Weathering an O gauge class 31 diesel locomotive by Heljan. Time taken 12-14 hours Method I was determined to crack the method of weathering of Diesel locos. I’d tried the usual airbrush method but I just didn’t like the results, I wanted that grimy, oily, dirty, well worn look that you just can’t get with an airbrush, I wanted a build up a grime like in real life although in N gauge it’s hard to notice. So I decided to give weathering powders a go and after trying various techniques with them I’m now at the stage were I think I’ve got the results I’m after. Although I’m demonstrating my methods in 7mm it will work for all scales.  Firstly I remove the body, bogie side frames and the tanks, it doesn’t matter what you start on first but it is important that you study lots of photos of the loco your weathering, I use Flickr and general internet searches, just to get a general feel of how the average loco would look for example this loco, a class 31’s have a very dirty oily look to the bottom half of the body, it’s small details like this that will help. I tend to start with the wheels, I give these two coats of acrylic frame dirt and whilst the second coat is still wet I use a cotton bud to work in powders, again depending on the look I use rust, dark earth and black to get the desired look, for oil stained wheels I work in enamel gloss varnish again with a cotton bud and soon as it’s applied work in black weathering powder this gives quite a good wet oily look. Next I do the bogie sides (tanks are done in exactly the same manner), depending on the colour and look I’m after I’ll either paint on with a brush frame dirt or roof dirt, once dry I give it another coat and whilst still wet I start adding the powders, darker colours like black and dark earth if I’ve used frame dirt or more earth colours if using the roof dirt.  This is worked into the paint with a soft brush and once I’m happy with the look I seal it with matt varnish sprayed on from a distance and in small controlled bursts as you don’t want to saturate it.  Straight after I then add more powder and repeat the process building it up in layers until I’m happy with it. To get the look of oily and grease around axel boxes etc I I brush on enamel gloss varnish into the area I’m working on then with a cotton bud rub in black powder, I then give the whole bogie a light coating of satin varnish to give a slightly wet look. Weathering the body For heavily weathered locos I sometimes spay the entire body with roof dirt then remove it all off the sides, this leaves it in the nooks and crannies but if you don’t fancy doing that you can just paint the grills etc if you wish by hand which is what I’ve been doing on my most recent weathering jobs. I then start to apply the weathering powder, a blusher brush works great fit this, I used black powder around the grills and roof and a mix of light and dark earth on the sides, again like the bogies I build it up in layers, but once sealed with matt varnish I then remove it all again and start again.   To do this I normally use a scratch pen but I’ve found a peco track rubber works far better and doesn’t leave and tiny scratches, also if you are using a fibre scratch pen please use gloves and be careful of the small fibres left behind they hurt!  Also when removing the grime always remember to do it in a downward movement, to simulate rain etc washing the dirt away, again study photos of which areas tend to accumulate dirt and which areas look cleaner etc.  This process I sometimes repeat 2-4 times until happy.  Once you’ve got the look I’m after I add a final light dusting along the lower body then give it a final coat to seal it.  Buffer beams I tend to brush on powder seal then whilst still wet add more powder, the buffers themselves I paint with roof dirt then add a black brown mix of powders to the wet paint using a cotton bud. Once I’m happy with everything I use the empty airbrush to blow away any excess powder off the bogies, tank and body, it can then be put back together. Final touches like oil stains and leaks can then be added, again studying photos can give you a good idea where on the loco these will be.  On this class 31 I’ve achieved these by applying black paint with a small brush then with a cotton bud I’ve rubbed it off in a downward movement, again I repeat this a number of times until happy, I then very gently brush on satin varnish over this and whist still wet work in black weathering powder.