In a shop, you could face a large choice of adhesives: some designed for particular tasks, others for joining more than one element.
In general, there are six main kinds of adhesive:
- contact adhesive, of which the most common are Evo-Stik and Thixofix
- woodworking adhesives – Unibond, for example
- cyanoacrylate adhesives or ‘super glues’
- two-part epoxy adhesives Araldite is the most popular
- two-part acrylics, similar in use to acrylics
- universal’ or general-purpose adhesives, such as U H U or Durofix.
As well as these main kinds, there are various professional repair adhesives – for joining glass, for mending PVC, and for joining polystyrene, as well as adhesives for jobs such as fixing wall tiles, setting up wallcoverings, and hobby work with paper.
When picking an adhesive for a particular job, there are various points you need to think about.
1st, what items are you joining together? The adhesive has to be perfect for both items if they are different, but the fundamental problem here is plastics and recognizing the plastic is the 1st task.
2nd, how necessary is strength? With wood glues, the bond can be as hard as the wood itself, while it will generally be weaker with metal and plastics. If strength is all-important, you might require to consider reinforcing the joint in some way.
3rd, how large a gap is there to fill? Often, joining two elements will also include a degree of gap-filling, and adhesives vary in their capability to cope with this. Contact adhesives, for example, require a slight gap in which to work, while cyanoacrylates won‘t work unless the gap is tiny indeed. Epoxy glues, on the other hand, will work with either bit of or significant gaps.
4th, what type of temperature is the adhesive going to be subjected to? Few adhesives (known as thermoplastic), such as contact adhesives and several ‘universal’ types of glue, will not withstand heal. In contrast, many others (known as thermosetting) will retain their strength up to moderately massive temperatures. This could involve when you are repairing crockery.
Finally, how essential is the appearance? Most adhesives dry to a pure finish, but few end up a pale creamy yellow. Whether or not this will show depends on the thickness of the glue line and, equally important, how well you clean away the excess; with many types of glue, it is tough to avoid some glue remaining.
The primary uses for contact adhesives are sticking light coverings, such as plastic laminate and veneer, to a surface and for best shoe repairs.
A contact adhesive is used for both the surfaces to be glued and left till it is dry. The two things are then pressed together, and the glue is left to set. With most contact adhesives, the bond is made immediately (which means careful positioning); some contacts provide a little time when the two surfaces can be adjusted.
Many contact adhesives are solvent-based, which means excellent ventilation is necessary and that naked flames and cigarettes should not be permitted in the gluing area. Acetone (nail varnish remover) or a special remover is required for a solvent-based contact adhesive; water-based contact adhesives can be raised with a damp cloth.
Glues for wood
The most common kind of glue for woodworking is the PVA (polyvinyl acetate) adhesive. Various brands are available, and the suggested solvent is usually warm water.
Where the joint might get hot or be subjected to moisture, you should use one of the specific thermosetting varieties often sold for outdoor use.
You can still get the traditional animal and fish glues utilized for woodworking: furniture restoration‘s primary use. It may be necessary to take the little piece of furniture apart at some point in the future.
These so-called ‘super glues’ set almost immediately provided a tiny amount of moisture present. The adhesive is used to one element, and the other is held against it for few seconds. The two elements need to fit almost correctly together for the glue to take.
Cyanoacrylates need attention in use because they can bond skin together – finger to finger, finger to the eyelid, or eyelid to eyelid. Most manufacturers now form a special-release agent to cope with this – make assured you purchase one unless provided as part of the pack.