How To Fix Yellowed Resin? 10+ Tested Methods

  • Resin Art 101
  • Posted by: amy-golden
  • Feb 27, 2024

Have you ever been disappointed to find that your once clear and shiny resin has turned a dull and yellow color? It can be disheartening, especially after putting in time and effort to create a stunning piece. So, how to fix yellowed resin? In this article, we'll explore 10+ simple and effective methods to help you fix ugly yellowed resin and restore your artwork to its former glory.

10 + Causes of Resin Yellowing

Resin yellowing can be frustrating, but why does my resin turn yellow? Identifying the root causes can aid in preventing such incidents and how to fix yellowed resin easily. Below are more than 10 common causes of yellow resin: 

Expired Epoxy Resin

Expired epoxy resin can lead to resin yellowing due to improper chemical composition over time (souce: artresin)
Expired epoxy resin can lead to resin yellowing due to improper chemical composition over time (souce: artresin)

The shelf life of different epoxies varies, with their physical properties deteriorating over time. For instance, according to ArtResin's, their products have a shelf life of 12 months if unopened, but this reduces to 6 months once opened. MAS epoxy resins and hardeners last longer with a minimum of one year in sealed containers, extending further when stored in a dry place between 60-90°F. However, an expired resin may appear darker yellow due to natural oxidation but can still be used with dark pigments

Low-quality epoxy resin

Low-quality epoxy resin is one of the causes of resin yellowing due to its inferior chemical composition (source: safetkids)
Low-quality epoxy resin is one of the causes of resin yellowing due to its inferior chemical composition (source: safetkids)

When inferior or impure resin materials are used, they may contain additives or impurities that are more prone to yellowing when exposed to UV light or over time. These additives or impurities can react with the environment and lead to a yellowing effect on the resin. UV light, in particular, may speed up the yellowing process.

Exposure to UV light and sunlight

Uv rays and sunlight can cause the resin to turn yellow and disintegrate over time (source: jdiction)
Uv rays and sunlight can cause the resin to turn yellow and disintegrate over time (source: jdiction)

When the resin is exposed to ultraviolet (UV) light and sunlight, its molecules gradually break down, deteriorate, and undergo a chemical reaction. This can lead to problems such as loss of gloss, delamination, cracking, surface chalking, and yellowing. Prolonged exposure to UV sources, whether natural or artificial, can cause significant damage.

Improper Mixing Ratios or Expired Resin

Improper mixing ratios or expired resin can cause yellowing of the resin, resulting in a discolored final product (source: artresin)
Improper mixing ratios or expired resin can cause yellowing of the resin, resulting in a discolored final product (source: artresin)

When working on a resin project, it's important to pay close attention to the manufacturer's instructions regarding the proper ratios for mixing the resin and hardener. If the ratios are off, the resin may not cure properly, leading to discoloration and even yellowing over time. Additionally, using expired resin can also result in yellowing as the chemical composition may have changed.

Mixing incompatible resin colorants

When incompatible resin colorants are mixed, it can result in the resin becoming yellow (source: amazon)
When incompatible resin colorants are mixed, it can result in the resin becoming yellow (source: amazon)

In some cases, adding colorants that are not compatible with the brand of resin can lead to the yellowing of epoxy resin. Certain colorants may have components that lead to the resin's gradual yellowing. Therefore, when using a specific brand of epoxy resin, it is recommended to use their own powder colorants, as they are specially formulated to work seamlessly with their products.

Keeping cured resin pieces outside

Putting cured resin pieces outside can cause resin yellowing due to exposure to uv rays and environmental factors (source: house grail)
Putting cured resin pieces outside can cause resin yellowing due to exposure to uv rays and environmental factors (source: house grail)

When exposed to sunlight, the polymers in the cured resin break down, resulting in a yellow shade. This degradation can take place within a few months, reducing the visual appeal of resin tables or ornaments.

Therefore, you should consider an appropriate resin with UV light protectants in it if you want to display resin pieces outside. There are also proper UV light protectant sprays that you can finish your resin art with.

Hardener exposed to air 

Chemical reactions can cause resin yellowing when hardener is exposed to air (source: chill epoxy)
Chemical reactions can cause resin yellowing when hardener is exposed to air (source: chill epoxy)

When the hardener is exposed to air, the resin might turn yellow. This comes from a chemical interaction between the hardener and oxygen in the air. Specifically, Yellowing of the hardener in epoxy occurs mainly due to carbonyl formation from thermo-oxidation, where amines in the hardener react with oxygen either during bottling or from oxygen seeping through the plastic container.

