Adhesive, also called glue, or paste, is any nonmetallic material that is applied to a single or multiple surfaces of two separate items in order to bind them together and prevent them from being separated by forces applied on them.
When compared to conventional binding procedures like sewing, mechanical fastening, or welding, the utilization of adhesives has a number of distinct advantages.
These advantages include the capacity to bond multiple materials together, better distribution of binding force across a joint, cost-effectiveness since the process can be easily mechanized, and greater flexibility when dealing with complex design and construction.
So, you suddenly need to stick something together and you remember that you kept your glue somewhere in a drawer or toolbox.
You dash for it and there it is lying dusty. You wonder whether it has expired or not. Will it work?
These are the questions I’m going to address in this article.
But to understand it better, let’s consider different types of glue.
Types of Glue
- These are glues that harden the surface to be attached by drying.
- These are adhesive that will require you to apply light pressure for them to stick the adherends together.
- These are adhesives needed to create strong attachments that can resist shear and tear, for instance, gluing a wooden counter.
- Hot adhesives are those that exist as thermoplastics applied in their molten state at high temperature. They solidify on cooling.
- These are glues that stick items, particularly metal when in contact in the absence of oxygen.
- Multi-part glues creating sticking together by mixing several components which can undergo chemical reaction making polymers to cross-link. E.g. polyester resin – polyurethane resin.
- This is a type of adhesive that enable hardening through a chemical reaction that requires an external energy source such as heat.
- These are glues that originate from organic sources such as natural resins, animal proteins, vegetables, etc. They are called bioadhesives.
- Synthetic adhesives are derived from hydrocarbons such as thermoplastics, elastomers, and emulsions. Some examples include epoxy and cyanoacrylate.
Shelf life of Glues
Different glues and adhesives have varied shelf lives, with some lasting longer than others. Heat, oxygen, water vapor, freezing, and other environmental factors can damage the adhesive over time, inhibiting it from performing its intended function.
The shelf life of glues will depend on its components.
Different components such as primary resins, plasticizers, thickeners, film corners, fillers, solvers, antifungal agents, wetting agents, emulsifiers, and antioxidants make up part of the regular adhesive formulations available in stores.
|Type of Glue||Product Examples||Typical Shelf Life|
|PVA Glue||Elmer’s School Glue|
Titebond Wood Glue
Aleene’s Fabric Glue
|2-3 Years (sealed)|
6 – 12 months (opened)
Gorilla Super Glue Gel
|1 Year (sealed)|
0 – 2 months (opened)
|Polyurethane||Gorilla Glue Original|
Titebond Liquid Glue
|1-2 Years (sealed)|
12 months (opened)
Does Glue Expire?
Yes, glue expires, usually with a shelf life of about 1-2 years before going bad. Different glue have different chemical components. That makes the expiration dates for glue vary from 6 months when opened to 3 years when sealed.
Most types of glues are marketed to have a two-year shelf life, but in practice, based on the type and how it has been stored, it may be completely safe to use after that time.
According to industry standards, the normal shelf life of most wet craft items (such as liquid glue, spray adhesives, paper-backed adhesives, paint, and markers) is one to two years after they are first opened.
What Makes Glue Go Bad/Expire?
However, even though glue has a very long shelf life, at some point it will begin to degrade, although the particular mechanism by which this occurs may vary depending on the type of adhesive used.
Emulsion Plastic-vinyl acetate (PVA) adhesives such as school glue and wood glue begin to degrade after a year or two when the solvent (typically water) begins to separate from the adhesive (PVA).
The adhesive clumps together, generating a hard plastic-like substance that renders the glue ineffective.
Superglue and polyurethane glues (such as Gorilla Glue) are prone to exploding when exposed to moisture.
In comparison to regular glue, superglue has a far higher reactivity, reacting even with the smallest quantity of moisture found in the air.
Similar to the expiration date for most natural products, glues have a shelf life.
Particularly with natural glues and liquid water-based glues, you will find that once they have reached their expiration date, they may become moldy and useless, if not completely ruined.
How do you know if glue is expired?
How do you determine the expiration date of your glue? Household glues often have a lengthy shelf life of several years, and manufacturers may choose not to include an expiration date on the container. On the other hand, most packaging will have a “production date” printed on it, which indicates when the adhesive was created.
Household glues often have a lengthy shelf life of several years, and manufacturers may choose not to include an expiration date on the container in some cases.
On the other hand, most packaging will have a “production date” printed on it, which indicates when the adhesive was created.
A large string of characters and figures is sometimes substituted for the readable format in which this is printed on occasion. Unfortunately, there is no standard format for the codes, therefore they are referred to as “coded dates.”
The manufacturers’ websites will provide instructions on how to decode any coded dates you may come upon.
Using the above example, the first letter may represent the month in which the glue was manufactured, and the second number could represent the year.
It’s not very useful if you have a bottle of old glue and want to know if it’s still good, but for the vast majority of glues, you will definitely tell if it’s still good or not just by glancing at the bottle.
This page’s table provides an overview of glue kinds and the normal shelf lives for each type of adhesive.
This page’s table provides an overview of glue kinds and the normal shelf lives for each type of adhesive. How to Store Glue
Despite the fact that different glue kinds have distinctly different chemical compositions, there are a few general guidelines you may follow to extend the shelf life of any type of glue within your household.
How to Store Glue
- Don’t open your glue container until you’re ready to use it.
- Reactive glues, such as Superglue, are a good example.
- When glue is sealed, it lasts significantly longer than when it is not.
- Keep glue away from moist areas and high humidity when storing.
- When exposed to moisture, polyurethane and cyanoacrylate glues react.
- Even a small amount of moisture in the air is sufficient to induce CA glue to harden.
- Keep the container away from any heat sources.
- When subjected to heat, some thermoplastics have a direct reaction.
- Other polymers respond more quickly when exposed to greater temperatures.
- Most glues will last for many years when exposed to cooler conditions.
- Keep them away from ultraviolet (UV) light.
- Some glues can degrade when exposed to ultraviolet light.
- Avoid storing glues in direct sunlight if at all possible.
What to do with expired Glue
So, yes, glue has an expiration date, but what precisely does it entail? The consequences of using glue that has passed its expiration date are unknown.
What should you do if your glue has reached the end of its shelf life?
First and foremost, if your glue has turned moldy, we recommend that you do not attempt to “make it function” any more.
Running expired glue through your equipment has the ability to destroy perfectly good substrates and end products, which you do not want to happen. You’ll wind up wasting a significant amount of time and money in this manner. If the adhesive is poor quality, it is likely that the finished product will be poor quality as well.
In most cases, glue that has passed its expiration date will not provide enough bonding properties, and you will have to discard it. It’s critical to ensure that glue is disposed of correctly at the end of its life.
Using an adhesive, and specifically glue, after its expiration date might be a a concerning issues for anyone, the same way using any other household product after its expiration date.
To be completely honest, expired products have their own set of drawbacks, and the same is true for glue. When glue reaches the end of its shelf life, it becomes hard and lumpy instead of keeping its viscid consistency. This type of glue is essentially ineffective.
You will eventually fail if you attempt to join two surfaces of different items with an expired glue since the absence of stickiness will prevent any union from forming.
The use of expired glue may also result in discoloration and change in texture of the surface being worked on. This is due to the fact that expired glue tends to contain specific synthetic polymer compounds in its composition, which might change as a result of exposure to air.
When the glue has reached the end of its shelf life, these components lose their effectiveness, resulting in a change in look and consistency. This can result in the adhesive being rendered ineffective while also posing a danger to the surfaces on which it is applied.