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tinting slip--brongniart's formula

updated thu 9 dec 10


=3D?iso-8859-1?B?VGlnIER1cHLp?=3D on wed 8 dec 10


Break out your scales and a sharp pencil. Here is a reliable method for de=
termining both dry weight in a slurry=3D2C and the weight of the water in t=

Brongniart's formula enables one to estimate the
amount of dry material in a given volume of "slop=3D2C" that is=3D2C of a
glaze or slip already mixed with water. This formula has a number of uses=
=3D2C as
will be described below. But first=3D2C let me present the formula=3D2C her=
e ex=3D
in convenient metric units. The only measurement that you need to make is t=
determine the density of your slop=3D2C by weighing one liter of it=3D2C in=
ms. Then
plug that density value into Brongniart's formula:=3D20


of dry matter per liter of slop=3D20


of slop - density of water) (density of dry matter)=3D20

=3D3D =3D20

of dry matter - density of water)=3D20


Because the density of dry matter in most non-lead
glazes is about 2500 g/l and the density of water is about 1000 g/l=3D2C th=
formula simplifies to:=3D20


gm dry matter
per liter of slop =3D3D (density of slop - 1000) 5/3


So=3D2C for example=3D2C suppose that a liter of your glaze
slop weighs 1500 g. Then the amount of dry material in it is (1500-1000)5/3=
833.3 g dry matter per liter. And since the total slop mass is 1500 g=3D2C =
know that the glaze slop contains 1500-833.3 =3D3D 666.7 g water per liter =

Have fun with a little math!

Tig Dupre
in Port Orchard=3D2C WA


Edouard Bastarache on wed 8 dec 10


here is rule of thumb,
I use an empty container of drinking water
sold a the grocery store, containing 4 liters
at the shoulders.
A liquid glaze base of 2,000 grams of dry
materials, depending on the amount of clay,
reaches the level of the shoulders.
It is a non-parametric way of doing things
It it is useful to me on certain occasions
when the glaze base has been mixed and
I want to add something.

Also, you can divide the height of the container
in thenths for smaller samples.


Edouard Bastarache