Testing

Water Absorption Calculator

Measure fired ceramic water absorption (porosity) using the standard dry/wet weight test.

Reviewed by ClayCalc Editorial · Updated

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Weigh the fired test piece bone dry before soaking.

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Weigh after boiling 2hr + soaking 24hr. Pat dry surface before weighing.

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Results

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Enter your measurements above and click Calculate.

Water Absorption Arithmetic

Water absorption compares a fired specimen's dry mass with its mass after a defined saturation procedure. The calculation indicates accessible open porosity under that procedure. For a result to be represented as ASTM C373 or ISO 10545-3, follow the current applicable standard in full; this page performs only the weight arithmetic.

Absorption % = ((wet_weight − dry_weight) / dry_weight) × 100

Descriptive Comparison Bands

AbsorptionClassificationExamples
< 0.5%Very lowCompare with the product/body specification
0.5–3%LowUseful for a firing-temperature series
3–6%ModerateInvestigate against intended use
6–15%HighRelatively open pore structure
> 15%Very highCheck preparation, firing and test procedure

These bands are editorial descriptors, not ceramic product classes. Absorption by itself does not certify food-contact safety, glaze durability, mechanical strength or freeze-thaw resistance.

Method & review note

About this calculation

Calculates a result from measured specimens. This is a studio aid, not a claim that a certified laboratory standard has been followed.

Reference: ASTM C373 — Scope and Significance. 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.

Read the Water Absorption Test

Frequently Asked Questions

How is water absorption calculated? expand_more
After a documented drying and saturation procedure, absorption is (saturated mass − dry mass) ÷ dry mass × 100. Keep specimen preparation and weighing timing consistent.
Does low absorption establish food safety? expand_more
No. Absorption measures accessible open porosity under the chosen procedure. Food-contact suitability depends on the complete body/glaze system, firing, surface condition and appropriate finished-ware testing.
How should I interpret a result? expand_more
Compare replicate specimens, the clay manufacturer’s specification and a firing-temperature series. A single percentage does not by itself certify product suitability.