More resin troubleshooting – five most common resin mistakes

Common resin mistakesIf you have ever used resin only to get less than desirable results, you’re not alone.  While resin is a fun and versatile way to make jewelry, it can be a fussy beast as well!  These are a few of the most common resin troubleshooting problems and what you can do about them: 

1.  “Stains” or dark areas on embedded items.


moisture stains on paper

This is when you embed papers or porous items into your resin castings only to see later that the item has stains or dark areas on it like it is wet.  This happens when the resin soaks into the paper.


Coat any paper or porous items ahead of time with a clear-drying white glue such as Ultra seal glue or an aerosol sealant such as the Castin’ Craft gloss resin sealer spray

These techniques are helpful for how to papers and other items sealed for casting in resin:


2.  Resin castings are cloudy or full of bubbles.

This can happen when the resin reacted with the embedded items.  The resin can react with your embedments, especially if you are talking about vintage papers (lots of acid!).

There are a lot of reasons why bubbles can happen in resin.  Here are 10 tips for getting rid of bubbles in resin.


Coat embedments in sealant before using.

Make sure the resin is warm before mixing.  Put both bottles in a warm water bath for 5 to 10 minutes before pouring.  Be sure your containers are dry before working the resin to avoid any water contamination.

Are you trying a new colorant or addition?  The resin may be reacting with that item.  Once again, make sure all additions are dry.

You can watch some of my best resin troubleshooting suggestions on how to avoid bubbles in resin:

3.  Resin is not fully cured after the suggested curing time.

This can be anything from still a bit sticky on top to a big goopy mess.


Follow label directions precisely.  Do not add more or less hardener and measure accurately.  While it is popular in a lot of other blogs and youtube videos, I never suggest using the caps to the resin bottles as measuring tools.  You cannot get an accurate measurement this way.  Use the proper size mixing cups to measure and mix your resin.

Make sure your mixing utensils and containers are dry.  Resin hates water!

Store your resin in a climate-controlled environment.  Having resin in an area where there are big temperature swings (such as a garage or storage unit) can allow condensation to form on the inside of your resin container lid.  This moisture then drips into your resin.

Make sure you mix the minimum amount of resin needed for the chemical reaction of curing to occur.  For example, if you’re working with a 1:1 resin to hardener resin kit, you cannot mix two drops of resin to two drops of hardener and expect it to cure.  Resin curing is a chemical reaction that requires a minimum amount of each component for it to occur.  Our resin buying guide is a PDF with all this information for the resins sold in the Resin Obsession shop.

Mix thoroughly.  This video shows you how:

If your pieces end up being just a bit tacky on top, you can try sanding them down and recoating them with resin.  If your resin is a semi congealed mess, there is not any way to save that resin.  You can try to scoop it out of the mold and clean with home improvement store acetone (wear gloves when doing this!) to remove the leftover resin, but it may be easier for you to toss the mold and start over.

4.  Resin sticks to my mold.

Assuming your resin is cured, you can try these resin troubleshooting tricks, otherwise, see number three above.


First and foremost, I always recommend using a mold release — even with silicone molds.  It’s a good habit to get into and prolongs the life of your mold.

If the cured resin is stuck to your reusable plastic mold, you can try placing the mold in the freezer for a minute.  Remove the mold and see if you can ‘slap’ or ‘break’ the resin out of the mold.  (You can try smacking the mold on a hard countertop.)  If the resin doesn’t come out, you can try putting the mold in the freezer for another few minutes.  In my experience, if the resin doesn’t come out after 10 total minutes of freezer time, it’s not coming out.

If the cured resin is stuck to your silicone mold, I’m afraid there’s no way to get that out.  However, that brings me to another important point:  polyurethane and silicone don’t play well together.  Personally, I have never had a problem with properly cured epoxy or polyester resin sticking to a silicone mold.  The times I have heard about resin sticking to a silicone mold have always involved silicone and polyurethane where a mold release was not used.  Of course, if you’re casting silicone into silicone, you will absolutely need to have a mold release, otherwise, you will create one large block of silicone.

5.  Resin gets hot and cures within minutes.

There is always a little bit of heat when resin is mixed due to the exothermic nature of the reaction and curing.  Excess heat, however, will cause the resin to cure very quickly.


Use the proper mixing utensils and containers.  While I understand it is tempting to use old plastic bottles, party cups, and styrofoam containers to mix resin, these items have chemicals in the surface that can accelerate the reaction that occurs between the resin and hardener.  Try to use plastic cups designed for resin.

