7 Reasons Your Epoxy Resin Is Yellowing [And How To Fix it]

Here is why your resin is turning a yellow color. Sometimes you might notice that a beautiful resin pour that you created is now turning yellow. This can happen months or years after pouring the resin. You might also notice that the resin is turning yellow inside the bottles even though you have not mixed the hardener and resin together yet. We are going to discuss why this happens and why the resin is turning yellow.

Yellowing epoxy resin is definitely a concern. Especially if you have white faux marble countertops that have been poured with resin, or a high end geode resin art piece that is mostly white. Since resin is fairly expensive, it's a shame that it is prone to yellowing.

Unfortunately, most companies don't tell people that their resin can yellow. It can be an expensive lesson, especially if you are in the resin business and selling resin creations, resin countertops or resin art pieces and jewelry.

Epoxy resin turns yellow due to several reasons. The resin may have heated up too quickly when curing or there may have been a reaction to the colorant that was added. Poor quality resin will turn yellow within a few months, especially when it is exposed to UV light.

WHY RESIN IS TURNING YELLOW

1. Poor quality epoxy resin will yellow more quickly

Choose an epoxy resin that has a good reputation of not yellowing. You will have to do some research in Facebook groups and reviews. There are quite a few popular brands that say their resin does not yellow, but most will over time.

2. Resin that is constantly exposed to UV light will yellow

Try to keep the resin from being exposed to direct sunlight. If you are selling art pieces or jewelry, include an insert letting your customer know to keep their pieces out of the sun. Resin that is constantly exposed to sunlight is prone to yellowing more quickly.

3. Adding colorants that are not compatible with the brand of resin may cause yellowing

Sometimes it's the colorants that are causing the epoxy resin to yellow. Also, if the brand you are using comes with their own powder colorants it might be best to use their house colorants. Companies such as ArtResin and Let's Resin have their own colorant brands that work very well with their resin.

See ArtResin's resin and colorants here

See Let's Resin resin and colorants here

There are some tried and true colorants that will work with pretty much any resin which is discussed below in the fixing yellowing resin section.

It is also good to know that titanium dioxide, which is a white powder, can cause a reaction with the resin and cause it to yellow more quickly.

why resin is turning yellow

4. Resin that heats up too much when curing or mixing can cause it to yellow 

There are certain resins that are specifically formulated for deep pours. If you are wanting to pour anything deep, like a lamp base or deep section for a river table, then be sure to check that the resin you choose is made for that.

Using a regular resin may cause the resin to heat up to the point of melting your form. That will most likely cause yellowing. So be sure to do your research about what types of resin to use for deep pours.

5. Misuse of a heat gun can cause burning and yellowing of the resin

Many artists and resin creators like to use a heat gun to move the resin around. This is especially popular for making lacing effects and for geode resin art.

Using a heat gun is totally ok for this, but make sure you are not burning the resin. Some heat guns are very powerful and should not be used to move resin around.

Buying a heat gun for resin with a controllable temperature is best, even if you only have high and low options. That way, you can start on the lower temperature setting and see if that works with the resin brand you are using. Heat guns should never be kept on the same spot for more than a few seconds; it should be used in a circular motion over your resin to move it around and eliminate bubbles.

heat gun turning resin yellow

Read our article about choosing the best heat gun for resin

6. Keeping resin products outside may cause yellowing

For those who are pouring a resin table or ornament to keep outside, it might turn yellow within just a few months. The sun can degrade the polymers and cause yellowing. The elements and rain can all contribute to yellowing resin outside.

This is why it is important to know what you are going to be making with your resin so you can buy an appropriate resin with UV protectants in it. There are also proper UV sprays that you can finish your resin art with, and we will cover that in the solutions below.

7. Hardener that is exposed to air will yellow inside the bottle

It happens all the time. You put your resin supplies away and then months later want to make something and notice the hardener has turned yellow in the bottle. This is because the hardener has been exposed to the air and it's starting to oxidize.

You can still use the hardener. When it is mixed with the resin and poured onto a surface or mixed with colorants it will be less yellow looking.

WHAT YOU CAN DO TO HELP PREVENT THE RESIN PIECE FROM LOOKING YELLOW OR TURNING YELLOW

Once the cured resin has turned yellow or starting to yellow on the sides, there is no way to reverse it. The epoxy resin will continue to get even more yellow over time.

1. Only purchase high quality resin

Resin can be expensive but when you purchase resin that is not of good quality, you are pretty much going to get yellowing after even a few months.

If you are using a cheaper brand of resin and want to use colorants to make it a dark color or don't care if it yellows over time, then by all means save the money and go for something less expensive. Otherwise purchase resin from a company that has good reviews about yellowing.

Check Resin Prices And Reviews On Amazon

If you are looking for a high quality multi-purpose resin that has good UV protectant in their formula, we often recommend ArtResin. They make a  good quality resin that is good for coasters, tumblers, jewelry and coating pours.

Check price and sizes of resin in the ArtResin Store on Amazon here

2. Purchase quality colorants that are made for resin

Sometimes it might be as simple as using the right colorants. Powders are generally better than a colorant that has too much liquid in it. Also, it's generally best to use colorants and resin from the same brand.

Chameleon Colors have some of the best color options that are high pigmented and made especially for resin. They offer holographic color and pretty much any color you need. A little goes a very long way.

Check Prices On Amazon

3. Store the unused resin and hardener in a cool, dark place 

Once you have opened the bottles of resin, pour the desired amount of resin and hardener, and then make sure the caps are put tightly back onto the bottle quickly. Get the resin and hardener out of the light and back into a dark place.

4. Pour another layer of colored resin to hide the yellow color 

If you are updating countertops or an art piece that is starting to yellow this is the best way. Or, unfortunately you might just have to live with the yellow color.

why resin is turning yellow

5. For smaller pieces you can try to sand off the yellow color 

Be aware that it might be too late for this. The yellowing might have gone through the whole piece. Examine it carefully to see if it is actually worth it.

6. Keep to darker colors when choosing a color scheme

Darker colors like purples and blacks seem to hold up a lot better than lighter colors. And now that you know the resin could possibly yellow, choose colors that will go with the yellow color. Not ideal, but a good tip to know if you have resin to use up. You might even want to choose a yellow or gold color scheme to start out with.

how to stop resin from turning yellow

7. Use a resin that has a UV stabilizer in it

Do keep in mind that UV stabilizers may keep the resin from turning yellow more slowly. But it will not completely prevent the resin from turning yellow, especially after many years. Every resin will yellow slightly over time, some take longer than others to yellow, some don't yellow as much as others. Look for a resin that already has a UV stabilizer in the formula.

8. Keep a resin yellowing chart 

If you are planning on working with resin over a long period of time or years, then start to keep a chart handy. Whenever you pour the resin, also pour a small sample and keep notes about what you added into it and what type of resin you used. Eventually you will have a good collection of resin pours to go back on to see what's happening and what might be the cause of the yellowing.

9. Seal your resin with a UV spray

You can seal your resin with a UV protectant spray once it has gone through the full cure and is no longer off-gassing.

Here is one many resin artists use:

Kamar UV Spray | Check Price On Amazon HERE

 

MORE RESIN ARTICLES

Resin Table Molds For River Tables

Resin Safety Tools Everyone Must Have

USE RESIN SAFELY

No matter what type of resin you decide to use, always use PPE. Do take time to carefully go over safety data sheets before making anything with resin. And it's very important to follow the instructions on the resin.

Here is the best respirator mask for epoxy resin: this PD-100 Full Face Organic Vapor Respirator by Parcil Safety, who is based in the USA, checks off all of the boxes for resin safety.

best respirator for resin

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