Clay & Shrinkage

Crack Risk Calculator

Assess the cracking risk of a ceramic piece during drying based on form, clay type, and conditions.

Reviewed by ClayCalc Editorial · Updated May 2026

Average Wall Thickness

Thickness Variation

Clay Type

Drying Conditions

Humidity

Has joined sections (handles, coils, slabs) Has sharp inside angles or abrupt transitions

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Results

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Enter your measurements above and click Calculate.

Understanding the Risk Score

The crack risk score (0–15) combines six independent risk factors, each scored based on research and studio practice:

Factor	Low Risk	High Risk
Wall thickness	≤ 6mm	> 25mm
Thickness variation	≤ 10%	> 50%
Drying speed	Slow (covered)	Fast (heat/fan)
Clay type	Earthenware	Porcelain
Joined sections	No	Yes
Humidity	> 50%	< 30%

Scores 0–3 = Low Risk. 4–6 = Moderate. 7–10 = High. 11–15 = Very High. Follow all displayed recommendations to reduce risk.

Method & review note

About this calculation

Uses measured dimensions or weights and a stated arithmetic model. Clay and forming method vary, so production decisions should use test pieces from the actual body and firing.

Reference: Digitalfire — Drying Shrinkage. 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 Clay Shrinkage Test

lightbulb Quick Tips

check_circle The most common cracking point is always the thinnest area. Consistent walls reduce stress dramatically.
check_circle Score and slip joints at leather-hard stage. Both surfaces should be at the same moisture level.
check_circle Porcelain pieces should be dried inside a box or under a dome to maintain high humidity around them.
warning In dry climates (< 30% RH), always cover work — even earthenware dries too fast to be safe.

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Frequently Asked Questions

Why do thick and thin walls crack differently? expand_more

Uneven wall thickness causes differential drying — thin areas dry and shrink before thick areas, creating internal stress that leads to cracking at the transition point.

How can I prevent cracks at joined sections? expand_more

Score and slip joining surfaces thoroughly, ensure both pieces are at the same moisture level (leather hard), and compress the joint well. Wrap the joined area with plastic to slow drying at that point.

Is porcelain harder to dry without cracking? expand_more

Yes. Porcelain has very low plasticity compared to stoneware and is extremely sensitive to uneven drying. It requires slow, even drying — typically covered for 24–72 hours before any exposure to air.