Do not add more hardener than is recommended.  This will speed up the reaction and can cause the resin to cure very quickly.

Do not mix more than the recommended mixing amount of hardener and resin together at once.  This resin buying guide contains a PDF link with the information for the resins sold in the Resin Obsession shop along with their minimum and maximum mixing amounts.

Want more to get more resin troubleshooting advice?

Get a copy of the instantly downloadable ebook Resin Fundamentals. It covers the resin basics to get you up to pro speed in no time!

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

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

113 thoughts on “More resin troubleshooting – five most common resin mistakes

  1. @Gizem, Wipe your containers and stir utensils while they are still wet with a paper towel and acetone. (Be sure to wear gloves when doing this.) If they have dried already, try soaking them with a very hot water and Tide laundry detergent.

  2. @Katherine, great tutorial as always!!
    I realize this is a tutorial for trouble shooting, but the snoopy is a perfect example of how to salvage a piece you might otherwise throw away…
    No need to through out most resin pieces that didn’t quit turn out. With a little creativity you can salvage most pieces.
    The scene is a winter/Christmas scene. The seepage is at the bottom & a bit at the top…
    Add a bit of fake snow mixed with a tad of white glitter & glue on to the bottom to cover the bottom error. Add glitter or a small bow to the top error. Let all of that dry overnight and in the morning pour a doming layer. Tada… problem solved.

    1. Can the shape of the mold cause it to hear up more and not cute correctly?
      For example: I mixed a batch of resin and poured half into a flat round mold and the other half into a deep square mold. So I’m using the same resin for both molds, but the square one is very hot and the corners of the the resin have shrunk down, (never seen this before before).
      I use the circle mold all the time for coasters, thought I would try the square for paper weights, but not if this happens. I just poured and inked so I don’t know how it will fully cute, but the coaster looks fine.

  3. hi ,the resin that i use is 100:30 ratio so recently i did two sets but both didnt cur properly i used a butter knife to scoop the resin out from the molds and its cured half way and still rubbery do u think it’ll cure in time to come its been three days now , …

  4. @Amali, if the expected cure time has passed and your pieces are rubbery, giving them more time isn’t going to help.

  5. Will the exposed resin at the top of the mold harden or will it remain tacky – and in that case what can I do to seal and harden the top of the mold.

  6. Thanks – I turn pen blanks and some of them come with a tacky surface which turns away with finishing the blank and I guess those are not acrylic


    FYI – I intend to encapsulate butterfly wings in resin – thin sheet – soften the cast and wrap it around a pen tube. The next step is to encapsulate the entire tube butterfly wing wrap and all in clear resin mold (rectangle), harden, turn on a lathe, and voila.

  7. This is going to sound crazy but I am in serious need of help. I have been working on a large piece but have never used resin before. I am familiar with silicone, and assumed it would be a similar process. Instead of doing a test, as the manufacturer recommended I jumped straight into the large piece, miscalculated the amount of hardener for the first batch which leaked out of the 2m long wooden container onto my studio floor. The space has terrible ventilation and the fumes are intoxicating. In a completely misguided attempt to conceal the fumes I layered wet clay on top of the wet resin, which has obviously made my problems worse. I have now tried to scrape the clay off the floor and have poured the remaining hardener, a significant amount, onto the floor in an attempt to get rid of the fumes, and for some unfortunate reason I poured a considerable amount of water into the mix. Having read the comments on this site I now realize what a foolish decision that was. I’m not sure exactly what type of resin I have been using but since it was for a large table I would assume it is a polyester resin as it dries very hard with a slightly tacky surface. I have tried cleaning the wet resin with acetone but that does not seem to help, especially with the fumes and my throat is now raw from inhaling the fumes. Is there any advice you can give me that can help me clean/dry the resin to eliminate the fumes? I would prefer not to use any more toxic chemicals but would appreciate any suggestions.

    1. Hi Megan, assuming you are using a polyester resin, those fumes can last a long time. You need to completely open up your studio and get as many fans as possible to get the fumes out of there. The only way I can see getting the mess out/off of the floor is for someone (like a contractor) to sand it down. That is going to require that person to wear the appropriate protective gear in addition to properly disposing of the waste. With any luck, you may be able to use a crowbar (or something similar) and a mallet to dry to break up the resin. (It’s the technique you would use trying to get tiles off a floor.)

  8. I was wondering if there was an easy way to remove metal charms from resin cabochons that you screw up? Sometimes my resin doesn’t set properly and I’d hate to waste the charms I’ve dropped in the resin. Any help would be much appreciated.

