Cracking the Code on Why is My Resin Sticky

why is my resin sticky

You select your resin, mix the two parts together, then use it for your project only to find later that it is sticky. Finding sticky resin is of the worst things ever. I’m going to say it — it’s infuriating. Now you find yourself asking 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’re essential. The best way you can do that is by using mixing cups with graduated lines to measure as precisely as possible. With small mixes, this is even more important! Or, if your resin kit allows it, you can use a digital scale to measure your resin and hardener by weight.

Undermixing resin and hardener.

Mixing ‘eh, good enough’ won’t cut it here. You need to scrape the sides of your cup and stirring stick several times. Make sure you bring that unmixed resin to the center of the cup and continue blending.

Pro tip: Ever have cured resin but with a few sticky spots? You likely mixed the center well, but not the resin on the side of the cup. When you scraped out the cup to use that last bit of undermixed resin, it cured sticky.

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.

Pro tip: Warm up your resin and hardener bottles in a hot water bath before use. This helps the resin curing reaction get to the ideal temperature.

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

In order for two-part resin to cure completely, you must mix together a minimum of Part A resin and Part B hardener. That means you can’t mix together two drops of resin and two drops of hardener and expect the four drops to harden.

Using resin and hardener from two different resin kits.

Resin and hardener are specifically designed to go together. Unfortunately, one kit’s resin won’t work with another kit’s hardener.

Water contamination.

Depending on what else you use (resin colors, found items, etc.) they can add water to your resin mixture.

The 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.

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

Here’s how to fix sticky resin.

Wondering if you will ever create anything with resin that isn’t sticky?

Let me help.  I wrote the ebook, Resin Fundamentals, with beginners in mind. I’ve condensed my fifteen years of experience into a book of ‘what you need to know’ about resin. I want to help you make something you’ll be excited to show off. It’s all the facts and helpful advice I wish someone shared with me when I started!

Unpublished Blog Posts of Resin Obsession, LLC © 2022 Resin Obsession, LLC

Like this post? You may be interested in  9 Things You Can Do With Your Epoxy Mistakes

29 thoughts on “Cracking the Code on Why is My Resin Sticky

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

  2. 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?

  3. 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.

  4. 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?

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

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

  5. 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?

    1. 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.

  6. 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?

  7. 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

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

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

  8. 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.

  9. 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?

    1. 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?

  10. 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?

  11. Hi! I need help with my problem. It was my first time putting dried flowers in my resin. At first it turned out good then I added the final coating. I noticed it did not fully cured. It’s like it got wet at the middle(the other side is hard). I though my sister might accidentally got some drops of water in it. I tried using flowers in my resin again in another project and it was wet at the middle part again. What might be wrong with it? Please help me, I’m really having a lot of trouble about it. Thank you so much!

  12. hi so my question is, when it’s sticky on the sides should re layer it inside the mold? or how since it’s on the side of the mold

  13. I’m having a hard time getting my resin to cure.
    1) it’s typically my clear resin with only glitter in it. This suggests to me that I’m not mixing it as well as my colored resin…
    2) I live in a cold climate at times. I’m wondering if my temps are effecting it? I keep my home 72 during the day and 65 at night. Is the 65 too cold?

    I’ve made probably 20 different projects and have successfully cured like 5 or 6. I’ve really tried different resins, tried mixing better, tried having the fireplace on. The only constant thing is turning my house down to 65 at night. Is that likely my problem?

    Any other suggestions?

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