Have you ever found yourself wondering why our glue has an expiration date? If so, we're about to let you know why.
So you ordered protein glue (hide glue) for a job about a year ago, and it's been sitting in the back of your warehouse since. You pull the skid out for an upcoming job and realize the expiration date on the carton just passed. Darn!
You think to yourself - why the heck is there an expiration date on protein glue? Well, there are a few reasons.
Just like a gallon of milk, glue is best used before the expiration date. No, your glue won't start to wreak like old sour milk, but it certainly won't work the same as it did when it was fresh.
All protein glues are made with all-natural products: gelatin, water, Epsom salts, corn sugar, and glycerin. Since they are completely natural "ingredients", they have a limited shelf life when added into a glue formula. For protein glues, this shelf life is typically one year.
After one year, you will begin to notice that the glue cakes don't look like they did when you first ordered them. You may begin to notice mold, or they may start to harden from oxidation. While it may be annoying to "waste" glue, if you notice that the cakes are moldy or hard it's a much better idea to discard them than to use them.
Glue that is past the expiration date will not provide the appropriate adhesion properties needed and you will likely have to discard it (along with poorly glues substrates) anyway.
Proper protein glue storage is the best way to keep your glue in tip-top shape for the entire shelf-life. Here are some tips on proper glue storage.
Also, make sure to double check your glue shelf life on the products Technical Data Sheet.