Brongniart's Formula Calculator
Slip Casting
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Brongniart's Formula Calculator
Calculate dry material content and water content in a slip using Brongniart's formula.
Reviewed by ClayCalc Editorial · Updated
Use 2.6 for mixed clay body slip (default). Pure kaolin: 2.63. Ball clay: 2.58.
Results
Enter your measurements above and click Calculate.
Brongniart's Formula
Alexandre Brongniart, director of the Sèvres porcelain factory in the 19th century, developed a formula for calculating the dry material content of a clay slip from its specific gravity and volume. It remains one of the most useful tools in slip casting and industrial ceramics today.
The Formula
// Slip to dry content:
dry_content_g = V × (ρ_slip − 1000) × ρ_solids / (ρ_solids − 1)
// Where:
V = volume in litres
ρ_slip = slip density (SG × 1000 g/L)
ρ_solids = density of dry clay (≈2.6 g/cm³)
Two Calculation Modes
Slip SG → Dry Content
Measure your slip with a hydrometer and find out how many grams of dry clay are in a given volume. Useful for production consistency checks.
Dry Weight → Predict SG
Start with a known weight of dry material and a target water volume, and predict the resulting slip SG before mixing. Useful for recipe development.
Solids Density Reference
The solids density (ρ_solids) varies slightly between clay materials. Use 2.6 g/cm³ for most mixed clay body slips. Pure kaolin: 2.63. Ball clay: 2.58. Porcelain slip: typically 2.5–2.65. The default of 2.6 is a reliable approximation for most ceramic applications.
Method & review note
About this calculation
Uses weight, volume and ratio relationships. Product data sheets and measured viscosity/thixotropy take priority over generic presets.
Reference: USG — No. 1 Pottery Plaster. See the editorial methodology for testing, precision and corrections.
Input handling: Values are sent to the ClayCalc server for this request and are not written to the application database.