Over time, this reaction can cause the resin to yellow and lose clarity. However, you can still use it. Once you mix it with resin or colorants and apply it to a surface, the yellow appearance will fade away.

Using a sealant that yellows

The use of a sealant that yellows is one of the causes of resin yellowing (source: artresin)
The use of a sealant that yellows is one of the causes of resin yellowing (source: artresin)

In some cases, yellowing in resin projects may be caused by the sealant rather than the resin itself. This can result in a discolored appearance. Typically, a sealant is not required before applying resin. 

However, it is advised for paper, loose materials, and natural objects (such as wood) to avoid resin absorption or trapped air bubbles. It's a good idea to test a scrap piece first to see if sealing is required before applying resin.

Using titanium white paint

Using titanium white paint in resin art can cause yellowing of the resin over time (source: blick)
Using titanium white paint in resin art can cause yellowing of the resin over time (source: blick)

Yellowing can happen when Titanium Dioxide, which is present in titanium white paint, combines with any type of epoxy resin. In many cases, Titanium Dioxide acts as a catalyst and can speed up the natural deterioration process when it directly contacts the resin.

To avoid yellowing, it is advisable to apply a sealant to shield the TiO2 from the resin while using titanium white paint beneath it. This protective measure can slow down the discoloration process.

Layering resin coats

The possibility of air entrapment and incorrect curing while layering resin coats might lead to resin yellowing (source: istock)
The possibility of air entrapment and incorrect curing while layering resin coats might lead to resin yellowing (source: istock)

When applying multiple coats of resin, each layer can trap air bubbles or have uneven curing, which leads to discoloration over time. This reaction is more likely to occur when the layers are thick or not allowed sufficient curing time between coats. These imperfections can create a yellowish tint on the resin surface, taking away from its original colors.

Heat and Oxidation

When resin is exposed to excessive heat, such as being placed under direct sunlight or near a heat source, it can cause a chemical reaction that leads to discoloration. The reaction is accelerated by high temperatures, causing resin yellowing over time.

Additionally, prolonged exposure to oxygen can contribute to the yellowing process through oxidation. This means that when resin comes into contact with air for extended periods, it undergoes a chemical change that results in yellowing

High Moisture and Humidity

High moisture and humidity can cause resin yellowing, affecting its appearance and quality (source: meesho)
High moisture and humidity can cause resin yellowing, affecting its appearance and quality (source: meesho)

When resin is exposed to excessive moisture, it can lead to a chemical reaction between the resin and its components that causes it to oxidize and change color. Humidity, especially in hot and humid environments, can accelerate this process. The water molecules in the air can penetrate the surface of the resin, causing it to absorb moisture and become discolored over time.

4 Quick Fixes for Mild Yellowed Resin

Is your once beautiful resin now looking a little yellowed? No problem! We will walk you through 4 fast and simple solutions on how to fix yellowed epoxy. 

Mild Soap and Water Solution 

How to fix yellowed resin with a mild soap and water solution (source: the epoxy resin store) 
How to fix yellowed resin with a mild soap and water solution (source: the epoxy resin store)

Wondering how to fix yellowed resin and bring back the freshness to your yellowed resin? Try a gentle cleaning with a mild soap and water solution – it's a quick and easy fix!

Step 1. Mix a mild soap, such as dish soap or gentle hand soap, with warm water in a bowl. Use a modest amount of soap to prevent excessive sudsing.

Step 2. Apply the soap and water solution on a gentle cloth or sponge. Gently scrub the yellowed resin surface with the cloth, applying light pressure.  

Step 3. Rinse the cloth or sponge with clean water and pat dry to prevent water spots.

Step 4. Use another dry, clean cloth to gently pat-dry the resin. Be sure to eliminate all moisture to avoid water spots or additional staining.

*Note: Remember you should not use harsh chemicals as this could cause more harm to the resin.

The method is suitable for individuals looking for a cost-effective solution that can be easily done at home. It only takes a short amount of time to apply and can brighten the resin back to its original state. 

Isopropyl alcohol for residue removal

Isopropyl alcohol is effective for how to fix yellowed epoxy due to its strong solvent properties (source: pbuy sites)
Isopropyl alcohol is effective for how to fix yellowed epoxy due to its strong solvent properties (source: pbuy sites)

Following these steps using Isopropyl alcohol can help effectively remove residue and fix mild yellowing on resin items:

Step 1. Start by preparing a clean work area and gather all the necessary supplies, including isopropyl alcohol, cotton pads or swabs, and a soft cloth.

