Getting the ratio right is the single most important step in any resin project. Too much or too little hardener and the resin will stay soft, sticky, or tacky no matter how long you wait. This guide covers the correct ratio for every Craft Resin product and the two ways you can measure it.
Ratio by product
| Product | Mixing ratio | Working time | Hard cure | Full mechanical strength |
|---|---|---|---|---|
| Arts & Crafts | 1 : 1 by volume (Resin : Hardener) | ~35 min at 25°C | 24 h | ~21 days |
| Table Top | 1 : 1 by volume (Resin : Hardener) | ~25 min at 25°C | 36–48 h | ~21 days |
| Deep Pour | 2 : 1 by volume (Resin : Hardener) | ~60 min at 25°C | 48–72 h | ~21 days |
| UV Resin | No mixing required — single component | Unlimited until exposed to UV light | 60–120 s per face under a UV lamp | — |
| Silicone (mould making) | 1 : 1 by weight | 20–40 min | 3–5 h at 25°C | — |
"Hard cure" is the point where the surface feels dry to the touch. Full mechanical strength develops over about 21 days — wait longer before putting a piece under load or heavy handling. Demoulding has its own timing: Arts & Crafts 24 h, Table Top 36 h, Deep Pour 48 h. Larger batches give you less working time, not more.
Measuring by volume (recommended, most accurate for beginners)
Use the marked lines on graduated mixing cups, or any two identical measuring cups. Fill each container to the same line — for Arts & Crafts and Table Top that means equal parts resin and hardener; for Deep Pour it means two parts resin to one part hardener. Measuring by volume with matched cups is the method the ratio is designed around, and it's the most forgiving for new users.
Measuring by weight (if you use a kitchen or jewellery scale)
Because resin and hardener have slightly different densities, the weight ratio is not identical to the volume ratio. If you prefer scales:
- Silicone (mould making): 1 : 1 by weight — silicone is specified by weight.
- UV Resin: single component — nothing to measure.
- Arts & Crafts, Table Top, Deep Pour: these products are specified by volume (1:1 for Arts & Crafts and Table Top, 2:1 for Deep Pour); if you'd like the equivalent by-weight figure for your specific kit, our support team can confirm it — reply to any conversation and we'll get you the right number.
Why the ratio matters
Epoxy resin cures through a chemical reaction between resin and hardener, not by air-drying like paint. If the ratio is off in either direction, the reaction can't complete properly, and you'll end up with resin that stays soft, bendy, or sticky even after the normal cure time has passed. There's no way to "add more hardener later" to fix an already-mixed batch — if the ratio was wrong, the best option is usually to remove the piece and start again with fresh, correctly measured resin.
Step-by-step
- Warm the bottles first if your workspace is below 15°C — warm the resin (Part A) to around 30°C in a bowl of warm (not hot) water with the lids sealed. Warm resin measures and mixes more accurately.
- Measure both parts to the same line or scale reading, using identical containers for resin and hardener.
- Mix slowly and thoroughly for at least 3–5 minutes, scraping the bottom and sides of your mixing cup as you go. Under-mixing is one of the most common causes of soft or sticky spots — see our Sticky or Soft Result article for troubleshooting.
- Pour into a clean container without scraping the sides of the mixing cup, since any unmixed resin clinging to the sides can end up in your project.
Related articles
- Sticky or Soft Result — Troubleshooting Incomplete Cure
- Bubbles — Why They Appear and How to Remove Them
- Arts & Crafts vs Table Top vs Deep Pour vs UV — Which Resin Do I Need?
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