One often overlooked packaging component is label adhesive. Adhesive is critical – it ensures that your labels stay in place. But labels use so little of it that it can’t possibly cause problems for sustainability, right!?
Unfortunately using the wrong type of adhesive for eco-friendly labels and stickers can damage your sustainability efforts. Non-compostable adhesive can contaminate compost, and non-recyclable adhesive can damage machinery used in the recycling process. But it’s also important to know which type of adhesive works best with your chosen packaging materials as well. First, we need to know what types of adhesives are out there.
An adhesive at its most basic is a substance that sticks two materials together. So, it makes sense that they’re often categorized by how they form that bond between materials (also referred to as substrates). There are a few different ways a bond can be formed:
Pressure Sensitive Adhesive
This type of adhesive forms a bond when it is pressed on to a material – when pressure is applied. It’s most commonly used for products such as: stickers, product labels, household tape, and band aids.
This adhesive forms a bond between materials when moisture is removed (i.e. when the adhesive dries and hardens). You might recognize this type of adhesive in the form of school glue.
Hot Melt Adhesive
A type of plastic that is heated to melting point and then allowed to cool – forming a strong bond between a huge variety of different materials. This is the type of adhesive that you would find in a glue gun.
When reactive adhesive comes into contact with a specific substance, a chemical reaction occurs that forms a bond between materials. One of the most common reactive adhesives is water-activated adhesive. Water is applied to the adhesive (commonly a plant-based starch) which allows it to stick to a material. This adhesive can be found on envelopes, and some types of tape.
Although our first instinct may be to choose adhesives made from natural materials, a natural adhesive is not necessarily compostable or recycle-compatible. Similarly, a synthetic adhesive is not necessarily non-compostable. Some natural adhesives are derived from animal proteins, making them unacceptable for vegan or vegetarian products and businesses. It’s important to choose your label (and adhesive) based on your brand’s sustainability goals. It’s important that we do not look at sustainability in isolation. Deciding on the best end-of-life solution for your labels can be relatively simple. If the rest of your packaging is recyclable, you will need recycle-compatible labels. If you intend to use compostable packaging, then your labels will also need to be compostable.