    1. If the resin is completely cured, I’m afraid you are out of luck. If it is still syrup-y, you can try soaking in acetone.

  9. Hi,

    I got confuse about this;
    Make sure you mix the minimum amount of resin needed for the chemical reaction of curing to occur. For example, if you’re working with a 1:1 resin to hardener resin kit, you cannot mix two drops of resin to two drops of hardener and expect it to cure. Resin curing is a chemical reaction that requires a minimum amount of each component for it to occur.

    How this can be if the ratio is 1:1, I cannot measu equally ???

    Also, instead of leaving the resin in warm water, it not should be better if I warm it up in the micro wave for few seconds?

    Thanks a lot


    1. Hi Osmar, mixing together two drops of resin and two drops of hardener are unlikely to produce enough heat to allow curing. You will need to ask the manufacturer the minimum amount of each, i.e. 5 ml of each for example, that you will need to mix in order for curing to occur. I would not warm up the resin in the microwave as that may get it too hot in spots.

  10. Hi I’m in trouble! I need your help! I am making cubical crystal clear resin awards. But before I take the piece out omg the mold the resin crashes inside. It brokes when it is still hot, I don’t know what Am I doing wrong 🙁

    1. It sounds like the resin is getting too hot. Are you mixing no more at once than the manufacturer recommends?

    2. do not worry! When resin heats up it will cure faster but still give it a day to fully cure. It wont effect the outcome it will just get very hot but once it cures it will start cooling down.

      1. I wouldn’t say that quick heating doesn’t affect the final outcome. Sometimes these pieces can crack or get a ton of microbubbles that will make the final casting cloudy.

  11. I am trying to pour resin in a small glass bowl with a rose into to make a paper weight I have dried flowers but the minute the resin starts to set up the flower turns brown help

    1. I read somewhere about sealing flowers, plants, or candy with something, but i can’t remember exactly where I saw it

  12. HI

    Just a question – do all mouldy need to be plastic or silicone or is it possible to use aluminium mounds e.g. Old fashioned jelly moulds?

    1. I have not tried them for resin molds. Resin likes to stick to metal, so you would definitely need to use a good mold release. Even then, I question whether or not the mold is flexible enough to release resin.

  13. I need help recently started pu resin on the paintings but as it dries valleys appear where resin has separated I try to push more resin back on to those areas but doesn’t help , what am I doing wrong?

  14. The resin doesn’t adhere very well on the edges (the rounded part) it looks like fish eyes the way resin works with silicone but I clean my edges just like the front. Suggestions?

  15. I’ve used Marine epoxy, Countertop (I Dont remember the brands) and as of late Art Resin. I get the same average with all of them.

    1. So the good news is that you are using doming resins, which should work. Unfortunately though, it sounds like your edges are a little too curved for the resin to want to stay. Have you tried creating a tape dam around your edges to help keep the resin in when you pour?

  16. I have never been able to stir my resin and not get air bubbles in it. How do you do that? I do the same thing you do in the video.

  17. Ok I know this is trouble shooting resin but I need a more experienced view. I took some resin pieces that I was going to throw away to school. People really liked them and I got commissions. I got into resin a month or two ago and most of my pieces turn out pretty good, save for the occasional tackiness and bubbles. I’m not trying to market them as professional quality and I tell people this but I’m worried that I might be getting over my head. I don’t know if I should do the commissions and stop or try to get more. Do you have an opinion?

  18. Thanks for all your tips. I’m new to resin but I noticed on my 2 resin pieces, canvas and wood panel that they both end up with less resin on all edges. I leveled them and I’m puzzled why this is happening? Tks

  19. Thank you Katherine for all the great info. For 12×12 I used 5oz for top n sides. Should I re-do and extend painters tape up n above edges to hold resin in? I love the all over look though but willing to giv it up.

  20. PS I hav a tip I wld like to share. Vaseline works great where u don’t want resin. It peels right off. I used it on my underside edge of my wood panel b4 I resined.

  21. Im using Smooth Cast 305, i measured everything right but it hasnt cured properly and is soft and there is some excess oils. Ive taken my casts out of the molds but there is some oils and rough bits of resin left behind. Whats the best way to clean the molds out?

  22. Hi, please could I ask for some help. Many years ago I poured resin (over paper pictures) on the bottom of a tray. I have now found out that the painting under the resin and paper was done by my grandmother. I want to know if there is any way of now removing this resin, after all this time, without destroying the painting underneath. Thanks.

    1. Unfortunately I don’t know of a way of removing the resin where the painting won’t be damaged as well.

  23. I am casting in a silicone mold. The top part comes out crystal clear but the bottoms and sides are dull. Any idea why? I am using a mold release and made sure it was completely dry before I poured.


