What to do with yellowing resin? – Can you use it?



What to do with yellow resin

by Penny Reid

What do I do with yellowing resin?

I’ve heard mixed experiences with using yellowing resin.  I have heard it won’t cure or that it will only get deeper yellow when cured.  I also read the opposite — that it gets less yellow when cured. Having some 1:1 epoxy resin with yellowed hardener on hand, I thought I would test it out.

This is my resin with the very yellow hardener getting mixed:

yellow resin

I used Resin Obsession Opaque Colorants – one purple and one white. I left one without colorant to see if the yellow changes at all when it cures.

colorants added to resin


Time to break out my favourite ghost mold!

ghost mold for resin

fill the mold

]Here they are cured. Both the ghost castings with colorants are perfect! No trace of a yellow tone at all and they cured perfectly. As expected, the clear casting stayed yellow.  It didn’t appear to get darker or lighter as compared to before casting.

This was a fun experiment and it’s good to know that I can still use resin even when it’s yellow.

cured resin

What has been your experience with using yellowing resin?  Were you happy with the results?

resin castings made with yellow resin

Unpublished Blog Posts of Resin Obsession, LLC © 2020 Resin Obsession, LLC

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23 thoughts on “What to do with yellowing resin? – Can you use it?

  1. Thanks for doing this experiment! It’s really good information, not that I ever let mine turn yellow. ;}

  2. what about using resin which is specifically for wood?
    the old yellow resin might work for antiquing brooches etc

  3. This stuff will indeed cure properly. The yellowing comes from the oxidation of the hardener. This example shows what happens with no colorants and opaque colorants.

    Personally, I have found that clear colorants get a cloudy finish when the hardener has oxidized.

    In the past … I have not cared about the oxidation. I mostly cared about the wear resistance and the toughness of the finished product. I was using this stuff to do carbon fiber and fiberglass layups.

    Now … however; I have invested in an Etsy business which uses Katherine’s special clear resin. The Resin Obsession clear resin is absolutely 1st rate!

  4. Great to know, I had the same issue with a forgotten box of resin, I tried it with some steampunk pieces it actually gave a nice antique look to the piece,so don’t toss it.

  5. I love using yellowed resin-I actually add more yellow to it and a hint of red to cast it like a piece of amber-I have even placed dead insects in the cast-I have also added small pieces of iridescent paper and dryer lint (clumped in some areas to let the iridescent paper show thru like a vein, the lint looks more like stone)

  6. I love to make the yellow resin look like Amber with insects in it for the top of my walking sticks or canes. You know the Jurassic Park thing.

  7. my resin cuff bracelet cured just fine but gets rubbery when its on my arm due to my body heat. Any suggestions?

  8. I’ve decided that the yellowing actually would make my vintage work look even more authentic with the yellowing aspect 🙂

  9. Thanks for reporting on this. I probably would have saved it for mixing with an opaque colorant, so this confirms that would likely work well.

  10. Thank you this information and doing the experiment. I too had read that once it turns amber that it can no longer be used. I have a few bottles of different brands of resins, because I was trying to find a brand that is heat resistant for the coasters I want to make.

    1. If you opened the resin, then didn’t use it for awhile, the oxygen in the air at the top of the bottle can cause the yellowing.

    1. Unfortunately, even coatings with UV protection aren’t 100 percent effective. You should expect that your resin will yellow with time.

  11. Great post! This may sound odd, but in the cake baking world, sometimes a tiny bit of purple is added to buttercream to make it whiter (it’s yellow because of the butter). It works well! I wonder if anyone has ever tried that with resin.🧐

  12. Resin also crazes after time… I do wonder how long the beautiful dried flower pieces in clear resin will remain beautiful?

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