Well, so far so, eh, good I suppose. Here are the pics of my JU-88 with a salt weathering applied to it. Its somewhat OTT (I'm practising). My apologies for the pic quality, its my webcam thats to blame.
Basic info: The plane is a 1:72 Ju-88 A by Revell. The kit is a horrendous fit and severely underdetailed. The side of the box blaitantly lies about the alleged detailed cockpit.
All paints were enamel. The undercoat is a Humbrol flat aluminium, the camo is Revell enamel for the green and grey, whilst the underside is some blue-ish grey enamel I found lurking around in my paint box. I used normal kitchen salt for the paint weathering, and a burnt umber oil thinned with mineral spirits for a wash. The aircraft was coated in revell clear gloss after chipping the salt off prior to decalling. After the wash was applied the AC was coated in revell clear flat. The exhaust trails are powdered charcoal applied with a brush.
This is how I did it:
Step 1: I assembled the aircraft deviating somewhat from the instructions so I could paint the AC in one piece, kind of like with an armor kit. When I was satisfied with the assembly, I (brush) painted is a flat aluminium colour. I used a brush out of sheer laziness. I chose this model as a testbed, so took a few neatness liberties. Airbrushing would have been the preferred method.
Step 2: When the paint was dry, I sat down with a tub of salt and a small bowl with water. I dampened the parts of the aircraft I wanted weathered. These were (as you can see in the pics below) wing roots, leading edges, control surfaces and just general splotchiness.
note: I didn't research properly where this weathering would have occurred, so don't take my weathering patterns as some sort of template.
it is inaccurate!
On these damp spots I added the salt granules. I used a brush tor this. When the salt was on the AC I found I could arrange them to a certain degree by pushing them around with the brush. Obviously where I wanted more weathering I used more salt. The salt dried pretty quickly and pretty solidly. The salt will now act as a mask for the aluminium parts I want to be poking through the paint.
Step 3. I applied the first coats of paint. I started with the underside. This was a blue-grey enamel applied by airbrush. I thinned it with mineral spirits to a milky-ish consistancy. I applied it in light coats. Because I did this outside on a hot, dry day, the paint dried almost immediatly.
You could deviate from this step by applying a coat of paint similar in colour to a primer coat of yellow/green. Then add more salt on top of already salted areas, so you get the impression of paint weathering through to primer through to bare metal.
After this was dry, I used tape and post-it's to mask the underside for the grey-green light shade of camoflage. Then followed the masking for the second camo colour. I found that masking a straight line on a compound curved surface with salt added to it proved a tricky job, but it resulted in a very satisfying result.
Step4. Finally when all the paint was dry, I went to work with rubbing the salt off. The salt's natural edges make for a realistic edge on paint wear. Its edges are superiour in effect compared with more traditional after effect use of brushes, which tends to be rounder and seem to protrude. This is obviously because its painted on top of the paint scheme. Salt weathering simulates the way paint would flake off naturally.
I found that using a cloth didn't work all that well, but that could be attributed to the type of cloth I was using (old bit of jeans.. Don't use it). The salt is pretty jagged, which means it can pull tufts of cloth out. Something to be aware of before applying some gloss afterwards. I ended up using my fingernails and a stiff brush. My fingernails dug into and scratched the undercoat here and there, leaving a dark green (colour of the plastic underneath) scratch along the surface. try and remember where you put all the salt, otherwise you'll end up with some surprise rivets here and there.
Thats all there is to it, basically. From here on its the usual gloss-decal-weather-flat treatment.