  24. Hi I have done an acrylic pour painting on a stretched canvas. I used silicone in some of the paint. I used the product Glaze Coat High Gloss Craft Resin. I mixed 1:1, stirred for 6 minutes and all of that.
    The result I got is blocky. It resembles what happens if you were to spill Sprite or 7-up on a table and let it dry. The surface is smooth to the touch and not tacky. It just looks like a Sprite spill… any advice?

    1. Hi Kayla, it sounds like you have some divots in your surface. Do I understand that correctly?

      1. I am attaching a pic as I am not sure what it’s called when this happens.


        1. Hi Kayla, it looks like ‘fish eyes’. Did you wash your painting surface before applying resin? Silicone leaves behind a residue that can push away resin.

          1. Use a good detergent (I like Dawn dish soap) and allow to throughly dry. Some will go the extra step of rubbing down with alcohol to remove any remaining residue. Allow to fully dry before applying more resin.

  25. I’m trying to set a piece of fruit in a resin block, but the temperature of the resin burns the fruit as it set, leaving a black burnt mess inside. Can you help?

    1. Hi Brian, I want to help you with your project, and 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. I can set you up for a 15 minute consultation call. If you want to send an email through our contact page, I am happy to respond with prices and availability.

  26. Hello ~
    I just had a question regarding a problem I’ve encountered trying to use EnviroTex Lite Pour-On Resin.. (I have a photo to illustrate my issue, but I am unable to attach a photo to this message). Basically my issue is that when the product dries, it will ‘retract’ in certain areas and not dry smooth… (I call it the “Freddy Krueger effect”). Please note that I am also pouring on top of an already resin surface, (in an attempt to ‘restore’ or cover blemishes), but I have sanded the surface prior to use (1000 grit). I will also use a propane torch to eliminate the tiny air bubbles.. yet somehow, I am unable to successfully get it to cure smoothly. Any advice/tips as to why this may be occurring or what I may be doing wrong is greatly appreciated!
    Thank you!

  27. Hi Katherine,
    Great article, thanks!

    I’m preserving dry flowers in resin using spherical molds and my first batch was awesome. However the second batch became a goopy mess inside the sphere, like I can press the ball on the surface and feel the softness inside.

    I think I might have not mixed enough (3 minutes according to the instructions) or the temperature might have decreased because I live in a warm country and I turned on the AC in the middle of my process.

    I have a question regarding resin curing. When I pour the resin on many tiny flowers, they rise to the top and I continuously poke them so they stay inside. Does that mess with the resin curing? Could this be a reason why my resin was goopy? Plus if I fill the resin mold in 2 parts to solve this issue, meaning I fill half the mold with resin and flowers and let it dry, then I mix more resin and pour it on the top, will it be a problem for curing resin?

    Thank you very much,

    1. Hi Tooba, it sounds like you are working hard to get your resin and flowers to work together. Awesome! I want to help you with your project, and 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. Best, Katherine

  28. I really appreciate your video on using paper with resin!!! I’m getting ready to do a pour using a small amount of paper, and found your video very helpful as I only have 1 picture to use and don’t want to mess it up. Thanks again 👍

  29. Hello,
    I am pouring 1/8” layers of resin over dried flowers in a mold. This last pour dried with a leather look. I wait 24 hours between pours. I just want to make sure my last pour will dry like glass. Any suggestions? Thank you, Joyce

  30. I resigned to of my Pebeo tile creations using Pebeo brand resin glaze and missed a few spots. Can I reapply resin and does it need to be the same brand? Does it need days if curing? Just did it yesterday. I don’t have any resin left.

    1. Hi Teresa, yes, you can reapply another layer of resin. While I haven’t used Pebeo resin, I have never had a problem applying one brand of epoxy resin over another brand. You can apply another layer right away or wait until the first layer completely cures. If you wait until it cures, be sure the surface is clean before applying a new layer.

  31. If a section of my painting repelled the resin can I go over that section if I wash it first

  32. I’m pretty sure I did not adequately clean my surface. I am going to let the project cure then wash dry clean with a small amount of alcohol and recoat

  33. Hi. I recently used a resin release bottle and in 24 hours my mold never completely dried. It’s losing resin as I test it out. It’s not in the form anymore. Is there anything I can do to harden it quicker?

  34. What should I do!!!
    I was using a silicone mold, perfect 1:1 ratio & I thought the design was 100% cure and dry and when i took it out the mold, it was Dry but I was still able to bend it. Is the design ruined or can i continue to let it sit and it’ll harden up?

