The one that sticks everything?
You’ve probably heard of it, you might even have it at home. We’re talking about the infamous all-purpose glue. The name adorns many a tube of glue, promising to make everything stick together. Wood to concrete, ceramics to plastic, polystyrene to steel and so on. And it does so regardless of other environmental factors such as temperature or mechanical stress. Sounds like a clever invention, doesn’t it? But does it actually deliver what it promises? To find out, let us first explain two important technical terms from the world of bonding.
No bonding without adhesion and cohesion
Adhesion
Bonding is the process of joining two surfaces together using an adhesive. But how is this bond created? Every surface has small depressions that are sometimes more (rough surfaces) and sometimes less (smooth surfaces) visible to the human eye. The adhesive settles into these depressions, interlocking as it cures and forming chemical bonds and physical interactions on a nanometre scale. The technical term for this process is adhesion. In general, the rougher the surface, the better the teeth and ultimately the bond.
Surface energy and surface tension also play an important role. These vary from material to material. For example, metals generally have a high surface tension, while plastics tend to have a low surface tension. What does this mean for bonding? Quite simply, the higher the surface tension, the better the chance of wetting the adhesive.
Cohesion
In addition to adhesion, the adhesive must have internal strength, known as cohesion. In their basic form, adhesives are initially liquid or pasty. Hardening occurs under very different circumstances. There is superglue, for example, which only hardens when it comes into contact with moisture. The opposite is true for screw fasteners. Here the adhesive only hardens in the absence of oxygen and in the presence of metal ions. There are also so-called epoxy resin systems, which cure as soon as the two components, resin and hardener, react with each other.
Why there can’t be one adhesive for everything
So you’re still not sure whether the term “all-purpose adhesive” makes sense or not. Although – the answer is actually in the previous paragraph. After all, when things like material surface, humidity, oxygen supply and various environmental conditions are important to the quality and durability of a bond, there logically cannot be one adhesive that covers everything.Fortunately, because otherwise companies like WEICON GmbH & Co. KG would not have a right to exist. The company has been producing adhesives and sealants for all areas of industry since 1947. From epoxy resin systems to superglues and silicones. The WEICON range comprises more than 400 products.
How do you find the right one for your application?
With such a large selection of different adhesives, the question automatically arises: How do I choose the right one for my project? In part 1 of the World of Gluing series, we looked at the three basic questions you should always ask when looking for the right adhesive:- What materials are being bonded?
- What is the size of the gap?
- What kind of stress, such as heat or moisture, will the joint be exposed to after bonding?
If, for example, you are doing small DIY projects for bonding metals, plastics and rubber, you are well advised to use WEICON Contact VA 100 Cyanoacrylate Adhesive. This adhesive is also used in many industrial applications. WEICON Epoxy Minute Adhesive is suitable for construction and assembly work where fast work is required.
Things get a little more special when, for example, aluminium or other light metals have to be bonded together. There are products for this, such as WEICON Aluminium Minute Adhesive.These are just three examples of countless adhesive applications. As you can see, there is a specialist for every “bonding problem”, no matter how unusual.
The WEICON Adhesive Finder will help you to find the right product. If you have any further questions, please do not hesitate to contact the adhesive experts in Münster. In the next part of the series “The World of Adhesives” we will take a closer look at one product category. We’re talking about cyanoacrylate adhesives, probably better known to you as superglue. Is it more deserving of its name than all-purpose glue?
Images: WEICON
