Shelf Life & Yellowing in the Bottle

Updated: Nov 11, 2021

Epoxy Resin is ideally best used within 6 months of purchase. Try not to purchase more then you will use up.

Shelf Life/Storage: Store product in a dark but well ventilated area that is above 10C. If product happens to freeze, let it thaw completely, and return to room temperature (there is a blog on our website about how to best do this).

ArtWorks Resin Resin, Liquid Diamonds Casting Resin, PuDuo Resin and all iCoat Epoxies have a shelf life of 12 months unopened, and 6 months once opened (ensure lids are replaced tightly). The reason is due to oxidization. When the hardener in any resin is exposed to oxygen, it has a yellowing effect. This does not mean it won't cure. Even once past shelf life, the product still works, and will still cure. But older product may produce more bubbles that are more difficult to eliminate. You may want to just use it up only with darker colours or tinted over wood. All our epoxy resin products have UV additives. Optimally, try to plan to purchase only as much resin as can be used in a 3 month period if possible.

If you tend to make smaller items, like jewellry, purchase the smaller kit sizes. As tempting as it is to take advantage of the lower per oz prices in larger containers, it's not helpful, if it's sitting on the shelf, and no longer fresh by the time a person goes to use it.

Always wipe around the bottle opening of the hardener (especially Liquid Diamonds ), when done so that a powdery substance does not form and drop particles into the bottle when opened again.

Please keep containers tightly sealed when not in use. The hardener (part B of Liquid Diamonds ) is extremely sensitive to moisture. DO NOT allow hardeners to remain open or have lid loose when not in use.

Please note that bottles are filled by weight, not volume and will not be filled right to the top.

Yellowing in the bottle: Yellowing in the bottle occurs in most if not all resins, and it is from oxidization, (from exposure to oxygen not from exposure to uv light). It's very exaggerated & much more noticeable in the larger sized containers. Some resin companies use white containers so you don't see (or notice) the yellowing as much as you do with clear containers. Once mixed, the epoxy will be clearer and less yellow (if it's within the year shelf life).

Yellowing of hardener in the bottle can happen for numerous reasons. It can be from UV inhibitors that are an added ingredient, as they are actually yellow in colour. Yellowing of hardener also is caused by oxidation which happens to every brand. All our brands we carry, have the common shelf life, which is 6 months opened, and 12 months unopened. People can & do use epoxy past its shelf life, however if using older resin, try to use coloured and darker tints (rather then whites or clear). When mixed, a yellowed hardener may go clear or pretty close to it if within the year shelf life. It will appear less yellow once on a piece due to the fact it is mixed with the other part (A) resin, which dilutes it, and once spread out it's less observable to the eye. One trick many long time resin users do with yellowed hardener, is some people add a tiny drop of blue or violet tint to the mixed epoxy to trick the eye from seeing the yellow. This trick, allows people to use up resin that is no longer new, and in it's ideal time frame.

If the product has gone into the deeper darker amber tones, then it's well past it's shelf life, or it's been exposed to more oxygen then it should be, or there may be some type of contaminant in it.

You will also notice a difference in smell of aged (yellow) hardener. It will often have quite a bit stronger odour than when it's brand new, again due to oxidization process.

Many people still use their aged ambered hardener, and find it can still work on base coats, or wood or other projects where colour is not important, but we do not recommend using to topcoat anything where colour is important. You may also find aged resin products have a shorter pot life, and you may need to apply it much quicker once two parts have been mixed.

If an unopened hardener has gone slightly yellow before the one year mark, it could be from the plastic (HDPE) bottles, since they do breath a little allowing some oxidation to still occur. This is why epoxy resins have a shelf life. Ideally, we recommend not buying more then you will fully use up within 6 months of purchase. Although it's tempting to take advantage of volume pricing, it may not be worthwhile if product is not going to be used up within 6 months, dependant on types of projects you are working with.

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