10 tips for getting rid of resin bubbles

resin bubblesHand up if you hate bubbles in resin! (I have both of mine up in case you are wondering.) Nothing can ruin the look of resin quicker than finding a bubble in your finished project. Here are my 10 tips for avoiding and getting rid of resin bubbles.

1. Choose the right resin for your project.

If you are casting into molds, choose a resin that is designed for casting. They mix in a thinner viscosity, so it is less likely you will introduce bubbles into the resin. Even if you do, they also tend to release easier since the resin and hardener mixture is thinner. Thicker resins, meant for doming projects, generally hold bubbles, especially with thick castings. Doming resins are better suited for thinner pours.

Not sure which resins are doming versus casting?  Find out more here:

Casting resins
Doming resins

2. Cast resin in a warm room.

I realize that certain times of the year it can be difficult and expensive to run a heater all the time, but resin likes an ambient room temperature of 70 to 75 degrees Fahrenheit for curing. If it is a little impractical to heat your whole house or apartment, try heating a smaller space such as a bathroom or closet. Use something like a space heater to generate enough warmth so that the area stays warm during the entire curing time. You can also try making a resin ‘hot box’ for your projects. This works great for smaller undertakings like casting resin into molds and bezels. Here are some ways to make a resin hot box:

Resin casting in cold weather
Casting resin In cold temperatures

3. Warm your resin before casting.

Warm water in your microwave so it’s hot, but not boiling. Place your resin and hardener bottles in a plastic bag, then let the bag sit inside the hot water bath for five to ten minutes. Be aware, you do not want to get water in your resin. This could keep it from curing!  Note: By keeping the resin in the plastic bag, you will not wash off your label instructions and safety information. Warming your resin before use is helpful even if it is summertime as bottles generally are still cool to the touch. Be careful that you don’t overdo it. Yes, there is too much a good thing. If your resin is too warm when mix it, you will shorten your pot time.

4. Be careful when mixing.

You are not scrambling an egg! Mix deliberately, but carefully, while going along the sides and bottom of the cup. Sometimes when mixing large volumes of resin, it’s hard not to introduce bubbles that may not rise to the resin surface before casting or pouring. Know that you will need to have a way to get rid of these bubbles once you have cast the resin.

5. Make sure the surface you are pouring your resin in or on is also warm.

Temperature differences will produce surface tension which means bubbles can be trapped when the resin is poured. Gently warming your casting top/mold/bezel with a heat gun is an easy way to warm up the area. If you are working with molds that are oven-safe, you can also gently warm them (generally to 150F) before use.

6. Decrease the surface tension of a mold by dusting a powder on the surface.

A small amount of baby powder can work to reduce bubbles in resin. If you are using colored resin, you can even choose a powder that matches the color of the resin you are using. Use a delicate paintbrush to dust in the powder, then tap out any extra before pouring.

7. Roll the resin around your mold/bezel before completely filling the vessel.

This also helps to break the surface tension. If you do get any bubbles, they will be easier to pop now because there is less vertical space for them to move. You have them trapped!

8. For intricate molds, pick them up and try to ‘demold’ the resin several times during pouring.

This will let any trapped bubbles in creases to escape. You can see what I mean in this article: How to make a blue sparkle resin ring

9. Dip inclusions in resin before putting them into your mold/bezel. This also breaks the surface tension.

Once you have dipped them into the resin, put them into your mold or bezel on an angle, then move into place. By putting an inclusion flat onto a resin surface, you will likely trap bubbles underneath. This article shows how to put things in on an angle: How to make resin pendants

10. Once you have cast all your resin, go over it a final time with a heat source to pop bubbles.

I like to use a heat gun, but I know others will also use a butane torch or barbecue lighter. Please use caution when using a flame! You should have a fire extinguisher nearby. Also, know that excess heat may warp plastic molds.

Bonus tip:  If all else fails and find you are still struggling with removing bubbles from your castings —

11. Use a pressure pot.

With some resins (like clear polyurethanes) and/or large castings, the only way you can get rid of bubbles is to use a pressure pot. This is a system where your mold and casting are placed into a pot and pressure is created within the pot. This pressure makes the bubbles smaller than the eye can see. The pressure needs to remain on the casting the entire time during which the resin will cure bubble-free.

What else do you like to do to get rid of resin bubbles?

