2:1 vs 3:1 Epoxy Resin – Which One Should You Choose? (Complete Guide)

"2:1 or 3:1?" is the most common question resin buyers ask. The numbers look like a small detail, but they tell you what the resin is made for. Pick the right one and your project is easy; pick the wrong one and you may get heat, cracks or bubbles.

What do 2:1 and 3:1 mean?

The ratio tells you how much resin (Part A) to mix with hardener (Part B):

• 2:1: 2 parts resin to 1 part hardener
• 3:1: 3 parts resin to 1 part hardener

Fusion kits are mixed by weight. For example, 200 g of 2:1 resin mixes with 100 g of hardener, and 300 g of 3:1 resin mixes with 100 g of hardener.

2:1 epoxy resin: for coating and small projects

Vitro 2:1 is a coating resin. It spreads and self-levels into a thin, glass-like layer.

• Pour depth: about 3–4 mm per coat
• Pot life: about 30–35 minutes
• Cure time: about 18–20 hours
• Best for: coasters, trays, nameplates, frames, MDF art, wall clocks, top coats, jewellery and keychains

3:1 epoxy resin: for deep pours and casting

Flex 3:1 is a casting resin. It cures with low heat, so you can pour much thicker layers without cracking.

• Pour depth: up to 2 inches per layer
• Pot life: about 40–45 minutes
• Cure time: about 24 hours
• Best for: flower preservation, varmala blocks, deep moulds, paperweights and large projects

Key differences at a glance

• Thickness: 2:1 is for thin coats; 3:1 is for thick pours.
• Heat: 3:1 is made for low heat in deep layers; 2:1 gets too hot if poured deep.
• Working time: 3:1 usually gives a little more time.
• Finish: both cure crystal-clear and glossy.

📌 Good to know: Never mix Part A from one ratio with Part B from another. Each resin and hardener pair is made to work together.

Which one should you choose?

• Making coasters, trays, nameplates or coating a board? Choose 2:1 Vitro.
• Preserving flowers, a varmala or making thick blocks? Choose 3:1 Flex.
• Want to try both? The Starter Bundle has Vitro 300g and Flex 400g.

Not sure how much to buy? Use How Much Resin Do I Need?

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FAQs

Can I use 2:1 resin for deep pours?

It's not recommended. Thick pours of coating resin can overheat, crack or yellow. Use a 3:1 deep pour resin.

Can I use 3:1 resin for coating?

3:1 is made for casting. For thin, self-levelling coats, a 2:1 coating resin gives the best result.

Which is better for beginners?

2:1 is usually easier for first projects like coasters and keychains.