Step 2. Carefully pour a small amount of isopropyl alcohol onto a cotton pad or swab.

Step 3. Gently rub the yellowed resin with the isopropyl alcohol-soaked cotton pad or swab in a circular motion.

Step 4. Once the residue is removed, use a clean cotton pad or swab soaked in isopropyl alcohol to clean any remaining residue or marks. After the resin is clean, dry and polish the surface with a gentle cloth.

*Note: 

  • Work in good ventilation and away from open flames because Isopropyl alcohol is highly flammable
  • Put on gloves to protect your hands from the drying effects of isopropyl alcohol
  • Avoid using isopropyl alcohol on painted or sensitive surfaces as it can damage them

The effectiveness of this method will vary depending on the specific resin and the extent of yellowing, but in mild cases, it can provide fast results within a few minutes to an hour.

Application of Resin Sealants for Restoration

How to fix yellowed resin with resin sealants (source: indiamart)
How to fix yellowed resin with resin sealants (source: indiamart)

How to fix yellowed resin? Check out this super cool method using resin sealants for restoration:

Step 1. Gather the necessary supplies, including a resin sealant, a clean cloth, and a soft brush or sponge.

Step 2. Use a cloth or soft brush to gently clean the surface of the yellowed resin, removing any dirt or debris.

Step 3. Shake the resin sealant well to ensure appropriate mixing. Next, use a brush or sponge to apply a thin, even layer of sealer using a brush to the yellowed resin. 

Step 4. Allow the sealant to dry according to the directions on the sealant's container. If necessary, repeat the process for stubborn yellowing.

*Note: 

  • To verify compatibility and prevent damage, test the resin sealant on a small, inconspicuous area before applying it to the entire surface
  • Keep the resin object away from moisture or high humidity while the sealant is drying to prevent streaks or uneven drying
  • Opt for one that dries transparent to maintain the artwork's original look
  • For delicate pieces, consider using a spray sealant instead of brushing to prevent damage
  • Ensure the sealant is compatible with your specific artwork; for instance, a sealant for acrylic paintings may not be suitable for photographs
  • Look for sealants labeled "non-yellowing," like Krylon Crystal Clear, Matte, Golden Archival Spray Varnish, or UV Resistant sprays

The speed of the restoration process will depend on the drying time required by the resin sealant, which can range from a few hours to overnight. The overall effectiveness and longevity of the restoration will depend on the quality of the resin sealant and the maintenance of the treated surface.

Consideration for UV Protection

How to fix yellowed resin with uv protection to combat mild yellowing in resin (source: totalboat)
How to fix yellowed resin with uv protection to combat mild yellowing in resin (source: totalboat)

If you notice that your resin item is starting to yellow, it might be because of exposure to UV light. One way to prevent further yellowing is by moving the item to a shaded area or indoors where it won't be directly exposed to sunlight. 

Another option is to apply a UV-resistant clear coating or sealant which can provide additional protection against sun damage.

*Note: When considering UV protection for how to fix yellowed resin, it is vital to use a high-quality UV-resistant clear coating or sealant. The duration of the coating to effectively prevent yellowing depends on the specific product and the exposure to UV light.

Deep Cleaning and Restoration Methods for Heavily Yellowed Resins

If you have resin objects that have become heavily yellowed over time, how to fix yellowed resin? With proper care and procedures, you may restore your favorite objects to their previous brightness.

Step 1: Sanding Process for Yellowed Resin

The sanding process for yellowed resin involves removing the outer layer to reveal a fresh, clear surface (source: autodest instructables) 
The sanding process for yellowed resin involves removing the outer layer to reveal a fresh, clear surface (source: autodest instructables)

To sand yellowed resin, first, identify the areas on the resin surface that have become yellowed. These areas typically stand out from the rest of the resin and may appear discolored or faded. Then, grab a fine-grit sandpaper, ideally around 400 to 600 grit, and begin gently sanding the affected areas. Remember to use a circular motion and apply even pressure to ensure a consistent sanding process. You can read our article about sanding epoxy resin to make your working process easier!

*Note: Avoid pressing too hard as this can create unwanted scratches on the resin surface.

