I got turned on to salt masking when I saw Chris Clayton’s large scale Ultramarine (took silver in the open category at GD’09). The basic premise is using salt+hair spray to make a mask allowing one colour to break through another. Below are the steps I went through on my Deathdealer project. It’s particularly good for rust, paint chipping etc…
Stage 1: Very roughly paint up the first coat which is the one you want to have breaking through, reds/oranges, metals etc… I used a basic drab green comprising of base colour + single shade & highlight and a wash. You’ll be building up a lot of layers so remember to keep the paint thin.
Stage 2: Once dry spray the required area with hair spray. 2-3 quick blasts from about 12” away should do it. Immediately drop on the salt flakes. The process is a bit tricky as you only have some control as to where the blasted things land… Leave it dry for around 10 minutes.
Stage 3: Once the hairspray has dried spray on your top coat i.e. the colour you actually want the model to be. You may also want to spray on a shade/wash. Avoid using a brush to apply the colour as the salt will come off quite easily.
In this case I sprayed the model black and once this was dry I brushed the salt off revealing the original colour below.
Stage 4: Use a sculpting tool, scalpel or scourers scrape more of the top coat off. It’s fixed to the hair spray and not the model so it comes off fairly readily. This manual stage give you great scope in where to remove the topcoat and as seen in the picture below you can remove fine lines if required.
Stage 5: At this stage the effect is very rough so using a thinned mix of the top coat wash the scraped area to tone down the contrasts (you can build them up with more control later). in this example I used a 1/1/1 mix of black/black Ink/water which I overpainted the majority of the model. Once dried this thinned mix gives a dappled effect which is quite good but you may want to make it thicker. I then touched up the edges with the original green.
This is a good base from which to further weather the model.