Why is my resin sticky – my resin is sticky – why does that happen?

why is my resin sticky

You carefully select your resin, mix the two parts together, then pour it in your project only to find the next day that it is sticky or gooey. Sticky resin has got to be one of the worst things ever. It’s incredibly frustrating! No one wants to ask themselves ‘why is my resin sticky?’ There are a few reasons why this could have happened.

Resin and hardener measured inaccurately.

Getting accurate measurements on your resin and hardener aren’t optional, they are essential. The best way you can do that is to use mixing cups with graduated lines to make sure your measurements are as precise as possible. With small mixes, this is even more important! Alternatively, if your resin kit allows it, you can use a digital scale to measure your resin and hardener by weight.

Undermixing resin and hardener.

It’s very important to make sure you mix your resin and hardener together deliberately and thoroughly. This means scraping the sides of your cup and mixing utensil several times during the process.

Pro tip: Ever had a situation where your resin cured but you had a few sticky spots on the surface? You likely mixed the center of your cup well, but the cup edges were not mixed completely. When you scraped out the cup to use that last bit of resin, it did not cure well because it was undermixed.

For extra credit, you can watch my video on how to mix epoxy resin:

The resin and hardener didn’t get warm enough.

Your resin working area needs to be in the low 70’s F (low 20’s C) during the entire mixing and curing time of the resin. It’s also helpful to warm up your resin and hardener bottles in a hot water bath before use.  This helps the resin curing reaction to stay at the ideal temperature.

You didn’t mix enough resin and hardener together to allow the chemical reaction to start.

In order for the mixture to cure completely, you must mix together a minimum of the resin component and the hardener component. Put another way, you can’t mix together two drops of resin and two drops of hardener and expect the four drops to completely harden.

Using resin and hardener from two different manufacturers.

Resin and hardener are specifically designed to go together. Unfortunately, one brand’s resin will not likely work with another brand’s hardener.

Water contamination from within the resin.

Depending on what else you used in your resin (colorants, inclusions, etc.) they may have attracted water to your resin mixture. This can also happen when using molds made from alginate.

The resin and hardener mix needs more time to harden.

Double check the cure time for the resin kit you are using. With any luck, you simply need to give your resin more time to cure.

This is normal for polyester resin castings.

The surface exposed to air during curing will stay sticky, even after a full cure, when using polyester resin.

So, what can you do if you are asking yourself why is my resin sticky?

Like this post? You may be interested in  How to polish resin - different ways of polishing resin

Stay tuned for next week’s tips on how to fix sticky resin.

23 Comments

Katharina Nebel

Great information
Can you tell me why my open bangles open up as they get warm and flexible?
I used Art Resin

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Jane Thomas

I’m a newbie and bought UV Resin online – the foreign one. I cured with a lamp and stick. What resin can I buy to brush onto polymer clay beads and also use on acrylic painted rocks?

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Loretta Sturkie

I made a few pieces of resin in 2 molds two nights. I had started this project the night before that. I checked my pieces and one is a tiny bit sticky in the mold but only at the very bottom of the mold. I had mixed a little bit more resin than I needed and filled 3 small cavities with the extra resin. I am hoping I can remove them all tonight and fix that one very small piece. I’m pretty sure it was because of what you said in the video. I’m a newby and have surprised myself that so far all of my pieces have hardened even when I didn’t think some would. That is why I like Resin Obsession. I learn so much.

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Deborah Allen

I have a resin piece that seemed fully cured knock on it hard for over a week. I went to actually mark it for sale and then it was suddenly sticky – do you know why this could have happened? Please?

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Katherine Swift

What else was included with the resin? It sounds like something else may be affecting the resin.

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Sharon

Hi, I have the same problem. My inclusion was coffee beans. It has not cured again since, and that was several weeks ago.

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Stephanie Roshell

I put resin over rocks. My first set I did look like glass but the 2nd batch I did just looks like a good sealer. What could be the problem?

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Katherine Swift

Hmmm Stephanie. That sounds unusual. I think this situation is best suited for a one-on-one consulting call where you and I talk back and forth about what’s going on. A 15 minute consultation call is $20. I do them by video so I can have a chance to see what you are working on. If you are interested, please send a message through the ‘contact us’ page and I can get this going for you.

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Mary Teran

I saw a tutorial where the lady mixed one ounce of resin with half an ounce of hardener and it came out fine is this acceptable?

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Barbara Weltsek

I’m skeptical of weighing resin and hardener as opposed to measuring volume. Some hardeners and epoxies have different weights resulting in a ratio different from 1:1

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Katherine Swift

Yes Barbara, you are absolutely correct! It’s always best to follow the manufacturer instructions for mixing resin, which usually means measuring by volume.

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Katherine Swift

Hi Peggy, I don’t quite understand your question. Resin should not come ‘premixed’ to you in a bottle. Can you tell me more?

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Peggy

Hi KatherineT
Thank you for responding the bottle says UV Resin Hard, just use it straight from the bottle, my first attempts failed miserably. One bracelet had bubbles and the other the flowers rose to the top. Now im trying to find the right sandpaper to softly sand the bumps out, I find it very conflicting as U Tube has many different ways of using the resin to make the bracelets. There does not appear to be videos for hard resin I see a lot where you have to mix too products together to make the bracelet. I found it hard to get the resin in the mould as well not having the right tools.

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Katherine Swift

Hi Peggy, it sounds like you are using UV resin? Do you have to use UV light to cure it?

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Gail Wheeler Berish

The more I read the more confused. In your video on putting a picture between two pieces of packaging tape: after you cut them out you just laid them on your project and poured resin over them? I thought they had to be glued to the project, dried thoroughly and then resin. You didn’t glue yours?

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Katherine Swift

Hi Gail, I don’t glue my papers in place when I’m using the tape method. Rather, I use a toothpick or stir stick to push them into place. Does that help?

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Kyana

Hello and how are you. i have used a mold making kit called amazing rubber mold and for whatever reason all the piece i made in the molds came out sticky but not the resin pieces that i used in other molds using the same batch or resin, the molds are for whatever reason oily at least thats what they kinda feel like. Is there any way i can fix this issue, the manufactures dont seem to have any solutions and the resin i used was made by the vompany too. i bought 3 boxes and it almost seems like a waste of money. Can you help me?

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Katherine Swift

Hi Kyana, I’m afraid I don’t know of a way to fix molds that come out sticky.

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