Want to learn other resin basics to help you make something that will have people saying, “Whoa, you made that?!”  Then you will want to get a copy of the PDF ebook, Resin Fundamentals.  It contains everything you need to know to go from confused to confident with resin.  Buy now and read it today!

Unpublished Blog Posts of Resin Obsession, LLC © 2021 Resin Obsession, LLC

Like this post? You may be interested in  10 reasons why your resin casting is a disaster and how to avoid them

54 thoughts on “10 tips for getting rid of resin bubbles

  1. If there is only 3 to 10 bubbles in a small jewellery project using high viscosity resin I use a syringe and large bore needle to suck them up. You only require a tiny amount of pressure. Placing the piece on a light box is a great way to see the bubbles.

  2. Hi Katherine,
    Thank you for all of the advice and support you provide for beginners! I just cast my first trial pieces. I uesd Art n Glow Clear Casting Epoxy Resin in pendant size silicone molds, no additives or inclusions to start. I followed all instructions, and the only problem I had was the presence of numerous micro-bubbles throughout the pieces. They did not cling to the sides or rise to the top, but rather were evenly dispersed throughout the casts, too small and numerous to manually remove. Do you have any advice on avoiding these in future casts? Did I mix the resin too vigorously? Should I let it settle for a few minutes before pouring into the casts? Will a heat gun remove those, or does that only work on surface bubbles? Thanks!

  3. Thank you so much for your helpful hints!! I did lots of no nos in my mixing resin!! I will do it your way the next time!! Excellent ideas. I mix resin in my jewelry making & belt buckle blank making to seal my goodies I use in them.

  4. Will a hairdryer work to warm the surface and to release bubbles? I’m covering a flat surface made of walnut. It is a corner desk in my kitchen. Thanks.

    1. I don’t think a hairdryer works as well. It doesn’t get as hot as a heat gun and has more air force than a heat gun, which can blow the resin around a lot.

  5. Any tips for bubbles when using a mold that closes? For example bracelet/bangle molds . I keep getting bubbles at top where the mold closes. I don’t see them until next day when I remove the bracelet.

  6. I have seen several times on YouTube that someone is using some kind of spray over the resin in the mould before curing. I assume it’s also for popping the bubbles but what kind of spray is this?

    1. That’s not anything I do. I have had a few people ask me about doing that with alcohol to pop bubbles, but that alcohol can impact curing. It’s not something I recommend.

  7. thank you for sharing your tips!…I think I now know why I get so many bubbles in my mold castings….I’m too fast at stirring…I will now deliberetly stir my resin!

  8. I am a retired Florist of 56 years and have been preserving flowers, by the Freeze Dry process for 28 years. I had these two companies run at the same time, but I just do the preserved flowers for now. I have had many requests for putting preserved, color treated (so never any fading through the decades) flowers into resin…especially single flowers…like the “Rose” from an casket, which becomes very meaningful…like into a 3″ round paperweight. I am old and like to learn new things…but need to be perfect! I also have flat, small cake pans, in the shape of 7″ hearts made out of silicone and circles, so I can put a few more flowers inside, to hang on a wall. These will be maybe 2″ deep.
    My resin kit is RTC Supply Company, Clear CAsting craft resin, which says the resin can be used for bigger molds. I have painted many paintings with acrylic paints and covered them with a thicker resin to get that 3D look…very shiny and a thin coat. This resin that I mentioned is not for that… I guess my question is “do you think I have the right resin to make these bigger molds?”. Id not…can you recommend the right one? Also, can I pour the resin in smaller layers..let to harden…pour another layer on top etc….rather than one big pour? I have read and printed out the 10 mistakes in resin…but have these questions. I’d appreciate your advise.

    1. Hi Ali, I’m afraid I haven’t used that resin, so I don’t know how well it will work for your project. Yes, you can pour your resin in layers as you describe.

  9. It’s not a good idea to use a heat gun or hairdryer to pop resin bubbles because you can easily blow dust, etc. into your resin without noticing. A torch held a good distance away or a grill lighter is your best bet.

  10. To each their own. It isn’t a chance I am willing to take, and in the 7+ years I have been working with resin, I have never had a problem with setting anything on fire. Common sense and safety precautions make sure of that for me.

  11. Great advice and ideas here. My first few tries with resin jewelry were excellent but now I am suddenly getting tiny air bubbles in all my mixes. They are evenly dispersed and I have tried everything to get them out. No luck. My resin just looks cloudy. It is warm enough (summer in South Africa) and I am mixing slowly and long enough. I am a retired analytical chemist so I should know about mixing by now 😊 Could it have something to do with opened bottles of resin and hardner? I only opened them two weeks ago but I have used quite a bit of the contents.

