I've copied-and-pasted this entry from Ian Cowley from the RAF GB for reference purposes ...
Postby cowleyi » Tue Jul 10, 2018 8:36 pm
Apologies, the weekend was the intention but that was squeezed out and then I have been ill for the past couple of days so I haven't got around to doing my tutorial. Right on we go. once the canopy masking is up and things like wheel wells are either masked or filled with yellow tack then I give the model a coat of Tamiya fine white primer. This will reveal any errant gaps or fit problems. Once dried I have then airbrushed on a preshade. In this case it was Gunze midnight blue. This is thinned to skim milk consistency with gunze acrylic thinners and shot through a Tamiya HG superfine airbrush (0.3 Tip) at low pressure round 8-12 PSI. The key here is a nice fine line. It doesn't matter about accuracy along the panel lines themselves as the wandering line will help add depth. I make sure I get a good line in the joins between wing/tail and major moveable surfaces - so ailerons elevators flap and rudder. For this particular job I made my own custom mix for PRU blue as described previously. This was shot through a Harder and steenbeck infinity 0.3 The key for me is thin paint and low pressure. I always do some practice spraying on paper before I get underway. Sometimes there are issues so its empty the contents and do a clean and start again. When I can get nice fine lines consistently I'm happy. I also keep some lacquer thinners handy in a jar so I can do a quick squirt to clear the tip if needed in case there is drying on the tip.
I will do each section of airframe slowly and build up the coats first round the preshade do a practice on paper to ensure the airbrush is behaving every time I finish a small section and this should help to get the right level of opacity over the preshade. This is a matter of preference. I like it to just show through so the preshade is just a little darker. Once (say the port tailplane preshading is sort of done just work your way round the airframe. In all cases I can vary the level of opacity a little bit. lighter in the middle of the panels (less paint). In order to accent the panel interiors once all the airframe basic paint is added I will add a drop or two (up to you how much you want to lighten the panel interiors) of gunze off white. this lightened mix will also be brought to thinness and once I am happy with how the airbrush is behaving I will try to do a lighter spray on the interior of major panels (interior of moveable surfaces) and interior of the panels. It might look a bit stark at the moment but don't panic, a filter will pull it together.
once dried, I seal with pledge one go or future or what ever floor polish or gloss clear coat - this should be chemically strong enough to cope with follow on treatments. decals on seal decals with a gloss clear coat or the same floor polish formulation. I use an artist acrylic warm sepia mixed with water and a dash of dishwashing detergent and apply with a fine brush using capillary action to fill the panel lines. allow to dry and then with an old lightly watered or spit moistened cotton garment old undies, handkerchief etc (emphasis is on lightly moistened --- to dry = no good, soaked = no good as it will strip all the wash out) It's not a complete disaster is some of the wash does get stripped out of the finer lines as long as you work in the direction of airflow. once this is done its good to take a break and come back and check it over to ensure there is no errant wash where you don't want it. If you seal it with stray wash on... that's it... it aint going nowhere. I don't know how many times I have found some wash where I didn't want it to be. Happy with the wash .... good now get some dullcoat (I use testors dullcoat) I decant from the little square bottle into a smaller bottle and dilute to a 30% sediment 70% diluent mix. Just me - still gives a good dull finish. once sealed with dullcoat and dried then its time to weather. First stage is a filter, for me, because I do my basic paint work in acrylics I do my filters in enamels. This is a 5% paint 95% diluent. I will either use a premixed MiG filter or use old humbrol enamels. I use white spirit as a diluent --- a few drops into an artists pallet pot. I mix the paint well and put a spot into an artists pallet cup mix. dip a paint brush in and the paint should just be visible when you drain the brush ---less is better as you can always add another filter
Here there are no rules on colour - I used an insignia blue in this case but you could use bright colours or colours a little darker or lighter. you can even do control surfaces one colour and the rest of the airframe another colour. seal this in another light coat of dullcoat.
Chipping can be done at this stage I used some games workshop acrylic that was a around the blue grey and chipped the wing root sparingly, then some Games workshop chainmail was added for harder scrapes but kept it to a minimum. Then I have added a slightly diluted mig neutral wash (another enamel) which is a dirty grey. I think it needed a little dilution with white spirit in my trusty artist pot thingy.
The final stage is post shading between movable surfaces and wings and exhaust staining. This is a mix of Tamiya red brown/nato black/flat base/and a touch of smoke. you can fiddle round a bit with this mix anywhere between straight black (but I would not use a pure black always a rubber black or nato black) and that red brown/black mix. The key here is getting very fine lines and a nice diluted mix and build it up to the depth you want.
This is not fixed in stone. look at some of the armour modellers like Mike Rinaldi's work and his use of oils ..... he has in my opinion done some stunning stuff and for me that is another road I will travel one day in 1/144 scale. hunt round the web and find people who do stunning stuff at larger scales and see what you can take away from it.
Hope this helps ... I'm ready to always help out so if there are questions fire away.....Happy Modelling!