Smooth-On

EpoxAmite 103 Slow

Laminating epoxy · US · manufacturer-sourced

Check your container: This countdown is for the Laminating epoxy variant. Similar-looking versions may have different times.

How long before you can demold Smooth-On EpoxAmite 103 Slow?

Short answer

Ready to demold: 20 hours to 1 day after application.
Epoxy

Two-part cure ladder

Pot life, set and full cure all run off the mix time

  1. Mix the Laminating epoxy in the exact ratio
  2. Work inside the pot life
  3. Do not load until the stated cure

This product’s stated stages Quoted at 73°F

  • Working time ends55 minutes
  • Demold20 hours to 1 day

Worth noticing: Working time is only 55 minutes; the next stated stage, demold, is 20 hours to 1 day.

Common mistake: Mixing a large batch in a warm room; the pot life is shorter than the sheet suggests.

Epoxy

Bond-strength path

Assembly, handling and full load are different stages

1 · AssembleClean, fit and apply the Laminating epoxy version correctly.
2 · HoldKeep the joint undisturbed through its set or clamp stage.
3 · LoadUse full cure—not surface firmness—before demanding use.

Time the epoxy cure

When did you mix the epoxy?
Conditions that affect drying
Where?
Thickness

Stated times

  • Working time ends55 minutes
  • Ready to demold20 hours to 1 day

From Smooth-On data sheet · checked 2026-10-25. Anything not listed isn’t stated by the manufacturer.

Manufacturer website: smooth-on.com

Conditions & fine print
  • Stated conditions: 73°F (23°C)
  • Pot life and cure time shorten in warm rooms and with bigger batches. Follow the current technical bulletin for mix ratio, mixing and release agents. The chart is a summary.
  • Region US. Formulas can differ between countries; check your container.
  • Working time ends: At 73°F (23°C); pot life by ASTM D-2471.
  • Ready to demold: At 73°F (23°C).
  • Entered from the cited manufacturer documentation. Check the current label for the exact formula and region. Report outdated information
  • Actual results depend on preparation, thickness, ventilation, temperature, humidity, mixing and substrate.

Confirm this is your product

Closely named formulas, colors and regional versions can use different times. Match these details to your container before starting a countdown.

Exact listing
Smooth-On EpoxAmite 103 Slow
Variant
Laminating epoxy
Region
US
Listed use
laminating, fiberglass layup, coating
Timed stages recorded
tooling, demold
Source checked
2026-10-25

Documentation: Technical data sheet · Technical Data Chart (no revision date)

Condition attached to the stated time: At 73°F (23°C); pot life by ASTM D-2471.

About this product

EpoxAmite 103 Slow is a laminating epoxy on Smooth-On's chart with a pot life of 55 minutes among six rows that run from 11 minutes to 62 minutes. The chart also lists a thin-film working time of 180 minutes, far longer than the pot life because a thin film sheds the heat that shortens a deep mix.

Using this specific product

Smooth-On EpoxAmite 103 Slow is listed here as the Laminating epoxy version for laminating, fiberglass layup, and coating. For mixing and curing epoxy, the useful question is not simply whether the surface looks finished—it is whether the exact next-action milestone shown above has been reached.

Before you start

  • Confirm the package says Laminating epoxy; related versions can use different timing.
  • For laminating, fiberglass layup, and coating, pay particular attention to mix ratio, batch size, temperature and pour thickness.
  • At 73°F (23°C); pot life by ASTM D-2471. At 73°F (23°C).

How to check readiness

Check the coolest or thickest part for firmness before sanding, demolding or loading. The technical data chart gives a pot life of 55 minutes. Flex the mold away at one edge and stop if the casting bends, tears or remains tacky.

Avoid this mistake

A larger batch can heat faster while a thin film may cure more slowly.

Keep going

Questions

How long before you can demold this product?

Smooth-On states: The technical data chart gives a pot life of 55 minutes. Conditions: At 73°F (23°C); pot life by ASTM D-2471.. The technical data chart gives a cure time of 20 to 24 hours. Conditions: At 73°F (23°C).. These are the manufacturer’s stated times, not a guarantee.

Why is the thin-film working time of EpoxAmite 103 Slow longer than its pot life?

The chart lists a pot life of 55 minutes (ASTM D-2471 mass test) and a thin-film working time of 180 minutes. A thin film spreads the heat that a mass holds, so it stays workable longer. Cure is 20 to 24 hours at 73°F.

How does EpoxAmite 103 Slow compare with the rest of the EpoxAmite line?

Its cure time is 20 to 24 hours at 73°F. Across the six rows the cure runs from 6 to 8 hours (101 Fast) up to 24 hours (103 Slow, HT and White 102).

How long do I have to work with this product?

Smooth-On states: The technical data chart gives a pot life of 55 minutes. Conditions: At 73°F (23°C); pot life by ASTM D-2471.. These are the manufacturer’s stated times, not a guarantee.

What affects how long this product takes to dry or cure?

Pot life and cure time shorten in warm rooms and with bigger batches. Follow the current technical bulletin for mix ratio, mixing and release agents. The chart is a summary. Follow the product label for your conditions.

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