Real trains get dirty – Phil Parker shares how to replicate this on models to make them more realistic, using a selection of accessible techniques and products.
Before attacking any model, go and take a look at the real thing. These photos of a Midland 1F were taken at a Borrow Hill shed and happily, they keep it in typical working condition - grubby, but not really filthy.
The prototype might use gloss paint, but this looks toy-like on a model. A little bit of shine showing through the dirt is a nice idea if you imagine your loco is well cared for by its crew. Polish the paint gently with a cotton bud dipped in car colour restorer (T-Cut) or even mild metal polish (Brasso). Try this on a hidden area first if you aren't sure how the paint will react. When polishing, try to imagine where a real cleaner would be able to reach, or a proud driver would wipe an oily rag.
We are going to use an airbrush to add the first layer of dirt. To make cleaning the wheels easier, a bit of WD40 is applied to the tyres as paint won't stick so well to this.
In the spray booth, the lower areas are heavily misted with earth colour and rust, the top dark grey and a hint of black and everywhere with track colour (dark brown). There's no science to this, we are just chucking mucky colours around. You might need to consider where your railway is set - if modelling a Cornish clay line, the model needs plenty of off-white on the lower regions as you'll see from photos. Sitting it on a box makes spraying under the valances easier. We are assured it doesn't affect the taste of the cats' dinner.
When spraying, it's essential you take precautions to avoid breathing in paint vapours. This spray booth came from Expo Tools and uses easily replacable filters to clean the air rather than needing a pipe poking out of a window. It's a wise move to wear a suitably rated face mask at the same time and Expo can supply one with a cartridge filter for a price of a couple of coffees.
Move the wheels occasionally during spraying to avoid clean "shadows" behind the spokes and valve gear. On a DC model, a 9v battery will do the job. For DCC, you are better placing it on the layout and rotating the wheels about 1/8th of a turn.
The end result is a really filthy locomotive. You could stop now if that's the state the prototype ran on your railway, but we are going to go further.
Before the paint has hardened, a stiff brush damp with thinners removes most of the weathering. Work downwards as though the dirt has been washed away in the rain, the colour remains in nooks and crannies.
Another quick blast in the spray booth and now the loco looks as though it's been cleaned but the dirt is returning.
Surfaces that would wear in use such as steps and handrails are tickled with a dry brush of Metalcote gunmetal. The slightly shiny paint contrasts nicely with the dirty model but don't overdo the effect, subtlety is the key. Finally, weathering powders not only simulate dirt, but they also provide texture. Try some rust colour around the bottom of the smokebox door, bufferbeams and cylinder fronts.
Now, let the paint dry fully, clean the wheel treads and your loco is ready for realistic service on your layout.