Step 2: Buffing to Restore Shine

Buffing to restore shine for yellowed resin can bring back the original luster (source: glasscast)
Buffing to restore shine for yellowed resin can bring back the original luster (source: glasscast)

After completing the initial sanding, it is recommended to switch to a higher-grit sandpaper, such as 800 to 1000 grit, for a finer finish. Next, apply a resin-compatible polishing compound to the surface. This compound will help to remove any remaining yellowing resin. To buff the surface, use a buffing pad or a soft, lint-free cloth and make circular motions to evenly distribute the polishing compound.

Step 3: Repeated Sanding and Buffing (if necessary)

Repeated sanding and buffing is necessary to achieve a smooth and flawless surface (source: epoxio)
Repeated sanding and buffing is necessary to achieve a smooth and flawless surface (source: epoxio)

To achieve optimal clarity and shine, if yellowing persists after the initial sanding and buffing process, it is recommended to repeat the steps with even finer grit sandpaper ranging from 1200 to 1500 grit. Next, you continuously should keep buffing the surface until the desired level of clarity and shine is achieved.

Step 4: Final Polishing Step

The polishing step on resin artworks enhances their shine and brings out their vibrant colors (source: acrylgiessen)
The polishing step on resin artworks enhances their shine and brings out their vibrant colors (source: acrylgiessen)

Polishing is an optional step on how to fix yellowed resin. However, if you want to continue applying a resin-specific final polish to enhance the luster of the restored resin, you can do the following steps:

First, begin by cleaning the surface of the heavily yellowed resin with a mild detergent or soap and warm water. Next, use a resin-safe abrasive compound or polish to remove the yellowed layer and restore the resin's original color and shine. This may involve manual scrubbing or the use of a polishing tool, depending on the extent of yellowing and the size of the surface area. Finally, apply a resin-specific final polish to further enhance the shine of the restored resin. For more instructions on how to polish epoxy resin in detail, refer to our guidelines for best results.

Step 5: Cleaning Resin Dust

Cleaning resin dust after sanding and buffing the resin's surface is crucial for a smooth and polished finish (source: freepik)
Cleaning resin dust after sanding and buffing the resin's surface is crucial for a smooth and polished finish (source: freepik)

Thoroughly clean the surface of the resin to ensure that all dust or particles are removed. This step is vital for preparing resin for the following stage of restoration.

To clean resin dust, start by using a soft, damp cloth or a gentle cleaning solution made for the resin to wipe down the surface carefully and ensure to cover the entire area with even motions. After each wipe, rinse the cloth or sponge frequently with clean water to prevent dirt transfer. Finally, let the resin air dry completely after wiping, avoiding using heat or a hairdryer as extreme temperatures can cause damage to the resin.

*Note: Avoid using harsh chemicals or abrasive cleaning products as they might harm or discolor the resin.

Step 6: Protective Coating (Optional)

Using a protective coating on resin item surfaces can help to prevent scratches and damage (source: forest 2 home)
Using a protective coating on resin item surfaces can help to prevent scratches and damage (source: forest 2 home)

After selecting a suitable protective coating product, select a suitable protective coating product such as a clear resin or resin sealant as a protective coating to prevent future yellowing. Then, apply a thin and even layer of the protective coating onto the surface of the resin, ensuring full coverage. Lastly, allow resin to dry thoroughly based on the manufacturer's recommendations.

The working time of this method will vary depending on factors such as the size and complexity of the resin item, the extent of yellowing, and the individual's level of experience with the restoration process. It may require several hours or even days to complete the entire cleaning and restoration process, including drying and curing time for the protective coating.

How to Prevent Resin from Yellowing?

Do you love working with resin but hate the yellowing that occurs over time? We've got some tips and tricks on how to stop resin from yellowing, so you can enjoy your projects for longer!

Proper Resin Storage

After each usage, cover the lid immediately to keep oxygen from running into the hardener (source: artresin)
After each usage, cover the lid immediately to keep oxygen from running into the hardener (source: artresin)

It is best not to open the bottle of resin until you are completely ready to use it for your projects. If you do not want to start your resin projects right away after getting your online buy, do not open it early. Keeping the lid tight reduces oxygen exposure to the resin, preserving its durability and efficiency.

After each usage, cover the lid immediately to prevent oxygen from running into the hardener. Additionally, before utilizing the resin, always remember to verify the expiration date to ensure its effectiveness.

UV Protection for Cured Resin Items

Uv protection for cured resin items is essential to prevent yellowing, fading, and deterioration over time (source: the epoxy resin store) 
Uv protection for cured resin items is essential to prevent yellowing, fading, and deterioration over time (source: the epoxy resin store)

You can use a UV protectant spray to seal your resin once it has fully cured and stopped off-gassing. These sprays are compatible with different types of resin including synthetic resin, UV resin, polyester resin, and epoxy. Apply a thin layer of spray on the dry resin to ensure proper curing and avoid spraying it on liquid resin.

