Hot glue is a very versatile glue, that can be used for many different projects and with a wide variety of materials. But how long will hot glue last?
Industrial hot glue only lasts one year unopened and about six months once opened. Regular hot glue will last between two and six years unopened and between 6 months and three years once opened. It depends on the amount of resin and antioxidants inside the hot glue sticks.
Once a package of hot glue sticks is opened the glue sticks will start to yellow slowly over time. And after some time the resin within the glue sticks will no longer react well when applied.
This will result in a loss of adhesion strength over enough time.
The Resin Contained in the Hot Glue Sticks Determine the Shelf Live
Hot glue sticks are made out of a base material and several additives.
The most frequently used base materials include EVA (Ethylene-vinyl acetate) for most regular hot glue sticks. PO (Polyolefins)for industrial-grade hot glue sticks, PA (polyamides) and Polyester are both also used for industrial-grade hot glues.
There are other base materials that are less frequently used like TPU, PUR, SBC, and more. You can read all about the additives and base materials of hot glue sticks right here on Wikipedia.
Additives of hot glue sticks include tackifying resins, waxes, plasticizers, antioxidants, UV stabilizers, pigments, biocides, flame retardants, antistatic agents, and fillers.
The tackifying resins are the main reason why hot glue sticks become unusable after a while.
High-temperature hot sticks that are often used in industrial applications tend to have a higher amount of tackifying resins. That’s also why they tend to have a shorter shelf life.
Once the Hot glue sticks have contact with air oxidization will start reducing the shelf life. This will yellow the hot glue sticks over time, eventually making them brittle.
Antioxidants are added to reduce the oxidization effect and keep them from oxidizing too quickly.
How to Store Hot Glue Sticks Properly?
Storing the hot glue sticks properly will extend their shelf life quite drastically.
Hot glue sticks should be stored in an air-tight container in a place where they are not exposed to any sunlight. The air-tight container will slow down the oxidization process and keeping the glue sticks away from any UV light will ensure that the resin contained within them doesn´t yellow over time.
You can use regular Tupperware as a storage container. But there are also air-tight containers like this on Amazon.
The air-tight container will keep the resin from oxidizing too fast.
It is best to store the hot glue sticks inside a drawer or something similar where they are protected against direct and indirect UV light.
The resin contained inside the hot glue sticks will react to UV light and start to yellow after a while. Eventually, the bonding strength of the hot glue sticks will degrade as the resin becomes brittle.
Does Hot Glue Expire?
Hot glue will expire after a while as the resin contained inside becomes brittle as it oxidizes or reacts with UV light. The shelf life is dependent on the additives and the amount of tackifying resins inside the glue sticks. Hobby hot glue sticks will generally last longer than high-temperature industrial hot glue sticks.
I personally have hot glue sticks that are about three years old now and while have started to yellow slightly they still work quite well and adhere well.
But those are “hobby” hot glue sticks that don´t contain a lot of resin.
Industrial hot glue sticks, which need to be applied at higher temperatures and often require a special hot glue gun, will expire much faster.
Does Hot Glue Break Down?
Hot glue is essentially a type of plastic that is mixed with tackifying resins and some other additives to make it possible to melt them.
Hot glue does not break down easily on its own. It can take 10 or even 50 years for hot glue to break down. Hot glue sticks are often made out f EVA, PO, or PA. All of these plastics take a very long time to break down and some, like Polyolefins, can take 100 years or more to break down.
EVA (Ethylene-vinyl acetate) is the most often used type of plastic for hot glue sticks. You might know EVA-Foam from building costumes.
EVA is often used for regular hot glue sticks that are sold in craft stores. These hot glue sticks have a low melting point and adhere quite well to all kinds of materials.
EVA will last anywhere from 10 to 50 years depending on the surrounding temperature and if it is exposed to the elements.
PO (Polyolefins), PA (polyamides), and Polyester are all types of plastics that are used for more specialized hot glue sticks.
They all require either a low temperature to melt or a very high temperature.
All of these plastics will take a very long time to decompose. PA and Polyester will take anywhere from 20 to 200 years to compose.
And PO can take anywhere from 20 to 100 years to break down.