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## tinting slip--brongniart's formula

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

Linda=3D2C

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

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=
=3D
=3D2C as
will be described below. But first=3D2C let me present the formula=3D2C her=
e ex=3D
pressed
in convenient metric units. The only measurement that you need to make is t=
=3D
o
determine the density of your slop=3D2C by weighing one liter of it=3D2C in=
gra=3D
ms. Then
plug that density value into Brongniart's formula:=3D20

=3D20

grams
of dry matter per liter of slop=3D20

=3D20

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

=3D3D =3D20
____________________________________________________________=3D20

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

=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=
e
formula simplifies to:=3D20

=3D20

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

=3D20

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=
=3D
=3D3D
833.3 g dry matter per liter. And since the total slop mass is 1500 g=3D2C =
we=3D
also
know that the glaze slop contains 1500-833.3 =3D3D 666.7 g water per liter =
of=3D
slop.

Have fun with a little math!

Tig Dupre
in Port Orchard=3D2C WA

=3D

### Edouard Bastarache on wed 8 dec 10

Tig,

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

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

Gis,

Edouard Bastarache
Spertesperantisto

Sorel-Tracy
Quebec

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