This week I have mostly been... messing with paint!

Context
On my long list of modelling-things-to-do is the assembly of a rake of coaches to make a 4-TC set. This will involve a cut and shut for the driving ends, plus two of the excellent Bachmann Mk1 coaches to form the TBS and TFK.

Whilst gathering the various bits together, my mind turned to how I would paint the driving ends, and importantly achieve a decent colour match to the two middle coaches. Whilst many colour variations exist in the prototypes, 4-TC units mostly stayed in their sets, so their colours were well matched.

Background
My modelling box contains a range of ~35 year-old Humbrol enamels, including some of the old 'authentic' range. Amazingly, almost all of these still flow and cover well after a thorough stir. However, the old HR135 (blue) and HR136 (grey) are no longer good matches - maybe paints have improved over the years, or perhaps the pigments have aged. Anyway, time for more paint!

I'd prefer to spray my new coaches, so a number of options exist:

• Railmatch or Precision spray enamel - no local stockist, expensive to courier since the 'mail of hazardous chemicals' rules, cans have a tendency to splatter
• Acrylic - less odour, easy clean, need to acquire airbrush (might be good to have for other jobs)
• Plentiful choice of brand now - best to keep to one if possible for consistency and compatibility
• Vallejo are getting good press, increasing availability, including a full rack locally - let's try some.
  

Colour Trials
What follows is not a particularly scientific approach and may not be repeatable - but it is the best I could do with what I had available. First I set up my TFT display to be accurate as possible: colour temperature (6500K), grey scale, brightness and contrast using Windows 7 'Calibrate colour' - other tools exist. Importantly, colour rendering varies by screen type and model, and even in JPEG compression, so the pics below may look quite different at your end

Here's some sample Vallejo shades available:

And here are some samples obtained from good photos of prototypes:

The upper group are from a coach and have measured RGB values overlaid. The lower group are from a class 37 and also have three Vallejo samples (with 9xx numbers) for reference.
On my screen, all these colours look a little too green to me. By the way, printing these was useless as my Epson SX colour rendering was appalling even using different colour profiles. It may be worthwhile if you have a super wizzy professional hi-grade colour printer.

Things looked promising, so it was off to the shops to obtain a few of the colours that seemed to be in the right range.

Once the paints were obtained - they are in eye-dropper style bottles which facilitate easy mixing and should reduce waste - the grand test began. For each colour, the bottle was given a thorough shake and roll, then two coats of each colour was painted on white card - the lines are useful to indicate the degree of coverage. The brush was cleaned and dried after each application. Here are the results after about 12 hours drying time:

This pic reveals several interesting things:

• the camera has rendered these colours quite accurately in daylight (no flash), everything being slightly darker 'in the flesh'
• some colours are quite close to the colour chart but some are miles off
• Dark Blue is lighter than Medium Blue - have I a duff sample?
• my old Humbrol authentic colours look quite wrong
• Bachmann's rail blue seems slightly darker than the prototype
  

Some of my older Bachmann Mk2 coaches have a slightly duller shade of blue, and most of my rail blue diesel locos (various makes) are a little lighter - somewhere between 962 and 963. So that's an area for further trials.

Conclusions
As if I didn't already know, don't trust the colour charts nor the bottles in the shop! From these trials, I found the best reasonable matches to a recent Bachmann Mk1 coach are:

• Rail blue - 70.963 Medium Blue (may benefit from a little 962 mixed in)
• Rail grey - 70.883 Silver Grey
  

And I need to splash out and buy an airbrush soon.

I'd be interested to know whether anyone else has tried this, whether your 'dark blue' looks lighter, and what you find works for you.

Postscript
These 'matches' only get close on a white undercoat/base. Further tests using a grey primer base coat revealed some issues - see next entry.