Why does temperature affect resin curing?

Resin curing is an exothermic chemical reaction that speeds up with temperature. Every 10°C increase roughly halves the cure time. Below 15°C, most epoxies cure very slowly or incompletely. Above 30°C, the reaction may be too fast, causing bubbles or uneven cure.

What is exotherm and why is it dangerous?

Exotherm is the heat generated during curing. Large or thick pours generate significant heat that can reach 100°C+ in the centre, potentially cracking the resin, warping moulds, or causing discolouration. Pour in thin layers (10mm max) and allow each layer to gel before adding the next.

Does humidity affect resin curing?

Yes, especially for epoxy. High humidity causes amine blush — a waxy film on the surface. It can also cause cloudiness in clear castings. Work in conditions below 60% humidity for best results.

When can I demould my resin piece?

Demould when the resin is firm but not fully cured (typically 50–70% of full cure time). The piece will continue curing outside the mould. Full mechanical properties develop after complete cure (24–72 hours for most epoxies).

CraftCalcs

Resin Cure Environment Calculator

Calculate optimal curing conditions for resin based on type, temperature and project size.

Resin TypeType of resin affects cure time and max pour depth

Batch Volume

Volume measurement

Ambient Temperature

Temperature in degrees

Ambient Humidity

Ambient room temperature

Project Thickness

Enter the project thickness

How We Calculate This

Cure Time Factors

Temperature: Each degree above 20\u00B0C reduces cure time by ~10%
Thickness: Pours over 10mm cure slower but generate more heat
Volume: Larger volumes have higher exotherm risk
Humidity: High humidity causes surface defects on epoxy

Cure times are estimates. Always test with your specific resin brand and follow manufacturer guidelines.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.