You buy resin, mix the two parts together, then use it for your project. But, you come back later to find it’s not fully cured, but instead a sticky mess. Now you find yourself asking why is my resin sticky? There eight reasons why this could have happened.
And the good news is that there are things you can do next time you craft with resin to make sure it doesn’t happen again.
Reason 1: 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.
Reason 2: 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:
Reason 3: 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.
Reason 4: 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.
Reason 5: 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.
Reason 6: Water contamination.
Depending on what else you use (resin colors, found items, etc.), they can add water to your resin mixture.
Reason 7: 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.
Reason 8: This is normal for polyester resin castings.
Polyester resin is kinda weird in that the surface exposed to air during curing will stay sticky, even after a full cure. And if you’re thinking about using it, here’s what else you should know about using polyester resin.
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!
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