the 0.0 g/ml; although your calculator might spit out a few more decimal points, you must round to your level of accuracy.

 

kind of a little over the top for all practical matters, but it is important to keep in mind non the less

 

-cheers!