Page 10 - November December 2010

Simulating Rust on Modern Freight Cars Dan Spalding
Introduction
Before proceeding, an acknowledgement is required. The tech­ niques set out in following article were demonstrated in a clinic run by Dave Hammaker at the Bay Area Prototype Railroading (BAPM) event that myself and fellow member Chris Prior attended in June this year. So many thanks to Dave for sharing his skills and experiences with his fellow modellers.
The feature of Dave’s technique that caught the imagination is that it doesn’t require an airbrush to achieve the desired results, and also it can be applied in a relatively short space of time, given a bit of initial practice.
Before cracking on, below is a list of the required materials:
• Packing foam – the grey stuff found in Athearn ‘Blue Box’ is
perfect
• Acrylic matt varnish aerosol – I’ve had good results with
Humbrol and it’s easy to source from Hobbycraft stores.
Dullcote also works fine
• Artists Matte Fixative aerosol for chalks and pastels – the
Windsor & Newton brand is available through Hobbycraft
stores
• Palette/saucer/old CD – for mixing paint
• Hobby knife
• Flat toothpicks
• Paper towel – for clean­up
• 180 grit sandpaper – for powdering chalks
• Water – for thinning paint
• Micro brushes – available via Amazon or tool vendors at train
shows
• Acrylicpaints–mattcolours:black,lightgrey,selectionof‘rust’
colours (shades of dark oranges, reds and browns)
• Pastel chalks – orange, assorted shares of red and brown, grey, black. Alternatively the prepared weathering powders of
choice.
Keeping it real
I personally find it easier to have some sort of visual guide as to how rust develops on real in­service cars. Website such as Railcar. com (www.railcarphotos.com) and Railroad Picture Archives (www.rrpicturearchives.net) have thousands of freight car photos, and a couple of hours surfing will yield useful reference material. A couple of examples taken by the author are included for quick ref (photos A & B).
Sanity check
Before slapping any paint about it’s worth repeating the usual caveat around painting or weathering, i.e. do not leap straight into attacking your lovely new £30 freight car. It’s suggested to use an old ‘scrapper’ from the spares box just in case things don’t initially go to plan. If nothing is immediately to hand, a cheap used Athearn kit will provide a canvas to practise on and also a supply of foam!
Paint your wagon!
First up is creating a roof rust effect, which can be applicable for covered hoppers and boxcars. From studying prototype photos it will be apparent that rust will range from a little orange/yellow blistering to an almost total coverage of deep­set black/brown rust. For both these extremes, and in between, the same basic method is employed. Photo 1 shows the how the effect builds with additional layers.
1. Creating a flat base
The first step is to give our chosen body a key to prevent the thinned acrylic from beading. You may also find that the talc in the varnish gives a slight bleaching effect on the base colour, which helps ‘age’ the car a little. Having washed your car body off to remove finger grease etc, give the roof a light dusting of matt varnish/Dullcote spray.
2. Oxidising the roof
The assumption here is that the roof to be weathered represents unpainted galvanised steel, i.e. a silver finish. If so, the base effect is where the galvanised surface has started to oxidise.
First cut a piece of foam to use as a paint applicator. Using a little sky (v light) grey paint thinned to the consistency of whole milk, gently dab the paint along the length of the roof in a random pattern. Avoid squashing the paint end of the foam too hard, as it will leave a block of colour not the ‘pock­marking’ effect. If in doubt, wipe off most of the paint from the foam onto a piece of paper towel before applying to the model, then if you need a heavier effect, do a second application. This fine spot effect is worth practising, as it will help in creating fine rusting effects later in the process.
Where the roof has been painted, you can either start by pre­ painting a couple of panels silver to simulate replacements and then ‘oxidise’, add some random silver patches by drybrushing to simulate bare panels showing through worn paint, or else just start adding rust. Again check prototype photos for guidance.
3. Light rust
Having let your grey/white oxidation dry (with the thinned acrylics this should be a couple of minutes), we can add our first layer of rust. At this stage two key points can be introduced that need to be remembered when applying the remaining paint and powder layers:
• Work light to dark
• Work outside to inside
Thin a small quality of yellow/orange paint as in the previous step. Visualise the rough size and shape of the rust patch you want to create, then start to lightly dab on the paint with the foam, working in towards the centre of your planned rust patch. Now switch sides and work from the opposite edge of patch back towards the centre. If you want to rust individual ribs/small patches, use a piece of foam cut to a wedge or a Microbrush.
4. Rust progression
Once your initial rust colour has dried, move on to a slightly darker shade, say a deep red/orange. Using thinned paint and the foam, go over the same area as before, working outside in but starting a little further towards the middle each time. The aim is to create a ‘halo’ effect of new light rust on the edge with older darker corrosion towards the centre line of the car. The paint should also be thin enough to be slightly translucent so as to let the lighter shades still show through, especially on the outer edges (see Photo 1 – right side).
Having applied two or three layers of yellow/orange shades should give a good representation of a lightly corroded roof as per the UP reefer (Photo 2). If the desired effect is some really nasty corrosion, keep adding more progressively darker layers, moving towards dark red/brown shades as per the EEC Boxcar (Photo 3). Again, check your photos for colours/patterns on real cars.
To give individual ribs more depth you can add a ‘shadow’ of thinned matt black along its length, applied with a toothpick. Allow a little paint to run to the edge of the car to simulate water streaks.
Once happy with the depth of rust effect applied, give everything another light coat of matt varnish/Dullcote. This seals the paint and provides a fresh key for the chalk/weathering powders.
Dusting down
Once the varnish seal is dry, it’s time to add some powdered chalk to give a bit of texture and also assist in getting a smoother transition between shades.
In playing with this technique I’ve tried ordinary pastels powdered on sandpaper and also prepared ones from Bragdon (www.bragdonent.com). These contain a dry adhesive, which is activated by the friction from rubbing the powder on. The upshot is that applying these powders covers more of the paint (handy for heavy rusting), while normal powders can be dusted on preserving more of the paint effect underneath.
10 rOUNdHOUSe
continued on page 16