  35. Hi . Ive just started out with resin and have had a couple turn out ok and some not . I hqve tried a different couple resins And just not having much luck im weighing the resin out like suggested and mixing for 3/4 mins . Problem i have is i have so very gloopy resin in mould that have been there for almost 24 hrs there so sticky they don’t pull away from the sides … my question in will i be able to remove and clean my moulds or will they have to be chuckled?

    1. Hi Jo, I’m sorry this is happening to you. You can try putting them in a freezer for 10 minutes. Perhaps they will freeze hard enough that you can demold.

  36. Hi Katherine, I’ve just had my first disaster with Resin. My “studio” room has been around 64-68 degrees F, I have a fan heater and a thermometer at my table and try to keep the area at least 72 F. I have a water bath and heat the resin up to 26-27 degrees C, which at most is 80.6 F, and is only the bottom of the bottles. By the time I had pulled the bottles out, dried them off, and started to pour them, they didn’t seem warm to the touch. I mixed them in my usual OCD measuring and mixing style, and then was dribbling clear resin on a cab for a third pour and my hand holding the resin got hot. All of the sudden I had a gloopy off white solid in the cup and the cab I was sealing was developing a layer of white. I cleaned up the area, and started another pour. (No I did not put the bottles back into the water bath , , ,) This time the reaction was faster, and the clear liquid I had poured into a 30 ml cup with black ink drops was no longer liquid. Neither was the new gloopy off white solid in the big cup. I can’t believe that there was too much heat, nothing cracked. Any ideas? Bad batch of resin and hardener? This didn’t happen last week, the bottles I used today were new & unopened.

    1. Hi Vicki, how weird! It definitely sounds like something sped up the reaction. Maybe try again without warming the bottles first.

  37. AHA! My subconscious supplied the answer overnight. I had one box of Alumilite Casting Resin, and I bet when I get to my workroom I’ll find that I opened it by mistake. I thought A & B were not as viscous as they usually are . . . LOL.

  38. Hi there, I’m a newby and have made eight wooden coasters as a gift. I inset copper and silver coins into them from our pre decimal days, placed paua shell around the edges and finished them with a coating of dome epoxy. They turned out lovely except I made one late mistake by inadvertently touching the top on two of them and leaving a couple of finger prints. Will they disappear if I just pour another coat on them or could I perhaps smooth them out with a touch of isopropyl alcohol?

  39. Katharine, Our Museum owns 3/4s of a beer mug from 1869 Eldorado, Oregon. My plan is to make the missing glass parts out of wax, assemble into a round top and make a mold, matching the wax cut lines to the break in the glass. I then hope to get a clear epoxy resin and pour into that mold and when set, glue to mug. I’ll use a similar procedure for the missing handle (using photos of old mugs for shape) and glue it to the mug. This will then be put on display. Any thoughts?

  40. Hi! I made a resin mold over wedding flowers and began sanding it down to find that a few layers didn’t dry properly. The gooey resin clogs up the sand paper and I’m not sure how to make it look clean again. Any tips on how to make the resin hard or get it to come off easily?

  41. I am trying to make small snowflakes from a candy mold. The shapes themselves come out great. The issue is that the surface of the resin that touches the mold itself is dull. The surface that is exposed to air, is beautiful and shiny. It is the mold itself that is causing the dull color? Do I need a different mold?

  42. Hi quick question I was hoping someone could help me resolve. My molds have marks on them from cleaning, they are just smudges so to say on the surface of the mold. they are transferring to every product I make from the mold. I have tried alcohol to no avail, also dawn. is this something a mold release could solve? or is there any other way to get the marks off?

      1. Hi I have a question! Once my resin has cured, after a while I start to see round circles forming on the top of the resin creating a weird bubbly pattern. The resin itself is clear, it’s just the top layer. I have tried changing the humidity or my room, warming my resin before mixing and mixing for over 5 minutes but these circles still form after about a week. Do you have an suggestions, I would really appreciate it!

  43. Hello. I was given a molded resin “board” as a gift. I realized that there are a few sticky areas on it. I was told by someone that I could rub the sticky areas with a light oil and then wipe but it didn’t help. I don’t do resin art but I do painting and poured painting and have a gloss sealer that I spray on my poured paintings and get a great gloss finish with it. Could I use the spray sealer over the board to alleviate/cover the sticky areas? Thanks for any help you can give.

  44. Hi I been turning resin bowls mixed with wood and my resin has been breaking off in small pieces I must be doing something wrong

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