Prepare surface for paint by washing with soap or alcohol.
Start with a clean airbrush. If it wasn't cleaned after the last use, shame on you. Clean it now before starting a new session.
Thin desired paint to roughly 2% milk consistency. 2/3 paint and 1/3 thinner. Mix well.
Connect to air source and test spray on scrap plastic. Adjust paint/thinner ratio as needed.
Rule of thumb: Finer spray pattern = more thinner in paint
Apply thin light coats. Start with lightest colors first. Let paints cure completely before any masking.
Supplies: What you need to start:
I (Bryan) use Kleenex tissues slightly soaked in water as a masking material for cockpits, wheel wells, turret hatches, etc., in order to keep overspray out of those detailed areas. The Kleenex is very pliable when damp and can be wedged and worked into some pretty small areas. When it is dry, it holds its shape and place very well. It is best to let the Kleenex dry overnight before you paint.
When the painting session is done, wet the Kleenex again and remove.
Although I rarely use a primer coat, Brett swears by them. If you have a good primer coat, you give the top coats something to adhere to, thus limiting the possibility of lifting top coats off when you remove the masks (in hindsight, I am going to start priming my models as I have a problem with the top coats lifting off with my masks).
Take tape strips and press them once (gently) onto the palm of your hand to reduce the tackiness even further.
Apply several strips at a time to the edge of your hobby desk, etc.
Take your hobby knife and cut the tape strips down the middle so you have two pieces of thin tape with a straight edge on one side.
Use these thin strips to "outline" your camo pattern (using straight side of tape - of course) then fill in the large areas with "full size" masking strips (be sure to use the palm of your hand to reduce tackiness - this prevents the tape from lifting primer/other top coats.
I (Bryan) have only tried this once and had varied results, so try at your own risk. The secret to it is having a pressure adjustment on your airbrush so you can reduce the pressure to where you don't blow the mask off the model.
Cut paper masks to the desired shape and pattern.
Dip them in water and place them on the model in the desired location. Remove any excess water with a towel/tissue. The surface tension of the water should keep the mask in place during painting. Simply remove upon completion of painting or whenever the paint dries.
I (Bryan) have tried this by both hand-held paper masks and masks set slightly off the surface of the model with tape, etc., with good results.
Cut paper masks to the desired shape.
If hand-held method, simply hold in place over the desired spot and paint. If you find it difficult to hold the mask while painting with the other hand, simply use alligator clips, etc., to hold the mask while you paint.
If using the set-slightly-off-the-surface method, roll pieces of low-tack masking tape or 3M "Stick-All" (a rollable putty type of material used to hold posters, etc., to walls without nails, etc.). Press the tape or putty onto the paper mask so that the mask is roughly 1/16- to 1/8-inch above the model.
Spray at 90 degree angles to the mask as much as possible to limit the amount of "bleed through" (a dusting of color in places you don't want it to be).
If you do have "bleed through", simply remove all the masks and touch up the affected areas by hand with the airbrush.You can also use a very fine sanding stick and very, very gently sand the overspray off the other color. I really mean gently as it is easy to sand too hard and go through to the plastic (trust me, I have done it too often).
If you are brave, grasshopper, you may attempt this method, but be prepared for the potential disappointments.
The secret to freehand airbrushing is good-to-excellent control of the airbrush you possess. You need to go very, very slow and do many thin (consistency) and thin (width) passes in order to establish a paint border line/area. From that border you will fill in the area with the camouflage color. Do not be worried if you overspray onto other colors. You just have to be prepared to do lots of little touchups with this method. Needless to say, this technique only works for "soft-edge" camouflage. For "hard-edge", refer to the other masking techniques.
The only advice we can offer is to get out there and use your airbrush. You will never get better at it unless you practice. Learn from your mistakes and apply them to the next model. Remember, Easy-Off oven cleaner can strip off ANY mistake!! 8)
Many thanks to Brett for the set-up of this cool-looking document. All I did was add to it. Thanks, man!
Editor's note: I couldn't put this article on the web without the pictures of the two people who made it possible. Here they are in all their glory.