WEST SYSTEM

105 Epoxy Resin / 205 Fast Hardener

5:1 mix · US · not yet reviewed

Check your container: This countdown is for the 5:1 mix variant. Similar-looking versions may have different times.

How long does WEST SYSTEM 105 Epoxy Resin / 205 Fast Hardener take to dry?

Short answer

Set / hardened: 6–8 hours after application.
Working time ends: 1 hour to 1 hour 10 minutes after application.
Used for structural applications, load-bearing bonds: elapsed time alone can’t confirm it’s ready. Inspect or test before loading.
Epoxy

Bond-strength path

Assembly, handling and full load are different stages

1 · AssembleClean, fit and apply the 5:1 mix version correctly.
2 · HoldKeep the joint undisturbed through its set or clamp stage.
3 · LoadUse full cure—not surface firmness—before demanding use.

Calculate bond readiness

When was the bond assembled?
Conditions that affect drying
Where?
Thickness

Stated times

  • Working time ends1 hour to 1 hour 10 minutes
  • Set / hardened6–8 hours
  • Can take load or strain1–4 days

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

Manufacturer website: westsystem.com

Conditions & fine print
  • Stated conditions: Pot life stated at 72°F (100 g mass)
  • Pot life is only 9–12 minutes for 100 g mixed in a cup at 72°F. Epoxy cures faster when warmer and thicker, slower when cooler and thinner. Minimum recommended temperature 40°F.
  • Temperature range: 40°F to —°F
  • Region US. Formulas can differ between countries; check your container.
  • Working time ends: Thin film
  • Set / hardened: Thin film
  • Entered from the manufacturer source; second review pending. Report outdated information
  • Actual results depend on preparation, thickness, ventilation, temperature, humidity, mixing and substrate.

Using this specific product

WEST SYSTEM 105 Epoxy Resin / 205 Fast Hardener is listed here as the 5:1 mix version for boat, marine, and wood. 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 5:1 mix; related versions can use different timing.
  • For boat, marine, and wood, pay particular attention to mix ratio, batch size, temperature and pour thickness.
  • Thin film.

How to check readiness

Check the coolest or thickest part for firmness before sanding, demolding or loading. Working time, thin film: 60 to 70 minutes. Cure to a solid, thin film: 6 to 8 hours. Cure to working strength: 1 to 4 days.

Avoid this mistake

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

Questions

How long does this product take to dry?

WEST SYSTEM states: Cure to a solid, thin film: 6 to 8 hours. Conditions: Thin film. Working time, thin film: 60 to 70 minutes. Conditions: Thin film. Cure to working strength: 1 to 4 days. These are the manufacturer’s stated times, not a guarantee.

How long until I can use this product or put furniture or weight on it?

WEST SYSTEM states: Cure to working strength: 1 to 4 days. These are the manufacturer’s stated times, not a guarantee.

How long until this product is safe to touch or handle?

WEST SYSTEM states: Cure to a solid, thin film: 6 to 8 hours. Conditions: Thin film. These are the manufacturer’s stated times, not a guarantee.

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

Pot life is only 9–12 minutes for 100 g mixed in a cup at 72°F. Epoxy cures faster when warmer and thicker, slower when cooler and thinner. Minimum recommended temperature 40°F. Application temperature: 40°F to —°F. Follow the product label for your conditions.

Similar products

All epoxies