Label & Barcode Printing Labels Printer Consumables Barcode Scanning Additional ProductsUnusual Surfaces
To find the right label material and adhesive for your application can involve a number of factors, one of which is whether you need to apply your label to an unusual surface. Most commonly unusual surfaces for labelling can vary in terms of texture, material and curvature or may require performance in harsh conditions involving abrasion, moisture or chemicals.Surfaces | Curvature | Moisture | Chemicals | Surface Tension
Surfaces (Materials)
Application of a label onto any material or surface is determined by how well it sticks to what can simply be termed as the hills and valleys of the surface. Imagine looking through a microscope at a surface you can see there are small hills and valleys which the adhesive needs to adhere to. The more adhesive that adheres to the valleys and the tops of the hills, the easier the label will stick, and therefore the smoother the surface the more the adhesive will adhere.An application surfaces’ roughness or smoothness (texture) will affect the contact area of the adhesive. If the application surface is very rough, contact can take place only on top of the ‘hills’ and the ‘valleys’ of the surface and will not be in complete contact with the adhesive. The total contact area will be small and the resultant adhesion low.
When a permanent adhesive is required for rough application surfaces, the adhesive must properly wet the ‘valleys’, this is usually achieved with a hot melt or extra strong permanent adhesive. For removable adhesives, rough application surfaces are straightforward and removability is not a problem, it is very rare that the adhesion would be too high for a rough application surface.
Curvature
Application of a label onto a curved surface can result in the label peeling off if the best material and adhesive are not chosen. Test tubes and small bottles, where the surface is extremely curved are the most common difficult surfaces.Moisture
When you need to apply a label to a surface that is moist e.g. outdoor applications or applications where food is chilled and forms condensation, you will usually require a label with a specialist adhesive.Hot melt and solvent-based adhesives are recommended when moisture is retained on a surface because they do not contain water-absorbing substances.
Chemicals
Chemical resistance is essential when containers hold chemicals and the contents may be spilt whilst filling or emptying. Industrial chemical applications are massively varied in both the surfaces to be labelled and the environments in which the products are to be used. This makes the choice of adhesive critical, choices include acrylic, hot melt and UV hot melt.
Surface Tension
Surface tension causes the surface of a liquid to act as if it were covered with a weak elastic skin, for example this is why a needle can float on water.In labelling for the adhesive to adhere to the application surface there is a basic rule: the surface tension of the adhesive must be lower than or equal to the surface tension of the application surface to be labelled.
In other words, the adhesive will adhere if the adhesive has a stronger attraction to the application surface than to itself. If this is the case, the adhesive flows onto the surface without difficulty, and it is easier for the adhesive to bond to the application surface.
Surface tension is an important consideration when you are applying a label to an unusual surface, from choosing the right material and adhesive combination to the environment that the label is applied in.
There are a wide range of adhesives that have strengths on particular surfaces:
- Acrylic adhesives adhere well to an application surface with a high surface tension, like glass, metal and polyamide (nylon).
- Hot melt adhesives adhere well when you have a rough or uneven surface to apply to such as a chemical drum where the adhesive will ooze into the gaps.