How To Avoid The 5 Biggest Resin Casting Problems

5 biggest resin casting problems

It was the best of times. It was the worst of times. No, I’m not talking about this famous novel. I’m talking about my first six months as a resin artist. It was back before the days of googling terms like best epoxy resin and having the answer in a couple of seconds. When I started with epoxy seventeen years ago, I only had one book to refer to. And the book didn’t cover everything. And it sure didn’t cover problems you might have with resin casting.

As if the frustration of resin casting problems wasn’t bad enough, I didn’t know why I was making resin mistakes. Much less what I could do to avoid them.

But the cool thing is that I got better with resin. I sold my resin jewelry at shops across the U.S., Canada, and the Caribbean. Fast forward to today, and I’ve helped lots of artists worldwide get better with resin.

I want to help you too.

Here are the five biggest resin casting problems you need to know about.

Plus, the ways you can avoid them so you can fast-track your way to resin superstar status.

cat hair in resin

1. Dust settling on wet resin.

Murphy’s Law applies to resin too. If you’re lucky enough to have a dedicated room for your resin, keep everyone and everything out if possible. Sweep, mop, and vacuum regularly to keep dust to a minimum.

Even after all that cleaning, you need to put a container over projects while they’re curing. And make sure the container is clean too.

⭐️ BONUS: How long does it take resin to dry?

2.  Resin not curing.

Any little bit of extra moisture can turn your resin into a goopy mess of casting problems.

And where does this extra moisture come from?

Anything you add to the epoxy.

If you’re adding colors, you’ll get the best results with colors for epoxy. They’re designed to color resin without causing problems. Acrylic paints and food coloring can make resin bendy. Or can keep it from curing at all.

If you want to embed items in resin, they need to be completely dry. While putting a cheeseburger in resin might seem like a funny gag gift, the joke will be on you when your resin doesn’t cure.

⭐️ BONUS: 5 things you should never set in resin

3.  Bubbles throughout your resin

No amount of hope and finger-crossing will ever keep bubbles away. But there are things you can do to reduce the number you have to deal with.

Choose the right epoxy type for your project. If you’re having a problem with bubbles in molds, you might not be using a casting resin. This resin type is specifically designed to let bubbles escape easily.

Then, mix your resin gently. The fewer bubbles you make at this step are fewer you have to get out later. Keep your whipping skills ready to make this delicious Florida-favorite dessert.

⭐️ BONUS: 10 tips for annihilating resin bubbles.

4. Sticky resin surface

If you’ve been multitasking while you’re reading this, I need you to come back to me.

Sticky resin is operator error 99.94% of the time.

Trust me on this. As much as we all want to blame it on the resin, epoxy will only cure as much as we help it to cure.

And that means you need to mix it completely.

And how do you do that? While mixing, scrape the sides of your resin cup and mixing stick, bringing that unmixed resin to the center. Keep doing this until you see your resin is clear and streak-free.

And if you’re absolutely freakin’ sure that you’re doing that, and you’re still having sticky resin, then you should check this casting problems resource:

⭐️ BONUS: How to fix sticky resin.

5. Soft-curing resin

So what if you’ve done everything right, and your resin cures soft? Like was solid after the cure time, but now that you’re wearing that resin bracelet, you can bend it with your hands.

It comes down to two things:

Your resin needs more time to cure, OR you’re using a soft curing resin.

The first problem is an easy fix. Keep the resin warm and give it another 3 to 7 days to harden.

But if you do that, and the resin is still dentable, then you need to use a different resin.

⭐️ BONUS: Why did my resin cure soft and flexible?

💡 Pro tip: Keep a journal

I don’t know how many times I’ve done something that has worked (or hasn’t worked) only to wonder what I did. Write it all down so you know what to do (or avoid) later.

Are you tired of resin casting problems?

Wasting your time and effort in making something you wouldn’t show anyone is aggravating. I know because I’ve been there.

