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The ultimate guide to sticker and label adhesives

Ordering custom stickers and labels online not only means that you get to create and submit your own design, choose between your favourite sticker materials and get exactly the size and quantity you need. It also means that you can choose how sticky you want your stickers and labels to be.

The glue that is attached to your sticker or label material is referred to as an adhesive. Adhesives can be quite a nerdy topic - and we are all about it.

However, below you can find both: a brief overview to give you an understanding of what to look out for and a deep dive into all things adhesives. Here is what this article will cover:

  • What are my options: An overview

  • How do I choose the right adhesive for my stickers and labels?

  • Why do stickers have varying adhesive strengths?

  • How is adhesive strength measured?

  • How do I know what removable, permanent and high-tack adhesive is?

  • Conclusion

What are the options?

The custom stickers and labels we offer all fall under the category of pressure-sensitive adhesive. That means that the glue is "activated" once you put pressure on your sticker e.g. stick it to something and press it down with your hand.

These pressure-sensitive adhesives can be differentiated by strength. Degrees of stickiness, if you will. There are three commonly used adhesive strengths:

  1. Removable adhesive (also referred to as low-strength adhesive)

  2. Permanent adhesive (also referred to as medium-strength adhesive)

  3. High-tack adhesive (also referred to as high-strength adhesive)

Each of these adhesives is perfect for specific uses, but when you are not sure what adhesive to use, we always recommend opting for a permanent adhesive. Most of our eco-friendly and vinyl stickers and labels come with a permanent adhesive. The only exceptions are static cling and heavy duty materials.

Stacks of sheets next to various custom labels applied to different products

How do I choose the right adhesive for my stickers and labels?

Getting the adhesive right is essential to ensure your stickers and labels last and don't lift, peel or look low-quality, which could give your brand a bad image.

The most important factor for choosing a sticker or label adhesive is the surface you want to apply your stickers and labels to, how long you want them to stick and the conditions your stickers and labels will be exposed to.

Below, you can find a breakdown including these considerations for each adhesive strength.

Removable adhesive

  • Durability: short-term applications

  • Conditions: indoors, dry

  • Sticks to: glass, paper, painted plastic surfaces where you're worried about the paint peeling

Removable adhesives are perfect for advertising limited-time promotions or seasonal sales on flat, smooth surfaces like shop windows.

Permanent adhesive

  • Durability: long-term applications (up to three years)

  • Conditions: indoors and outdoors, temperature range of up to 80 degrees Celsius

  • Sticks to: glass, metal, paint, galvanized or powder-coated metal, paper, cardboard, wood, stone, leather, plastic bottles or tubs (ABS, PET/PETE/polyester plastics), fibreglass 

If in doubt, choose a permanent adhesive. It will stick to 90% of surfaces and is perfect for anything from promotions over branding and product labels to sticking to laptops and phones.

High-tack adhesive

  • Durability: long-term applications

  • Conditions: outdoors, industrial and extreme environments

  • Sticks to: low-energy plastic (polypropylene and polyethene) such as water buckets, wheelie bins and MX fairings, rubber

Our heavy duty material comes with a high-tack adhesive. It is used on machines that get jetwashed, engines and go-karts. Do not choose a high-tack adhesive becuase you want your stickers to be "really sticky". Only select that option when you know that a permanent adhesive will not do the trick.

If in doubt, we recommend speaking to your supplier. Most will be able to send you a sample to test for minimal cost.

And now, let's move on to the nerdier portion of this evening.

Why do stickers have varying adhesive strengths?

Stickers and labels have varying strengths of adhesive to make them usable in different conditions, various surfaces or even extreme environments.

The two factors that mostly define how strong the adhesive needs to be are:

  1. The surface energy

  2. How smooth a surface is

A smooth surface is easier to stick to simply because more of the glue on the back of your sticker touches the surface. The flatter the surface, the more glue particles can grip onto that surface, making it easier for your stickers or labels to bond. The more textured a surface is, the less there is for the glue to hold on to, meaning each particle has to be stickier for a similar effect.

Surface energy (aka surface tension) can be a complex subject, but basically, it's how sticky a surface is. The higher the surface energy, the easier a glue will stick. This image shows how surface energy changes between materials:

Graphic explaining the surface energy of different materials

Source

Want to find out more about surface energy?

Surface energy, in technical speak, is the degree to which a material surface will repel or attract.

Imagine a freshly waxed or brand-new car. The water beads and runs off easily. The wax creates a low surface energy, so the water cannot stick to it.

The technical term for a sticker sticking is 'wetting-out'. It describes the flow of an adhesive over a material surface. Good wet-out ensures maximum contact and helps achieve a strong bond.

The easier it is for the adhesive to 'wet-out', the better the adhesion. High surface energy values attract, whereas low surface energy values repel. Materials with higher values bond better because the allow the adhesive to wet out.

We measure surface energy in dynes per centimetre (Dyn/cm). To get even deeper into this subject, Adhesives.org is a useful resource.

How is adhesive strength measured?

A popular measure of strength is 'peel adhesion'. 'Peel adhesion' is an industry-standard test material manufacturers do to understand how sticky the adhesive is.

There are various tests used to evaluate adhesive strength; this image shows three ways to test glue:


Adhesive testing methods

Source

Manufacturers apply a piece of sticker material (also known as media) to a galvanised steel surface. It's then left for 24 hours (usually) before peeling off at varying angles. The amount of force it takes to peel the media is known as the 'peel adhesion'.

The angles of the test are typically either 90 or 180 degrees to test the adhesive in different conditions that may represent the real world.

Makers of self-adhesive vinyl conduct these tests in laboratory conditions on machines that look like this:

Adhesive test machine

Source

The force required to peel the media away defines how strong the adhesive is.

Here is a list of the forces required and the 'category' of adhesive-strength it falls into:

  • Removable adhesive = less than 19 N/25mm

  • Permanent adhesive = 20-28 N/25mm

  • High-tack adhesive = 29 N/25mm and up

Besides the peel adhesion test, manufacturers of self-adhesive label materials will vary the strength of the glue in 2 ways:

  1. The tackiness of their adhesive

  2. The thickness of the adhesive

To increase the tackiness, manufacturers use a slightly different adhesive formulation that will stick more. This is fairly obvious. 

However, the second way manufacturers vary the strength is through the thickness. This sounds counter-intuitive, but it works.

Most adhesive coatings on the back of labels are around 20 GSM. This can increase to over 40 GSM for heavy-duty applications and is especially if you are dealing with an uneven surface.

Remember what we said before: If only 40% of the glue is touching the surface the label is applied to, adding more glue to fill the gaps can work brilliantly. 

How do I know what removable, permanent and high-tack adhesive is?

Most sticker suppliers will tell you in the product description which type of adhesive your sticker or label will have.

If this isn't the case, however, download the material datasheet (if available). See an example here. The datasheet should tell you which type of adhesive the sticker or label is printed on. Alternatively, if it doesn't say; removable, permanent or high-tack, look for a 'Peel Adhesion' value.

Conclusion

Adhesiveness can make or break your stickers and labels. But we do not want to over-complicate it. This is why 95% of our stickers and labels come with a permanent adhesive.

If you are not sure if a permanent adhesive is right for you, you can:

You can browse our range of stickers and labels right here, check out our materials here or learn more about the world of custom printing on our blog.