Joints with Glue and Solder
By John Prentice
Here is my list of favourite glues (with UK trade names) and what I use them for. No doubt your list differs from mine and you have a different set of favourites by other manufacturers, but new modellers may find this of some interest as a guide to what is suitable.
Before I get going, a couple of general safety tips. Keep all glues away from small children. Do not breath in any of the solvent based glues. They will not do you any good. Never smoke when using glue. Some are very inflammable. Some that are not can be equally dangerous. Methylene chloride for instance is broken down into chlorine by the heat of your cigarette, and a lung full of that is no joke. A number of the glues can be irritant to sensitive skin and all should be kept well away from your eyes. However, the danger of sticking your fingers together with instant glue have been greatly exaggerated, but do be careful.
Neoprene Impact Adhesive. I use Evostik Impact but there are others. A very useful general purpose glue. Is very sticky, but strings. I use it for fixing dissimilar materials such as small plastic or metal parts to wood. You can either apply glue to both surfaces, allow to dry and then press them together or with just apply a small blob. Surplus glue can be removed with white spirit. Warning, contains toluene which is very flammable. Tip - do not use on thin polystyrene sheet, as it will soften the plastic and cause distortion.
PVA wood glue. I use Evostik Wood Glue (used to be called Resin-W). A white water based glue for sticking wood to wood. I use it for 3/4" modelling and in construction of wooden boxes or layout baseboards. Before setting, surplus glue can be removed with a damp cloth. Tip - if not screwed as well as glued, work needs to be clamped while the glue sets.
PVA paper glue. Similar to the above but thinner for use on paper. I use it for card kits. There are a number of makes available in art shops including the one aimed at kids called "Art Attack". Before setting, surplus glue can be removed with a slightly damp cloth. Tip - spring clothes pegs make good clamps when fixing card models
Pritt Stick. A strange PVA based product made by Henkel for use with card and paper. As it is not really wet, I use it for fixing in place paper posters on models. Can be used for card kits but I have found that joints are not very strong. Surplus glue can be removed with a damp cloth.
Solvent Welds. Polystyrene and similar plastics can be joined by making a solvent weld. Put the parts together and then with a brush apply a little solvent to the joint. I use it for plastic kits and scratch building from plastic sheet. It is much better than polystyrene cement which strings and adds thickness to the joint. Over the years many solvents have been sold for this purpose including combinations of toluene, amyl acetate, butyl acetate, and acetone. The original favourite was methyl ethyl ketone (sold as Mekpak), but the "nanny state" does not like us to use that now. The one that I am currently using is based on methylene chloride - see smoking warning. Tip - methylene chloride is the same solvent that is used in paint stripper, so keep it away from any painted surfaces.
Perspex Cement. You must use the proprietary products which are a little perspex dissolved in a suitable solvent (again sometimes contains methylene chloride). Here I have to admit that in fact I make much better solvent welds using chloroform, a small bottle of which I have had for years, but since you cannot buy that...
Instant Glue. Cyanoacrylate. Sold under a number of brand names such as Superglue and Loctite. Some are available in a thicker version. Add a little drop to the items to be joined and press them together. Sets in a few seconds. Joins most things. I now use it for most of the construction of white metal kits. Tip - in hot dry weather it doesn't set because dampness is required for the curing. Hold the work together, add the glue and then spit on it. Sets really instantly then.
Two part epoxy. The best known is Araldite although there are many others. Use the quick set version as the "original" takes 24 hours to cure, giving a harder and stronger joint but we modellers don't need that. Mix a little of the two parts together and then apply to the joint. In warm weather sets in about 10 minutes (much longer in the cold) but is only rock hard after 24 hours. I used to use it for all parts of white metal kit construction, but now only use it for joining the main body parts together where I need structural strength, for the rest I use instant glue. Tip - if the epoxy glue has not set, you can remove it completely with methylated spirit.
Of course for a lot of metal joints, such as on etched brass kits, I use solder. Elsewhere I have discussed the merits of lead free solder, but many people, including some quite eminent tramway modellers, have problems with soldering, so here are a few tips.
Make sure that the work to be soldered is completely clean. Use a file, abrasive paper etc. to achieve this.
Have an iron that is large enough. I use an 18 watt iron with a small bit for light work and electrical wiring, a 25 watt one for general jobs and a gas fired iron for heavy work. You must get the solder completely molten. When soldering large objects, the heat is rapidly conducted away from the joint area. Your iron must be big enough to replenish the heat loss. For very large objects you may even need to use a gas flame.
Use a suitable flux. For small joints (electrical wires etc.), resin cored solder is adequate, but for larger work I use a proprietary flux paste. Apply the flux both to the work and to the iron.
Now separately tin the iron bit and both objects to be joined. Make sure that the solder has covered all the area of the joint. At this stage you can see any parts that were not completely clean, as the solder will not stick.
Finally bring together the parts to be joined and apply the heat again. The solder already on the tinned parts and the iron will melt forming the joint. You may need to add a little more solder at this stage, but not much. When satisfied that the parts are in the right position remove the iron, but hold the parts in place until the solder has completely solidified.
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