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		Forming Techniques for the Self-Reliant Potter (GTZ, 1991, 194 p.)
			(introduction...)
			Acknowledgements
			1. Introduction and scope
			2. Products and options
			3. Main product lines and forming options
			4. Plastic clay forming
			5. Semidry foaming
			6. Mouldmaking and Plaster of Paris
			7. Slip casting
			8. Finishing and quality control
			9. Drying of ware and moulds
			10. Work flow and factory layout
			Glossary
			Tables of weights and measures
			Table of sieve mesh sizes
			Density
			Twaddell scale
			Dry content of liquid
			Pint weights
			Bibliography

Dry content of liquid

MAJ. BROGNIART’S FORMULA FOR DRY CONTENT OF LIQUID

If we know the specific gravity of the material in a liquid suspension and the density of the suspension we can calculate the dry weight of this material from:

Dry weight= (1q-1000) x S/S-1

W = dry weight of material in 1 liter of liquid
lq = weight in grams of 1 lifer liquid
S = specific gravity of dry material

Most clays have a specific gravity of 2.5.

Example: This formula is very useful. Let us suppose we have an already-prepared clay slip and we want to add 5 % iron oxide based on dry clay content. First we measure exactly 1 lifer slip and we find it weighs 1.7 kg. Now we calculate dry content of 1 liter slip using Brogniart’s formula:

Dry weight = (1700-1000) x 25 /(2.5-1)= 1,166 grams

We have, say, 30 lifers slip so dry clay content in 30 lifers is:

30 x 1.166 kg = 35 kg. Addition of 5% iron oxide to dry clay content = 1.75 kg.