Painting

Airbrushing looks so simple. Get hold of an airbrush, sway your hand about the model for a couple of times and as if by magic a perfect coat of paint appears on your model. Well.... guess what.....

It proved to be a steep learning curve though. Or more straightforward: a pain in the patootie. During the painting of my Shay, on which I worked in parallel during much of 2006, and my NS 7000 I encountered almost every conceivable beginner's error or mishap.

• Paint thinned too little
• Paint thinned too much
• Paint layer too thick to the point of runners ( and beyond)
• Corners not filled
• Paint dries in-flight and lands as grains
• etc etc

I lost count how many times I started over but it must have been at least five times. But (drum roll!!) I persevered, that is the most important thing.And by now I consider to be one the very enjoyable parts of a build.

Tools and paints used

Airbrush and compressor

Right at the start of the painting of my Shay I bought an airbrush and a compressor, which both still serve me fifteen years on. It is en investment, but it will last for long

• an airbrush: Hansa 581 (a link to the manual and the spare parts list)
• a compressor: Eurotech 10A (a link to the manual plus spare parts list). The compressor is provided with a pressure regulator and gauge with an integrated water trap, followed by a coiled water trap hose. In hindsight I should also have opted for an intermediate air tank which have resulted in an more even air flow, although in practise this has proved to be of little consequence.

I bought them from Airbrush Services Almere which have provided me excellent support and service ever since.

Paints used

For this model I used enamels.

I used a Testor's ModelMaster green that came very close to the NS darker green of the late 1930s. Black was just plain black. I don't quite remember which clear coat I used but I suspect it was also Testor's ModelMaster semi-gloss. My NS 7000 has a absolutely fabulous sheen on the paint that I have not been able to reproduce since.

There are basically three types of paint for model painting

Personally I did not get to terms with acrylics so far. I may have to try harder. I like enamels but I love cellulose paints for their excellent results. A spray booth with forced ventilation to the outer world is indispensable though.

WARNING: people often claim that acrylics are harmless BECAUSE they are odourless. I disagree.

• First acrylics are chemicals like all other chemical substances. There is simple sensible advice to chemicals: don't breathe them.
• Second acrylics dry very fast and overspray tends to dry midair. Well atomised overspray forms fine particles that remain suspended in the air and although you do not smell it, you breathe it anyway. And I simply cannot imagine that the paint that is deposited in your lungs in this form is harmless. So whatever paint you use always use a spray booth or a breathing mask, not a dust mask but a real filtered breathing mask.

Spray booth

I spray my models in a home made spray booth with forced ventilation which evolved over time. Read the story here.

Degreasing

The painting process starts with degreasing. Any grease will lessen the adhesion of your paint to the model. I don't remember exactly what procedure I used on the NS 7000 but this is current my way of working

• First an hour in pretty aggressive dishwasher soap of which the effect is supported by a few bouts of thorough brushing. 
• Once the hour has passed the soap is rinsed off with lukewarm tap water. Do not touch the parts anymore with your bare fingers.
• Then the parts are submerged in 4% acetic acid., again for an hour and helped by some scrubbing.
• Rinse once more with tap water.
• Fiannly a good flush with demineralised water concludes degreasing. This is to prevent mineral residues in tap water to settle as scale on the metal surface which will impede the paint's adhesion to the metal.

The parts are dabbed with kitchen paper towel. Then blow dry with an empty airbrush. You will be surprised how much water is blown out of all the nooks and crannies. Leave the model in a good warm place to dry for at least 24 hours in a dust free environment.

Primer

Most paints do not adhere very well to metal in general and brass in particular. A primer is needed. I asked an experienced modeller what he used for a primer and much to my surprise he answered "Alabastine spuitplamuur". Alabastine is a brand in the Netherlands, spuitplamuur is spray filler. From the DIY market. "Are you serious?" I replied in shock. Yes, he was dead serious. "Spray quick, spray thin".

I tried and failed. I drowned the model. Cleaned it and tried again. And again. But I got the knack of it. And yes spray not too close, quick and thin. The spray will spread out and form a silky smooth skin. It is like seeing a miracle happening before your very eyes.

Primer is merciless: it will show you all scratches you forgot to fill, all remainders of solder, all cracks, all hairs that clung to the model. But you can use it to your advantage as well. Today even before I even contemplate calling the model paint-ready I spray it with primer to reveal the flaws. I graze light the model to find them all and meticulously note them. Then I remove the primer again and correct the flaws and only then I really start thinking about painting the model. I did that at the end of the construction of the superstructure of NBS 118.

NS 7000 in parts freshly coated in primer. I described in detail the work break down structure before.

I made a video explaining the spraying of the tender frame of the NS 5000 I built later, so if you are new to the subject of painting you might enjoy viewing it:

Order of painting

Parts that are all black are sprayed black straight away e.g. the removable cab roof. Parts that will be green and black are first sprayed green. This is a rather counter-intuitive order of working. I was first inclined to spray everything black as a kind of second base coat and consider the green as a sort of bonus. I did that and I found myself confronted with a mighty heap of masking when following that order. I soon found this:

There is far less work in masking a green loco for painting black
than masking a black loco for painting green.

It seems odd but there is a simple logic behind it. Imaging a locomotive in the real world. Which parts where painted green? Well, those parts which can be cleaned relatively easy. These are the parts in relatively easy reach of the crew. So guess which parts can be masked with the least effort? Aha!!

I set out spraying the inside black.

I thought it would mean trouble if I would not do that first. In fact it was quite the opposite. I would have made life much easier if I had done green first and the inside of the cab last.

Masking

Masking is another of those jobs that takes tons of patience. Practise makes perfect, is a motto that also applies here. Use the same brand masking tape over and over again and you will learn to appreciate its properties and learn when to expect which result.

I use Kip 308 masking tape which I cut to size. A roll goes a looooooong way.

Bleeding

It may surprise you that after masking the cab is sprayed once more with green (left, top) and after that has dried with black (right). This is to prevent bleeding, creeping of black paint between the green paint and the masking tape, the paint being drawn in by capillary action (top diagram). Bleeding results in ugly, irregular black smears betraying your masking was not adequate and needing rework.

The trick is that I use bleeding to prevent bleeding. You first spray it in the same colour as the masked layer. If bleeding occurs it will be invisible because it is in the same colour!! (bottom diagram) The new layer does not need to give full coverage. It only needs to be thick enough to seal the openings at the edge of the masking tape.

Once that second layer of paint is dry, you can spray black over it with a great peace of mind as any bleeding will be stopped by the green sealing layer. Mind you, good masking is paramount to prevent bleeding, so work to the best of your abilities. But no matter how good you do your masking job, there will always be those nook and crannies where bleeding might occur. This trick helps to prevent bleeding on smaller issues in the masking. It does not help to mask sloppy work (excuse the pun).

First attempt

In a first colour coat

It looks nice but there were many things wrong. I had forgotten to remove some brass pipes, in some places the paint was too thick, the paint was uneven, and on the front of the running board the paint had landed in grains. I stripped it and tried again.

Further attempts

May 2006. A fresh layer after attempt no. X. I used the opportunity to swap the white metal head lights and safety valve for the same in cast brass as described in the Detailing section. After a renewed struggle I had a better result: