This is probably the most common reason behind why most epoxy turn yellow. UV rays excite the molecules in the polymer and decompose it to produce quinone, a chromogenic group. This is the reason for the yellowing of the resin process.

Since UV rays also exist in natural light, natural light (sunlight) is the most likely source from which your resin craft can be exposed to UV light. And while it often takes some time for this yellowing to occur, it is often unavoidable when exposure is prolonged.

To prevent this from happening, you will find that epoxy resin has been shown to continue yellowing even if it is placed somewhere with no further exposure to light at all. What we can do is to place the resin artwork as far away from natural light as possible to delay its yellowing, and the use of color pigments can also play a role. Although this doesn’t really stop the yellowing, it does mask the disfigurement, giving your resin art a more homogeneous coloring which makes the craft more pleasing to the eye.

2. Exposure To High Temperatures

The cured epoxy resin has a high temperature resistance for instant contact. As you know, epoxy resins such as ashtrays and coasters have good performance. However, the epoxy resin works will also turn yellow under excessive high temperature and heat source environment for a long time.

The cured epoxy resin has a high temperature resistance for instant contact. As you know, epoxy resins such as ashtrays and coasters have good performance. However, the epoxy resin works will also turn yellow under excessive high temperature and heat source environment for a long time.

2.1 High environment temperature of storage

Please kindly check if your resin art storing the below place, and get your resin craft away from them:

1. A space that isn't climate controlled, such as outdoors or in an attic.
2. Above the vent
3. A warm spot such as a conservatory or in a sunny window
4. Under light sources that generate heat, such as gallery lights.

2.2 Over torching:

This happens when you use a flame torch on your freshly crafted resin for too long or bring the torch too close to it, you will find  your resined piece has only yellowed in certain spots and not throughout. To prevent this from happening, always exercise caution when using a flame torch and keep the touch moving back and forth although the torching process. Also, never hold the torch too close to the resin.

2. Exposure To Water

In the case that none of the issues mentioned store in a high temperature above is a problem with your resin and you are still noticing your resin turning yellow.  More often than not,then chances are your resin has exposed water .   Thankfully, fixing this is rather easy: just follow the instruction “store in a cool dry place”.

3. Pigment Things:

4.1 Paint not dry

Sometimes, we often add painting art to resin art. It is inevitable that we will use a variety of pigments. If the resin is applied to the paint that is not completely dried, the color may change. Even if the paint looks dry to the touch, be aware that the surface is dry and the paint in the center may still evaporate. If it comes in contact with the resin before the resin is fully dried, the result may be turbidity curing or eventually discoloration/yellowing. The best practice is to allow enough time for the paint to dry completely before resinizing.

4.2 Using Titanium White

In order to make a more perfect resin art, it is inevitable that titanium white paint is sometimes used, the titanium dioxide in it and any brand of epoxy resin will interact, and this may cause the resin craft to turn yellow. The best practice when using titanium white paint under resin is to apply an appropriate sealant to act as a barrier between the Ti02 and the resin.

Why Epoxy Hardener Turned Yellow In The Bottle?

In addition to finding that your resin art can change color, you may also find that your epoxy hardener also develop a yellow color over time even when stored properly. This is because, over time, natural oxidation gradually occurs, is not caused by UV light.

Can I Still Use an Epoxy Resin Hardener That’s Turned Yellow?

It usually depends on the degree of yellowing to determine whether it can continue to be used. If the degree of yellowing is slight, you dilute the hardener by adding the resin to it, which makes any discoloration hardly (if at all) noticeable. If the yellowing is pronounced though, it’s best you simply replace the hardener.

A good way to prevent your resin hardener from yellowing quickly is to purchase smaller resin kits.  It would get used up more quickly than a big bottle before yellowing sets in.

How Do You Fix Yellowing Resin Craft?

Unfortunately, once the resin turns yellow, there is nothing to reverse it. Though fixing yellowed epoxy resin is not an easy affair, it is not impossible either. You can try to sand the yellowed resin and apply a new coat, but you need to be careful not to ruin the entire epoxy resin art work.

More Important: Choose A Yellowing-Anti Epoxy Resin

In addition to the above-mentioned measures taken after the resin work is completed, do we have a solution to the root cause? Yes, choose an Anti-Yellowing Epoxy Resin. There are some resins on the market that contain HALS ((hindered amine light stabilizer) and UV stabilizers, designed to reduce the yellowing. Unlike regular resins, these anti-yellowing epoxy resins would not turn yellow as fast.

What needs to be mentioned here is JDiction 3X UV PROTECTION FORMULA, in addition to Supperior HALS and UV stabilizer, this product also realizes the removal of the quinone, a chromogenic group that will turn yellow when exposed to ultraviolet light via innovative formula. This non-toxic, odorless epoxy resin provides the same quality as JDiction’s classic formulas with the extra benefit of an advanced UV protection. Test confirmed, this special formula resin has 3 times the UV resistance of other brands in the same environment.

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