To avoid costly errors and wasted resources, it is extremely important to use a label with an adhesive correctly matched to the surface it will be stuck to.
This is part of a series of guides to help you make more informed label choices to ensure that you are using the right durable label.
Each guide along with our free downloadable Label Specification How to Guide and Checklist will help you understand and work through the different durable labelling options available to you, in order for you to begin to understand your label requirements.
3 critical things that affect label adhesive performance
The permanence of your labels to your desired surface is dictated by 3 things:
1. Type of Adhesive
There are 3 main types of adhesive used for labels:
- Solvent acrylic based adhesives – used for durable labels, can be used outside and in harsh environments and last for over 2 years, often the life of the product
- Water based acrylic adhesive – normally used for paper stationary labels and packaging labels such as shampoo and wine bottles and they perform best indoors
- Rubber based adhesive – mainly used for adhesion to natural products but it has poor UV resistance so not suitable for long term outdoor use
2. Adhesive thickness should be appropriate for the surface texture
The thickness of the solvent acrylic adhesive on a durable labels should be matched to the surface material, texture and porosity that you are applying the label to, in order to achieve the required durability.
For instance, surfaces that are heavily textured would require a thicker, softer adhesive in order to fill in the texture gaps, ensuring that the full surface area of the label adheres to the required surface.
3. Adhesive curing time has an impact on label permanency
Solvent acrylic adhesives are used for durable labels as they cure over time and get more and more permanent with age.
Adhesive curing is the process of the solvent based adhesive transforming from a liquid to a solid through a chemical reaction with oxygen.
Once cured, these adhesives achieve a high strength, flexible to rigid bond that resists temperature, humidity, and most chemicals.
Water based acrylic and rubber based adhesive don’t have a curing time, they are as strong and as permanent as they will ever be immediately after applying them to a surface and will deteriorate with age.
If you don’t get the right combination of these 3 things; adhesive type, thickness and cure, for your specific surface application and process, your labels will fail. More than that, they may initially look like they work but the performance may degrade over time.
Understanding your application surface is critical for good label adhesion
The type of surface the label will be applied to will have a big impact on the adhesive if it is to be permanent for the life of your product or process.
You will need to consider:
- The surface material the label will be applied to
- The texture, shape, flexibility and how porous the surface is
- Surface energy, is it high or low?
- The environment that the surface is exposed to
What challenges does your application surface present?
You can now see that different surface characteristics along with the level of permanency you require for your labels will each present different adhesive challenges.Which categories does your surface fall into?
Smooth flat surfaces - Smooth metals, glass and high surface energy plastics all offer a very good surface for permanent labels to stay put long term, or for the duration needed for removable labels.
Textured and porous surfaces – Textured surfaces reduce the amount of surface area available for the label to stick to and porous surfaces will absorb more of the adhesive, using a thicker and softer adhesive fills in the gaps, adhering the label to a larger surface area.
Curved or flexible surfaces – Due to the nature of a non-flat surface, if you use the incorrect adhesive, the label material may naturally want to straighten out and come away before the label has stuck properly. Therefore an adhesive which grabs and cures quickly is needed to hold the label in place, fast.
Low and high energy surfaces – In simple terms surface energy refers to how non-stick something is. The lower the surface energy the more non-stick it will be. Surface energy is an important factor when considering the adhesive bond.
What environment will your label be used in?
Will the product, component or container surface that the label is applied to be hot, cold, frozen, damp, dirty or greasy?
Will the label come into contact with chemicals, solvents and extreme temperatures in your environment or during processing?
All of these factors will affect the performance of the adhesive and will therefore need to be considered at the label specification stage.
Other factors to consider if your labels are peeling or falling off
If you are having performance problems with your current label adhesion it may be worth considering these factors:
Storage environment – If your labels are not stored as instructed the adhesive may cure ahead of time or dry out, therefore decreasing or destroying the bond that would have been achieved. To ensure that your labels keep well until they are required they will need to be stored at 50% relative humidity, +/- 69.8 Degrees Fahrenheit in a sealed polythene bag.
Moisture – Moisture and contaminants present on the surface before applying the label would also affect the adhesive cure resulting in less adhesion to the surface. Applying your label directly onto a damp, cold or dirty surface can significantly affect the cure and bond.
Ageing – Non solvent acrylic label adhesive can dry out with age. Once a solvent acrylic based adhesive label has been applied the cure will become even more permanent over time.
The surface material has changed – If the labels are no longer sticking it could be as a result of a change in the material that the label is applied to, you will more than likely need to re-specify a label to get the correct adhesive for the job.
Don't touch the adhesive - Finger grease, sweat, oil, dirt and most definitely chalk coated rubber gloves will render label adhesive useless. Just think about how you apply your labels, if you touch the edge of the adhesive side when positioning your label it could be all it takes to make the label lift at the edge.
Ensure you are using an adhesive that is right for your environment
You should by now have a much clearer understanding of the factors that can affect the adhesion and durability of your labels and how important matching your adhesive to your surface and environment is.
You don't need to figure out what adhesive you need, a computer imprintable durable label specialist will have the expertise to be able to recommend the right label for the job, so you can be sure that you will be getting the permanency required for your needs.
Want to find out more?
Read our next guide - Ensuring your labels withstand your environment >
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