There are many ways to do rust effects on a model. Some rely on special products. Some use hairspray, salt, ground pigments, make-up powder and so on. This tutorial uses paints that you may already have.
The most basic rust effect I use is to just coat the metallic part in a thin coat of GW Tin Bitz/ VGC Tinny Bitz. This is an easy way to add a bit of tarnish to a weapon or other metal part that looks too shiny and new.
Another quick technique is to paint the part in a colour such as GW Vermin Brown and then [url=http://www.cheddarmongers.org/prod/drybrush][b]drybrush[/b][/url] with a silver metallic such as MP Chainmail. The advantage of this is that the drybrushing tends to pick out edges and rivet heads, exactly the parts that due to wear would show less corrosion than other parts of a heavily rusted item. You can, of course, combine this method with the Tin Bitz wash.
For larger areas of rust a slightly more involved method can be used. We will assume the item is a large metal surface that was unpainted and has corroded. Start off by painting a base coat of dark brown. Vallejo German Camouflage Brown is the colour I usually use, or sometimes Vallejo Burnt Umber. You do not need these specific colours, just a brown that is dark and on the dull side. The pincer and saw of the dreadnought shown in this article were painted this way.
Modern modellers are lucky in that the internet supplies a massive source of reference material. In a few seconds you can find scores of images of a “rusty truck” or whatever other items you may be painting. Use these to study the patterns and colours of corrosion.
When painting large rusty objects a good policy is “Silver Twice”. By this I mean you add two stages of silver to the model, one before most of the corrosion effects and one after. To the dark brown object you have painted drybrush it with a colour such as MP Chainmail. This will pick out edges and bolt heads and add a few scuffs and patches that look like uncorroded metal showing through. You can also apply some dabs of silver with your sponge and we will deal with sponge painting in a moment. If you are making marks as scratches make them consistent with the use of the object. In my dreadnought you can see scuffs on the buzzsaw are circular while those on the pincer represent damage when cutting something.
After the first application of silver it is time to add some more rust colours. Rust has many colours and the range of colours may be greater than you assume. The next colours do not probably need to be applied in the order I list them, nor do you need the exact colours.
Over the brown and silver the next colour I would usually apply would be GW Vermin Brown. Another shade of orange-brown can be used, of course. For this brown you are going to apply it with a bit of sponge. The foam sponge that comes in some blister packs of figures is fine. Apply a little paint and then dab lightly on your model. Play around with this on a scrap piece of material and you will find there are a lot of effects you can do with a sponge. Dab, smear, smudge, wipe and wipe off. A pretty useful tool for other random effects. Apply some dabs of Vermin Brown but don’t over do it. You can always add more later. With rusting less can sometimes be more.
After the orange-brown we can perhaps add a red-brown colour such as terracotta. Again, use your sponge and dab away, but in moderation.
For the next colour we will use a dull-yellow or mustard colour. GW Bronzed Flesh, GW Bucolic Brown and the B and C shades of Foundry Ochre are all possibilities. Some rust gets very light and may look yellow. Apply with the sponge.
If you are happy with how your piece looks, apply some more silver to simulate places where the rust has worn away. Dry brush but you can also use your sponge a bit too.
That is about it for the basic technique. A little [url=http://www.cheddarmongers.org/prod/blackink][b]blackinking[/b][/url] will add to the effect and provide grime and dirt around boltheads and other features. You can apply a thin wash of Tin Bitz if you desire.
The sand ladder on the Land Rover is an example of a very quick paint job. The bare plastic was undercoated/basecoated with VMC Burnt Umber. Vermin Brown was applied with a piece of blister pack foam. The sand ladder was then lightly drybrushed with MP Chainmail.
The model piece you want to appear rusty might represent something that has been painted and rust has begun coming through. In this case paint the piece the desired colour and include a dark brown stage to your sponging. The red painted areas of the Dreadnought have been treated this way. The blue wing of the Land Rover was given just a few dabs of Vermin Brown to represent light rusting.
Rust will sometimes form streaks where water runs down from a projection or damage over a period of time. Many modellers use special paints for these effects and then smear the paint downwards with thinner or white spirit. If you do not prepare properly the use of such solvents may damage the rest of your paintjob. Streaks can be done with more conventional acrylics. Use Camouflage Brown or Vermin Brown and with a fine brush dot lightly to form a line running down from the feature. Add a few dots of other rust colours to build this up but do not overdo it. Studying reference pictures of rust streaking can be invaluable here. For something such as a dreadnought remember such rust streaks will form when it was left standing around so may not be perpendicular to the ground when it is in a dynamic pose.
The rivets on the front of the dreadnought show a little bit of streaking. You can also see some minor streaking on the left rear of the Land Rover above the wheel where the paint has become damaged.
Larger areas of streaking, such as from the top of a panel, can made using your sponge.
An interesting rust effect I came across but have not yet tried is to apply cinnamon, paprika and nutmeg powder to a model while the paint is still wet. I may try this using a clear matt varnish.
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