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Glues and solders

Choosing glues and solders

The choice of a particular glue or solder is often a personal preference, built up over years of experience. These recommendations are suggestions for beginners to try but are not exclusive of other possibilities. Many glues have different manufacturers and are sold under different brand names in other countries. Postal restrictions on solvents and chemicals may prevent them being posted between countries.

Soldering is a skill that grows with a great deal of practice. As such, it is not recommended that a beginner use soldering on a first whitemetal kit as it is very easy to end up with a melted mass of metal that used to be a beautifully cast whitemetal kit. It is suggested that glues are easier to use for the first few kits.

Glues

Many glues can be used with paper, card, wood and plastic but fewer are suitable and strong enough for use with metals. Those that have been found to work include:

• Two part epoxy resin glues, such as Araldite, are useful for joining major parts of kits. Equal parts of glue and catalyst from the two tubes are mixed together to make an activated paste. The original version takes about 24 hours to set, so it is necessary to use clamps to keep parts in a fixed position during setting. The setting speed can be increased with gentle heat.
• There are fast setting versions of two part epoxy resin glues, such as Araldite Rapid and Devcon, that set in about 5 to 10 minutes, giving plenty of time to move and adjust parts into correct positions. They are useful for joining the main parts of a whitemetal kit. If the epoxy glue has not set, you can remove it completely with methylated spirit.
• Cyanoacrylate 'superglue' is useful for fixing small detail parts onto a model, as it sets within seconds. The liquid versions are probably easier to use than the gel versions, as they flow freely into the crevices between parts. Superglues set very quickly, so care must be used to avoid getting the glue onto your skin and causing accidents. Dampness in the atmosphere is needed to set the glue, so it doesn't work as well on a hot dry day. Do not use the glue inside a model with windows, as the long-lasting fumes from the glue will cloud and spoil the clear glazing.
• Neoprene impact adhesive is a rubbery solvent-based glue, with brand names such as Evostik. You can apply the glue to both surfaces, allow them to dry for a few minutes and then press them together for instant adhesion. This requires accurate positioning of parts. Alternatively, it can be used as a normal glue, with the parts held together until it sets. It can be used to fix the clear glazing in models.

Solders

Soldering is an advanced technique but in the hands of an expert it can produce excellent neat and strong results. The metal parts need to be clean and free from oxide to produce a good joint. Flux is used to help clean the parts in order to help the melted solder to flow and produce a good joint. It is probably best to practice extensively on scrap parts before tackling a real model kit.

The whitemetal model often uses a lead/tin 60:40 alloy with a melting point of about 185°C, so this is a critical temperature for soldering. Other models may use pewter, which is nearly pure tin, with a slightly higher melting point. It is helpful to have a temperature-controlled soldering iron to avoid overheating and melting the kit parts.

• Normal lead/tin 60:40 multicore solder wires contain the correct amount of flux within the solder to flow well. The melting temperature is also about 185°C, so the solder melts at the same temperature as the model kit parts, so it can only be used to solder large massive parts together. With great care, it can be used to building up casting faults, filling joints and repairing parts. When cool, it can be carved and filed with very similar properties to the original parts of the kit.
• Low-melt solders are available with melting temperatures as low as 70-80°C. Therefore, they melt at temperatures much below those of the whitemetal kit parts and they can be used more safely. Usually they do not contain flux, which should be purchased separately and applied to the joint before soldering.
• Solder paint and solder paste can be used to apply a thin layer of solder to two flat surfaces, before putting them together and heating them up to melt the solder.
• Lead free solders are now available, designed particularly for the electronics industry. They tend to contain silver and more tin, which leads to higher melting points. They tend to be harder to use, not produce as good, strong and flexible joints, but they are more environmentally friendly.
• Fluxes tend to be unpleasant chemicals, such as acids, that attack the surface of metals to help the solder flow. Some are fluid and can be painted onto joints with a small paintbrush. Others are pastes, such as one of Baker's fluxes. Particular fluxes are designed for particular metals and solders.