Technical > Adhesives
Sometimes, but not very often, you might want to stick something to bare metal. This usually works, providing the metal is clean and free from dust, grease and oil. Metal and adhesive will usually bond quite well and quite quickly. However, when something is made of plastic, or coated with something like a paint or a surface treatment, it is not always so simple
You see, there are two types of material surfaces one is called "High Surface Energy" and the other one, unsurprisingly, is called "Low Surface Energy".
What’s the difference? Well it's really in the way that things stick to them. In other words, it's the attraction of the surface towards other surfaces. for a guide to rough surface energy values for some common materials, go to Material Properties.
Basically, a High Surface Energy (HSE) material is one which will attract other materials readily. For example, if you look inside a glass of water, just at the edges, you’ll see that the water "curls up" towards the edge of the glass, showing that the glass has a stronger attraction to the water molecules than the water molecules have for each other.
The other type of material surface is, as I already told you, the Low Surface Energy (LSE) material surface. This is one which has very little attractionfor any other type of molecule. Probably the best example of a LSE type of material is when you see a recently waxed car after a rain shower. The water has a tendency to "bead" on the surface of the paint. This is caused by the LSE wax which repels the water.
In contrast, a HSE surface will appear like this under the same conditions;