It’s why I wrote the ebook Resin Fundamentals.  It shares the essential points you need to know to avoid the sticky, bubble-filled messes and instead make something that you can’t wait to show off.  Buy the PDF book now, and a link to download the book arrives in your inbox in minutes.

Unpublished Blog Posts of Resin Obsession, LLC © 2023 Resin Obsession, LLC

Like this post? You may be interested in  Cracking the Code on How to Mix Colors

41 thoughts on “How To Avoid The 5 Biggest Resin Casting Problems

  1. I have just started doing resin. I do ok until I file off any sharp edges. I then try to use glaze. I have ruined over 1/2 my pieces with this process. I have tried nail polish and Americana Triple Thick gloss glaze.It pitts the piece sometimes. It runs under it even when I am careful. What am I doing wrong.I have ruined so many beautiful pieces.

  2. Hi again! I guess I had beginner’s dumb luck when I started using resin… just a few large bubbles easy to dispense with. Now a dark resin cloud has moved in: I follow your instructions yet end up with a large number of tiny bubbles…some string together and look like pearl necklace. I use the straw/heat gun which doesn’t seem to impact little ones…is it that they haven’t yet come up to the top? Sometimes they get to the top and string together on the top edge. Help.

  3. @Dr Laura,

    The same thing happens to me as well. I don’t know what the physics of the small bubbles are, but they certainly don’t want to come out with heat or hot air! I get them out by scooping them up with one of our stir stix. A toothpick would work too, but it will take you longer.

  4. Hello,
    I have been having a problem with my resin. My pieces seem to be fully cured, they harden, retain their shape, and I can’t make imprints on them. However, after any very small amount of heat is added to them again, such as holding them in my hand for half a minute or trying to sand down the edges, they become rubbery and their shapes distort. Is this because of moisture? Are they just not setting properly? I would really appreciate your thoughts on this problem.

    – Mandi

  5. My first pours are cloudy and when the resin gets very warm that pouring is crystal clear. Also, sometimes after cured and removed from mold, the bottom is slightly pitted but the top is smooth and crystal clear. Whats happening?

    Thank you!


  6. When i pour resin over seashells they float to the top. Should I pour in layers even though the mold is shallow? Also, want to add sand. Which goes first…sand or resin?

    Thank you,


  7. Bought Xlarge bangle molds…too big and chunky. Can I pour half full to cut down on the size, will they still pop out ok?



  8. @Marcia,

    It sounds like your resin may be cloudy because it isn’t warm enough. Try warming the bottles in a warm water bath for 3 to 5 minutes before using. When you say the bottom is pitted, is this the surface next to the mold, or the surface exposed to the air?

  9. @Marcia,
    Yes, I would recommend pouring layers. That should keep your shells from floating. As for the order, it depends on what you’re trying to accomplish. What do you want your final project to look like?

  10. I have not used my resin for awhile and I noticed that Part B is getting thick yellow and seperated looking. when I used it my castings are rubbery and not hard after curing. Should I warm Part B before I cast?

  11. Another question please. I want to pour very tiny 3-D shoes with high-heels that are even more tiny for charms. Is there a resin that will pour into molds that tiny. what I have tried so far is too thick to run to bottom of mold so I come out with the shoe and no heel on it.

  12. @Bonita,

    I would suggest using the Resin Obsession super clear resin. It is a thin viscosity and will do well in getting into that high heel.

  13. @Bonita,

    It sounds like your Part B has water contamination. I would suggest either getting a new Part B or new kit altogether.

  14. I have been using resin over nail polish in jewelry. It looks great, everything is fine, but then a week or more later huge bubbles appear inside. Ideas? The bubbles don’t seem to be there initially, they show up much much later. Very large bubbles, too.

  15. @Kayleigh,

    I don’t have any experience with using it in that manner. You’re welcome to post a question in our forum though. Maybe someone else can comment?