Keep a Resin Yellowing Chart

Keeping a resin yellowing chart helps to track and understand the changes in resin color over time (source: resin geodes)
Keeping a resin yellowing chart helps to track and understand the changes in resin color over time (source: resin geodes)

If you work with resin for an extended period, keeping a chart is recommended. Alongside each resin pour, take note of the date and keep a small sample. This collection will help identify the cause of yellowing or color changes. Monitor new products' yellowing process and compare samples exposed to different environments, including UV light.

Using Darker and Cooler Colors

Use darker and cooler colors to reduce resin yellowing over time (source: art in context)
Use darker and cooler colors to reduce resin yellowing over time (source: art in context)

Darker shades such as purples and blacks tend to withstand fading better compared to lighter colors. Resin can potentially yellow over time, so selecting colors that complement this yellowing effect can be a practical choice. This advice is useful for utilizing leftover resin. In fact, consider starting with a yellow or gold color palette for your project.

Choosing High-Quality Resin

Choosing high-quality resin is crucial in preventing resin from yellowing and maintaining its original appearance (source: youtube) 
Choosing high-quality resin is crucial in preventing resin from yellowing and maintaining its original appearance (source: youtube)

You should choose high-quality plastic with the ability to retain its original color without yellowing. Reputable companies often invest more in their formulas by incorporating UV stabilizers and HALS, which provide additional protection against discoloration. 

We have compiled a list of 10+ best epoxy resins with a thorough analysis of the outstanding features and advantages and disadvantages of each type.

Applying Protective Coatings

One of the best ways to prevent resin from yellowing is by applying protective coatings (source: wood magazine)
One of the best ways to prevent resin from yellowing is by applying protective coatings (source: wood magazine)

Protective coatings are considered as one of the most essential stages in "how to stop resin from yellowing." They act as a barrier against UV rays and other external factors that result in discolouration. Some commonly used protective coatings include epoxy resin coatings, polyurethane coatings, and UV-resistant clear coatings.

Considering Indoor Display Options

Choosing an indoor display is one of the best ways to prevent resin from yellowing (source: ultra clear epoxy)
Choosing an indoor display is one of the best ways to prevent resin from yellowing (source: ultra clear epoxy)

Some of the best places to display your resin artwork are areas with minimal exposure to direct sunlight and stable temperatures, like living rooms or bedrooms, avoiding moisture-prone spaces such as bathrooms or kitchens. 

Investing in UV-Blocking Display Cases

Buying in uv-blocking display cases is critical to keep the resin from yellowing over time (source: pinterest)
Buying in uv-blocking display cases is critical to keep the resin from yellowing over time (source: pinterest)

UV exposure can discolor and ruin resin artwork. Therefore, you can use UV-blocking display cases including acrylic cases with UV-resistant coatings and glass cases with UV-protective films. These cases provide a protective barrier against harmful UV rays, preserving the vibrant colors and overall quality of resin art pieces.

Choose Appropriate Types Of Resin

Choosing the right types of resin is crucial in preventing resin from yellowing and maintaining its quality (source: art tree creations)
Choosing the right types of resin is crucial in preventing resin from yellowing and maintaining its quality (source: art tree creations)

Choosing different types of resin appropriately is essential for non-yellowing UV resin. Resin yellowing occurs due to factors like UV exposure, temperature, and the quality of the resin. According to ATLAS, a third-party epoxy resin yellowing tester, they tested many different types of epoxy under the same UV exposure conditions. 

After 8 weeks of monitoring, they discovered the top 6 types of epoxy with the least yellowing. They are ArtResin, ThickCast Casting Resin, Entropy Resins Super Sap CCR, Resin Obsession Super Clear Resin, EX-74, and West Systems 207 Special Clear. By selecting UV-stable resins, using additives like UV inhibitors, and maintaining proper curing conditions, we can effectively prevent resin yellowing.

Conclusion

In conclusion, how to fix yellowed resin? Fixing yellowed resin is easier than you might think. By understanding what causes the yellowing, following the steps we've provided, taking preventative measures, and helpful tips, you can keep your resin looking clear and vibrant. 

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I work as a freelance blogger in Seattle, Washington. I've been freelancing full-time for 5 years. I'm interested in anime, resin art, and mechanical keyboards.

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