Confused? You may be if you’re a model maker or engineer trying to figure out the best metals and alloys to use for your models. Not only is there a big range of possible metals to choose from, but they can be finished in many different ways. So it’s hard to know which is the best one to choose. Let’s try and shed some light on the subject.
Makers of smaller models are often using both metallic and non-metallic materials. Styrene may be used for much of the model, but something stronger is needed to bear weight in part of the model. Many modellers choose metal tubing or rods and either glue or solder them on.
Brass and Bronze – Which to Choose?
However, model engineers may need to use metals in different configurations in order to create the part that they need in the workshop. For them, copper, bronze and brass are outstanding materials, particularly because they can be polished to give a brilliant finish if used on the outside of a model. They also give an authentic period look because in many cases these are the actual materials that would have been used.
Both brass and bronze are alloys. Bronze is mostly copper, often in combination with tin. Brass, on the other hand, is an alloy of zinc and copper. So let’s look at which is the best metal for model makers.
Brass is more malleable (easier to work) than the zinc or copper that it is composed of. It has a reasonably low melting temperature (900C) and can be poured when it is melted – very useful if you are casting a part. Other materials such as iron or silicone are sometimes added to brass to make it better able to resist corrosion. The downside of brass is that it isn’t as hard as steel and that it can develop stress cracks if it is contact with ammonia. Brass tends to be used in low-friction applications.
Bronze is beloved of sculptors and, incidentally, it has a much longer history than brass, probably dating back to 3500 BC. It’s widely used for modelling ship parts, especially on models that will be in water, because it’s reasonably able to resist corrosion from salt water. In fact, it is better at this than steel is, and suffers less metal fatigue than steel does. It gives a beautiful finish to models, with a deep lustre.
Unheated, bronze is hard and can be brittle. Heated to 950 C it will melt, but to some extent this will be influenced by the amount of tin in the alloy. One of the working methods for bronze is to “anneal” it. You heat it until it is red-hot, then cool it rapidly. This makes the brass easier to work with.
Copper and Aluminium
Copper is malleable, a great advantage in model making, and it looks great. But it’s also soft and can corrode, so you need to consider where your model will be stored. You can get copper in flats, rounds, hexagon and sheet form.
Prototype engineers will often use a wide range of metals, including, aluminium and cast iron. Aluminium is widely used for model aircraft and other uses. It conducts electricity, which can be useful, and because it’s so light, it’s ideal where a model is going to be very heavy otherwise. Like other metals, it can be melted and cast or machined into the required configuration.
If you’re buying metals, look for a supplier who is happy to supply small quantities and used to working with the modelling community – so they understand what you’re looking for.