  16. Firstly I have to say thanks, I love it when people do this kind of chat that really helps when there is a problem.
    I have 2 issues I would be grateful if you could advise on. Firstly I sometimes take my sculptures out of the silicone molds and they have a kind of crazy paving affect…not smooth, is this lake of mixing.
    Secondly I use alot of glow in the dark pigment powder and sometimes the lowest point in my mold gets the highest density as it falls to the bottom…I really don’t mind the effect but it can leave the surface very rough. Any ideas.

    I do work very cleanly with no moisture.

  17. @deborah,

    Your casting will impart the surface of the silicone mold. If a perfectly smooth item wasn’t used to make the mold, your castings won’t be perfectly smooth. To make your surface smooth again, you can try recoating with another layer of resin or seal with our resin gloss sealer spray.

  18. I used a Clear Resin product purchased at Hobby Lobby. I don’t think I mixed it long enough and the bottle cap jewelry that I did with 4th and 5th grades is tacky and never cured. Is there anything I can coat over the top of the resin to get a hard top coat? Will clear nail polish work? I hate to throw 18 bottle caps in the trash.

  19. Hi! How long would you say I should wait before applying resin to stones that have had nail polish applied to them? Thanks! 🙂

  20. hi! i’ve been pouring resin layers on top of oil paint and alternating them.. my last resin pour turned cloudy and now you can’t see any of the painting please tell me you know a way to uncloud the resin once it’s already poured ?!

  21. Hi! I’ve been using your super clear resin to make thin rings embedded with small objects. I’m consistently getting very tiny bubbles that create some porosity when I sand down the rough edge. They aren’t big air bubbles but even so when they are sanded they create tiny pinprick holes. Also noticing some cloudiness on some rings. I mix very carefully and weather is fairly warm out here. planning on buying the gloss to help with the pinpricks, any other suggestions?

  22. Hi! I’ve noticed that when transporting my pieces to & from craft shows; if the resin from one piece is touching the resin of another piece, they stick together. Do you have any suggestions to keep this from happening?

  23. Is it possible to cast a smooth part with epoxy (SmoothOn – 61D)? We are using a pressure pot to get the bubbles out but once it cures the result is a rough surface. This means having to take the extra step to manually smooth it out using a dremel.

    1. I have not worked with that resin, so I cannot say whether or not the resin is contributing to the problem. What are you using as your mold? If your mold surface isn’t smooth, your casting from that mold will not be either.

  24. I have a client I’ve sent a couple pieces (I make orgonite) to and two of her three pieces have started to go funky on her. When I sent them to her they were perfect, but after a couple weeks the first one started to peel off the crystal at the top and the second one started to “melt” any idea of what could cause this?

    1. What kind/brand resin are you using? Do you have a picture of a similar piece for me to look at?

  25. I was wondering if you dome a resin piece with a layer of resin and it cures and you notice you missed a spot can you double dome it?? I don’t want to ruin my piece cause it’s literally just a tiny spot but it is bugging me lol thanks a lot !

  26. HI, Can you give me some advise please? I set faux flowers in clear resin so to look like water. Sometimes the resin shrinks then pulls out the vase. Would you know what I’m doing wrong please? Or what I can do to prevent this please?

    Also, sometimes there is so much heat generated it cracks the vase. How can I prevent this please?

    Thanks EB

  27. Hello, I just bought a pressure pot to eliminate bubbles in my pieces. However, using it has led to other problems. When removing the pieces, I have found that the resin has pushed to one side of the mold and is thinner or not present on the other. Also, after removing a piece from the mold, I have found small craters on the bottom of the casted piece, as if someone took a small scooper and removed resin throughout the surface of the piece. Your help would be greatly appreciated.

  28. I have been making name tags on white sublimated aluminum. During the drying process the ink from the sublimated letters starts to spread or run. It collects in the epoxy because if I wipe it off the epoxy the tag looks fine.

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