Adhesives are made to stick. So, the more adhesives you put on something, the better it will stick, right? Actually, that isn’t right. There is clearly such a thing as too much adhesives and it is important that you recognize that. When you do use too much, depending on the type of adhesives that you have used, you will notice a range of problems. Below is a list of those problems, as well as possible solutions.
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Instant (Cyanoacrylate) Adhesive
The main problem with instant adhesive is that it has a slow cure time. This is because the ratio between moisture and adhesive is very low. Trace amounts of moisture are needed to deactivate the stabilizer of the adhesive itself. These trace amounts can be found in the air and on the surfaces that are bonded. If, however, you put too much adhesive on, there won’t be enough trace amounts of moisture to start curing it. The solution is simple: you actually need to find the smallest amount of adhesive necessary to make the desired surfaces stick together. Do also make sure that you regulate the temperature and humidity levels in the area where you are using the adhesive.
Another problem is that a crust or white haze can appear on the finished piece. This is because you need to apply the right amount of cyanoacrylate for the size of the surface. If you put on too much, the cure time will be very slow, resulting in some volatilization, which then falls back onto the adhesive and leaves a white residue. Again, the solution is to only use as much adhesive as is necessary.
With these adhesives, the cure can be slow or incomplete. This can be because the gap between surfaces is too large or because it was exposed to oxygen. The solution is to make sure you use the right amount of adhesive and to make sure you don’t have any excess. Always wipe off excess with a clean dry cloth first.
You need to find out, if your bonding doesn’t work properly, whether this is caused by a cohesive problem or an adhesive problem. In other words, is the issue how your adhesive bonds with the component parts, or with the bond area?
If your adhesive fails, this means that it doesn’t bond to one of the surfaces. This is known as interfacial failure. This can be caused by things such as contaminants or dirt, which is why you must clean the surface properly first. It is also possible that the surface is simply too smooth and needs roughening a bit.
If you are using plastics, you may be using the wrong adhesive, or you may have to treat it with a primer first. Finally, if there is a bond problem around the joint, it is likely that there is some sort of design fault.
In case of a cohesive failure, you will find that the joint is under stress. This means that it does stick, but the layer of adhesive starts to crack and tear. This happens if you are expecting too much of your adhesive (like supergluing your own feet to the ceiling).