    1. Hi Marcelle, I wouldn’t expect that to be the problem. I’m teaching another online jewelry class here in a few weeks. I’m going to spend a lot of time talking about bubbles. If you want VIP access to the class, you can sign up here: http://bit.ly/32CuuxC

  12. Thank you, Katherine! I’m building a small pressure tank right now. Will let you know if I don’t get blown up first.

  13. thanks so much for the valuable information you have inspired me to do resin in my future days when I’m older I’m only 12 right now. please do more I would love to look into it.
    I only did resin for my school research project because the information you have on your websites inspired me to look into it more.

  14. For small jewelry/ bezel filled projects, I use a straw to carefully blow on the surface of the resin to remove large air bubbles. Seems to work, but my last bezel had lots of micro bubbles, barely seen, but annoying. Thanks for your info, think I’ve been stirring too quickly to cause the micro bubbles. Thanks for the wonderful tips!

  15. These are great tips, thanks.
    I’ve just poured some clear resin for the first time (usually use Mica colouring) and I have bubbles. The resin has almost set so I can’t get them out with a heat gun. I’d sand them out when it’s harder but the resin is inaccessible for a sanding tool in certain parts. So my question is – can I add a layer of resin that will fill the bubbles? Or is there another trick?

  16. Hi, great information and so generously given! Thank you. My question is, can one use a sponge ‘paintbrush’ to apply resin on to a thin plastic surface? Many thanks. Regards Di

  17. Hi, I’m flashing a chef’s torch over pendants but it can cause a ‘crazy paving’ effect On the curing resin sometimes. Is this perhaps just because I’m in too close with the blow torch?

    Also, do certain colourants/acrylics cause a strange crinkly surface once heat it’s applied to domed/coated resin pendant? Or a kind of oily/smeary looking dried finish?
    I use GlassCast 10/50 which I find very easy to work with as a rule.
    Many thanks

  18. I am new to resin, but found I like using UV resin. Do your tips also work for UV resin. I have bought 2 different brands of the resin and both seem thicker than the epoxy resin. They are both supposed to be casting resin

    1. Hi Pam, I’m afraid I don’t have enough experience with UV resin to know whether or not these tips will help.

  19. Hey everyone. I’ve seen several websites or videos, ppl recommend spraying the top of the epoxy, after in the mold, with alcohol to get rid of bubbles. Can u pls tell me why this would or would not be a better idea than using a heat gun??. I saw this briefly mentioned a few places on your site, but I didnt find in detail why or why not use alcohol. Thanks so much!! Have a great one!!

    1. Hi Amy, alcohol adds moisture to the resin. It can make your resin cure bendy or soft if you use too much. It’s also flammable, so I definitely wouldn’t use it as a spray, then use a torch to go over the top too.

  20. Using a wooden stir stick will add to your bubble problem since they’re quite porous. Using a plastic or silicone coated stick will cut down that problem tremendously (and they’re reusable!)

  21. I have had some luck with a large plastic straw, and blowing warm breath on the bubbles. Careful though warm breath can condense inside the straw and form water droplets.

  22. Hello Katherine, I love the tips, thank you so much for the guide!

    I have a question about the bubbles, I have a large (around 35cm*35cm*15cm) resin project that includes plant material. I don’t have a heat gun, so I was thinking I could use a hairdryer on high heat and blow this over top (not directly on the resin’s surface) to get rid of bubbles. Would this work? And would “tapping” the mold be useful to get the bubbles to rise? We used to do this for frothed milk to get the air bubbles to rise to the top. Any advice you could give on Resin brands would also be much appreciated, if you can.

    1. Hi Rosh, the trick to getting such a large project bubble-free is going to be in the resin you use. For a project like this, the Resin Obsession deep pour epoxy is ideal. It mixes in a way to easily release bubbles for big projects like this. You can buy it in our store here: https://shop.resinobsession.com/products/deep-pour-slow-cure-clear-epoxy-resin-for-river-tables-1-1-2-gallon-kit. You can try a hair dryer to get the bubbles out, but I find it usually blows too hard and creates a mess.

      1. Thank you so much for replying so quickly, I went to purchase the resin but unfortunately it can’t be shipped to the UK :/ Thank you for the information though!

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