Why Is My Resin Sticky? 6 Causes and How to Fix Them

You waited a full day, touched your piece, and it's still tacky. Frustrating — but very fixable. Sticky resin almost always comes down to one of six causes, and most pieces can be saved. Start by working out what kind of sticky you have, because the fix is different for each.

First, check what kind of sticky it is

The 6 causes of sticky resin

1. The ratio was off

Epoxy needs an exact amount of hardener to react with the resin. Too much or too little and some of it never cures. Fusion kits are 2:1 or 3:1 by weight — use a digital scale and the chart in How to Mix Epoxy Resin Correctly.

2. You measured by volume instead of weight

This catches many beginners. Resin and hardener weigh different amounts per millilitre, so "2 cups to 1 cup" isn't the same as 2:1 by weight. If your kit says by weight, weigh it.

3. It wasn't mixed long enough

Resin clings to the sides and bottom of the cup. If that unmixed film ends up in your pour, you get soft, wet spots. Stir slowly for 3–5 minutes, scrape constantly, and pour into a second cup for a final minute of mixing.

4. The room was too cold

Cold slows the reaction down a lot. A piece that would be hard in a day at room temperature can stay tacky for much longer on a cold winter night or in an air-conditioned room set very low.

5. Humidity or moisture

Monsoon humidity, wet tools, damp flowers or water in the mould can leave a greasy, cloudy or tacky surface. Dry everything completely and work in a dry room.

6. Too much colour or the wrong additive

Adding large amounts of pigment, paint or ink can upset the cure. Use resin-safe colours in small amounts.

How to fix sticky resin

Slightly tacky surface (hard underneath)

1. Move the piece to a warmer room and give it another 24 hours.
2. If it's still tacky, lightly sand the surface once it's firm, wipe off the dust, and pour a thin fresh coat of correctly measured resin on top.

Soft or wet patches

1. Scrape away the uncured resin with a plastic scraper.
2. Wipe the area with isopropyl alcohol and let it dry.
3. Pour a fresh, well-mixed coat over the whole piece so it cures evenly.

Soft and bendy everywhere, or still liquid

If the ratio was badly wrong, the resin won't fix itself with time. Scrape off as much as you can, clean the surface, and start again with a fresh, correctly weighed batch.

📌 Good to know: Adding more hardener on top of sticky resin won't make it cure — it just adds another uncured layer. Always remove the soft resin first.

How to prevent it next time

• Weigh Part A and Part B on a digital scale
• Mix slowly for 3–5 minutes and use the double-cup method
• Work in a comfortably warm, dry room and keep it warm overnight
• Make sure moulds, tools and inclusions are completely dry
• Keep pigments to a small amount
• Give it the full cure time — about 18–20 hours for Vitro 2:1 and about 24 hours for Flex 3:1 at room temperature

Also dealing with bubbles? See How to Remove Bubbles from Epoxy Resin. For a full list of beginner slip-ups, read Common Resin Mistakes.

Still stuck? We'll help.

Send us a photo on WhatsApp and we'll help you work out what went wrong. Damaged or defective kits are replaced — just share a photo or video.

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FAQs

Will sticky resin eventually harden?

If it's only slightly tacky because the room was cold, moving it somewhere warmer often helps. If the ratio or mixing was wrong, it usually won't harden on its own.

Can I pour new resin over sticky resin?

Only over a surface that is firm. Remove any soft or wet resin first, clean the area, then pour a fresh coat.

Why is my resin sticky only on top?

A tacky top with a hard base usually points to humidity, cold air or a slightly off ratio. Warmth and a thin fresh coat normally fix it.

How long should epoxy resin take to stop being sticky?

At normal room temperature, Vitro 2:1 is typically touch-dry in about 18–20 hours and Flex 3:1 in about 24 hours. Cold rooms take longer.