BSI Epoxy – Tips & Usage Guide

When used correctly, BSI epoxies create strong, reinforced bonds and can also be used to fill gaps or cracks in model projects. Follow the instructions below for best results.

Mixing Instructions

All BSI epoxies are mixed 50:50 (equal parts resin and hardener).
Any scrap material can be used as a mixing surface. A plastic coffee can lid or yogurt tub lid work especially well. Anything with raised edges help contain the epoxy, and the flexible surface makes it easy to peel off cured leftovers for disposal.
Dispense equal-length beads of resin and hardener, then blend thoroughly using a popsicle stick or scrap tool.

Working Conditions

Mix and apply at room temperature or warmer.
In cold weather, curing will slow down — if it’s too cold, the epoxy may not fully cure.
At temperatures above 90°F (32°C), working time decreases by about 25%.
Protect your work surface from any potential spillage.

Cleaning & Safety

Before curing, clean tools and spills with acetone or rubbing alcohol. If the surface can be damaged by acetone, use isopropyl alcohol
Do not thin epoxy with additives — this weakens cure strength.
CA glue (cyanoacrylate) can be used sparingly to tack parts in place while epoxy cures.
If uncured epoxy contacts your skin: wash promptly with soap and water.
If cured epoxy or CA glue sticks to skin: it can usually be peeled off and will wear away naturally within a day.
Allergic reactions are rare but always minimize skin contact when possible. For any immediate reactions, go to your nearest hospital.

Working Time

“Minute” designations refer to the working time (the time before epoxy starts to set in a mixed mass).
When spread thin, epoxy cures more slowly, giving you extra working time.

Product Summaries

BSI epoxies work best when matched to their intended purpose. Use the breakdown below to find the right epoxy for your build.

5 Minute Epoxy

Available sizes: 4.5 oz | 9 oz | 13 oz

Slightly flexible, not waterproof
Generates heat as it cures
Bonds with polyester resin
Working time: ~5 minutes
Handle after: ~15 minutes
Full cure: ~1 hour

15 Minute Epoxy

Available sizes: 4.5 oz | 9 oz | 13 oz

Best for larger bonding areas
Accepts colour pastes, silica, micro-balloons, and glass fillers (note: fillers reduce working time)
Excellent for fiberglass
Working time: ~15 minutes
Handle after: ~45 minutes
Full cure: ~2 hours

30 Minute Epoxy

Available sizes: 4.5 oz | 9 oz | 13 oz

Ideal for fillets and structural applications
Highest strength
Waterproof and heat resistant
Accepts all fillers (with shorter working time)
Working time: ~30 minutes
Handle after: ~8 hours
Full cure: ~24 hours

Finish-Cure Epoxy

Available sizes: 4.5 oz | 13 oz

Low-odor substitute for polyester resin (great for fiberglass)
Bonds well to foam and wood
Easy to sand
Best flow at 85°F / 30°C (warm gently with a heat gun or microwave for 10 seconds with the cap off)
Handle after: ~20 minutes
Full cure: ~8 hours