Why Doesn’t Epoxy Resin Cure and Stay Sticky?

You poured your epoxy resin project, several hours or even days have passed, but the surface is still sticky, soft, or rubbery? This is one of the most common problems beginners face. The good news is that in most cases, the issue can be fixed.

Let’s look at the main reasons why this happens and what you can do about it.

How Does Epoxy Resin Cure?

Epoxy resin consists of two components:

• resin,
• hardener.

When mixed in the correct ratio, a chemical reaction begins. As a result, the mixture gradually hardens and turns into a strong solid material.

If something goes wrong, the reaction is disrupted and the resin may:

• remain sticky,
• become soft,
• fail to cure completely,
• stay liquid.

Main Reasons Why Epoxy Resin Does Not Cure

1. Incorrect Mixing Ratio

This is the most common reason.

Every epoxy resin has its own mixing ratio:

• 100:60,
• 100:50,
• 1:1,
• 100:30, etc.

If you add too little or too much hardener, the resin will not cure properly.

Important:

• always read the instructions for your specific resin;
• measure components accurately;
• use digital scales.

Even a small mistake can ruin the result.

2. Poor Mixing

Another very common mistake.

Even if the ratio is correct, poorly mixed resin can leave uncured areas. This may cause:

• sticky spots,
• soft areas,
• streaks,
• uneven curing.

How to Mix Properly:

• mix slowly and carefully;
• stir for at least 3–5 minutes;
• scrape the sides and bottom of the cup thoroughly.

Professional artists often use the “double cup method”:

1. mix the resin in the first cup;
2. pour it into a second clean cup;
3. mix again.

This helps prevent unmixed material from remaining in the container.

3. Low Temperature

Epoxy resin does not like cold environments.

If the room is:

• too cold,
• too humid,
• drafty,

the curing reaction may slow down or stop completely.

Ideal Temperature:

Usually:

• 22°C–25°C (72°F–77°F).

For some resins:

• 25°C–30°C (77°F–86°F).

4. Pouring the Wrong Thickness

Some resins are designed:

• only for thin layers,
• while others are made for deep pours.

If the resin is used incorrectly, it may:

• overheat,
• boil,
• remain soft,
• crack.

Always check:

• the maximum pour thickness,
• the manufacturer’s recommendations.

5. Too Much Pigment or Additives

Beginners often add too much:

• pigment,
• alcohol ink,
• dye,
• glitter.

This can interfere with the chemical reaction.

Important:

Additives should only make up a small percentage of the total mixture.

6. The Resin Has Not Fully Cured Yet

Sometimes the problem is simply impatience.

Many resins:

• become “dry to the touch” after 12–24 hours,
• but reach full hardness only after 3–7 days.

Do not touch or use the изделие too early.

What to Do If the Resin Is Already Sticky

If the Surface Is Slightly Sticky

Sometimes it helps to:

• leave the piece for another 24–48 hours in a warm room.

If There Are Sticky Spots

You can:

1. lightly sand the surface;
2. remove the sticky layer;
3. apply a new thin coat of resin.

If the Resin Is Completely Liquid

Unfortunately, in most cases you will need to:

• remove the uncured resin completely;
• clean the surface;
• pour a new layer again.

How to Avoid This Problem in the Future

Simple Rules:

✔ Use Accurate Digital Scales

Never measure “by eye”.

✔ Always Follow the Mixing Ratio

Adding “a little extra hardener” will not help — it usually makes things worse.

✔ Mix Thoroughly

Do not rush.

✔ Work in a Warm Room

Best temperature:

• 22°C–25°C (72°F–77°F).

✔ Use High-Quality Resin

Cheap or old resin is more likely to cause curing problems.

Conclusion

In most cases, sticky epoxy resin is caused by:

• incorrect ratios,
• poor mixing,
• low temperature.

Almost every beginner makes these mistakes at first, so don’t worry — with experience the process becomes much easier.

The most important things are:

• follow the instructions carefully;
• work accurately;
• do not rush.

Then your resin will cure properly and your projects will turn out beautiful and durable.

At M | Art Studio you will find professional Italian epoxy resin for art, casting, river tables, jewelry making, coating and creative projects. We offer high-quality materials, detailed instructions, fast delivery across Israel and professional support for both beginners and experienced artists.