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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

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
I want to add something.

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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