How long does epoxy resin last once opened?

How long does epoxy resin last once opened? For most of us, the resins are used once they are opened and the time frame that we need to keep them depends on how we use them.

If you have just a small project to work on, the resin can last for years even after it is opened.

How do you know if epoxy is expired?

Does epoxy have an expiration date?

Epoxy systems will not go off in a week or two once the tin has been opened, but they can lose their effectiveness over time.

The exact timescale depends on many factors, and there is no hard and fast rule as to when they are too old to use.

It is also very difficult to tell when epoxy has gone off by sight or smell alone.

Does resin expire?

If the epoxy resin is stored correctly, meaning it is tightly sealed and in a cool, dry place with no light exposure then yes it will last for many years.

If you are using a two-part epoxy resin kit then once one of the bottles has been opened you should use up the rest of the bottles within 1-2 years as there could be a small change in how effective it will be after this time, if stored correctly.

How long can you keep mixed epoxy resin?

However, the material will gel if you keep it in a bowl at room temperature for more than approximately 20 minutes. This means that after mixing the epoxy resin, you should apply it quickly.

If you want to be on the safe side, mix a little less epoxy resin than is recommended, and then mix more as needed.

Be aware of cold temperatures! When mixed with hardener, the material will not cure properly if the temperature drops below 10 degrees Celsius (50 degrees Fahrenheit).

The same thing can happen when you expose mixed epoxy resin to cold air currents.

In addition, we recommend against cooling mixed epoxy. Why? Because cooling can cause condensation on the inside of the container or mixing cup which could lead to bubbles forming in your workpiece.

Does resin yellow over time?

The answer is yes, resin will yellow over time. All epoxy resin has a shelf life, but with proper care and storage, you can extend that shelf life to about 1-2 years.

Alas, there’s no way to prevent the resin from yellowing at all if you plan on opening it. The yellowing is caused by a reaction between the epoxy and UV light (natural or artificial).

Resin’s color is not going to turn from clear to gold overnight, but over time it will gradually change from clear to a straw or honey color.

In extreme cases, if left out for long periods of time or exposed to direct sunlight for some duration, the resin may become brown in color. Don’t worry! You can still use the resin once UV yellowing occurs—it just might affect your project’s results!

To minimize the risk of this happening when working with our Art Resin brand specifically we recommend purchasing our ArtResin Epoxy Resin Color Kit which contains 3 pigment colors: Titanium white, Carbon black, and Transparent amber (which can help counteract any natural slight yellowing that does occur).

Can you use resin if it turns yellow?

If your resin has turned yellow, you should not use it.

Yellowing is a sign that the resin has expired and will not cure properly.

If you do use the resin after it has turned yellow, it may still look clear when you pour it, but it won’t cure as intended. You need to discard the resin if it turns yellow.

However, if you only notice yellowing on the surface of your resin mixture or if your mix was left exposed to air for a few minutes and turned slightly yellow, then you can salvage the batch by mixing in new, fresh resin and hardener.

The new components will help counteract the discoloration caused by age or exposure to oxygen and heat.

Does unopened resin go bad?

There are a few factors that can lead to bad resin, and luckily none of them involve time alone.

The main things to consider when you’re wondering if your unopened bottles of resin have gone bad are heat, cold, light, and moisture.

If your unopened resin has been exposed to extreme heat or cold (think: temperatures outside the recommended range that is usually between 68-77 degrees Fahrenheit), it can affect the chemicals in the resin which could result in poor curing.

If they’ve been exposed to excessive light (like leaving them out on a countertop or windowsill) they could potentially begin to cure before you’re ready to start pouring.

And finally, if you leave them somewhere where there’s significant moisture (like a bathroom), it could introduce water into the mix which will prevent proper curing.

How do you store 2 part epoxy?

Once you’ve opened your resin container, you’ll want to store it in a cool, dry place.

Since epoxy is an adhesive, it should be stored in an airtight container.

This can be a resealable plastic bag or something similar as long as the container is large enough that there is no risk of spilling the resin.

You will also want to keep the resin out of direct sunlight and out of reach of children and pets.

Once you have finished using the resin for your project and closed the container, it can be stored for up to two years if kept in a cool, dry place.


In summary, epoxy resin used for craft and hobby projects should be stored in airtight containers in a dark place at room temperature.

Temperatures over 120°F can cause the resin to prematurely cure. Many of these resins come in two bottles, one with the resin and one with the hardener.

It is important that you mix these before you use them or else you will end up with a sticky mess on your hands.

It doesn’t matter if the epoxy resin is opened or not as long as it is stored properly and above 70°F it will last for years before it fully cures into a solid form.

This means you do not have to worry about using all of your store-bought epoxy resin at once and can save some for other projects later on down the road!

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Martin Flood

Martin Flood has been working in the construction industry for over 20 years as a general contractor with expertise in remodeling projects that are large or small. He has furthered his career by specializing in epoxy resin flooring, providing excellent service to both commercial and residential clients. Martin’s experience enables him to offer professional advice on how to choose the right type of project based on your needs and budget.

1 thought on “How long does epoxy resin last once opened?”

  1. Hi, Martin, we were thinking about using translucent grout for glass tiles as a backsplash for two bathroom vanities in separate bathrooms not being remodeled simultaneously. According to the manufacturer once the container is opened we cannot save the unused portion for the second bathroom vanity. Is translucent grout different from the epoxy resin covered by your post?


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