There are five types of glues used in model building
and all have positive and negative attributes.
By far the most popular, are the regular MEK (Methyl Ethyl Ketone) type glues for styrene plastic.
Brands such as TESTORS (both tube and liquid), HUMBROL poly, TAMIYA (regular or super thin)
are the most popular.
Acetone or Tolulene based glues, commonly called "hot" glues, are used to glue not only styrene,
but also ABS, butrite, and acrylic plastics. These brands include TENAX 7R, SQUADRON,
MBS, PRO WELD, and PLASTRUCT PLASTIC WELD, among others.
Cyanoacrylate, or super glue (made famous by the CRAZY GLUE brand),is a fast setting glue that comes
in three different viscosities; thin, medium, or thick. There are many brands available
(the most popular is ZAP GAP),
and the better ones will also include an accelerator, de bonder, and non fogging glue.
PVC glues refer to the common white or craft glues. LA PAGE, ELMER,
and WELD BOND are all good brands.
Carpenter's or yellow glue are also listed as PVC, but are stronger than white glues, and dry to a flat finish.
It is the glue of choice for scenery in model railroading.
Finally there are the epoxy family of glues. DEVCON and LA PAGE are the most popular.
Epoxies come mainly as two part mixes, with either a five minute or three hour setting time.
The DEVCON brand is semi-clear when dry.
These are the five main types of glues used in model building.
In addition, there are a few specialty glues not commonly used but are great for certain difficult applications.
Rubber cement (not contact cement- they are to different things) is used for temporary positioning of parts
and is used in the Peeled Paint Weathering technique.
HUMBROL makes a product called CLEAR FIX. It is like a very thick clear gloss paint, and it works well
gluing clear plastic parts such as aircraft canopies and clear head lights.
It can be applied to painted surfaces with out damaging them,
but the set up time is long (three or more hours) and there is little strength to the bond.
HOW GLUES WORK IN VARIOUS APPLICATIONS
MEK and the "HOT" glues work by melting or softening the plastic surfaces to be joined. As the glue evaporates,
the plastic hardens and sticks together- just like a welded metal joint. It is the evaporation time that determines
the setting time of a glue.
"HOT" glues evaporate within a matter of seconds- which is why the parts to be joined must first be in contact,
and the glue applied with a small brush or syringe. Capillary action will cause the glue to flow along the joint,
and form a solid bond within thirty seconds. Regular liquid MEK glues can also be used this way,
but the set up time is longer. Because MEK glues evaporate at a slower pace, they can also be applied to each part
and then joined together.
Depending on the brand used, the set up time can be anywhere from thirty seconds to twenty minutes.
There are a few points to remember when using these types of glues.
It is the fumes caused by the evaporation process that can craze painted surfaces or clear parts.
The more glue used, the longer the evaporation process takes, the more likely damage will occur to delicate surfaces.
Cyanoacrylate glues work in the same way, and have the same problems as the MEK and "HOT" glues. The only difference is they don't melt the plastic. They cure, when exposed to oxygen, to form a very strong crystalline joint between the to parts. Because of this, Cyanoacrylate glues are used to glue dissimilar parts (white metal to plastic etc...), or non plastic (wood to wood etc..) together. Cyanoacrylate are what most experienced modelers use to glue photo etch and resin part together, to regular styrene plastic, or to each other