Airbrushing TECHNIQUES
Freehand airbrushing

Freehand airbrushing is the basic technique and an essential part of airbrushing. You have to spray with care and produce different results by altering the airflow, the amount of color and the distance to the surface.
Using only freehand airbrushing is rather fast (compared to masking) and you can get a real "feel" in the picture. In contrast it is almost impossible to produce sharp edges and small details.
It is a key to all airbrushing to master the freehand technique.

Using a shield

A shield can be a great tool for improving the result of freehand airbrushing. With just a little more complexity and a slight reduction of speed you got the benefit of sharp edges.
You could either cut a special designed masking shield for the work you are doing or make a shield with many useful curves and angles once and for all.
Of course you can make masks that you don't hold in your hand but attach to the surface using weights or som low tac tape. One nice thing with the handheld shield is that you can vary the distance to the surface and thereby design how "sharp" your mask is.

Using frisket masking

Most complex jobs are best made using a frisket masking film. ( THIS IS THE ONE I USE. ) This is a tranperent film with a low tac glue on one side. You attach it to the surface and cut out patterns in the film using a sharp knife. The benefits of this is that the mask is surely firm and the masked edges are perfectly sharp.  This masking method is firmly recommended if you have to mask an area for a long period during several sprayings.  Another benefit of this method is that it is easy to transfer illustrations from scetches to the surface. Just draw a picture in graphite and put the frisket film on the picture. Some of the graphite now attach to the glue on the film and when you put the film on the surface you intend to use there is a guide for you when you cut the mask.  The drawback of this tecnique is that it requires more preparation and this slows the production down.  There are specially designed knifes with rotating blades for use with the frisket.

Masking paint

In addition to the abow described masking methods there is a special designed gluepaint for airbrush masking. This is attached using a regular paint brush, and removed by rubbing.
It can be used instead of the frisket but is some more nasty to the surface, this could result in loss of color. On the other hand it is easier to mask significantly small areas.
It is usually best to combine the different tecniques in the production of a picture.