Taken from an on-line FSM acrticle:
Salt Weathering and Digital Camouflage
By Mike Pabis
Adapted from FSM article
Items needed:
1. Paint brush
2. About a tablespoon of ordinary table salt
3. Water
4. Airbrush and paint
5. Toothpick
Time Involved: minimum two days (mostly drying time)
Steps to weather models with salt
1. Complete your model to the point where you have primered the pieces you want to weather.
2. Determine what you want your bottom coat to be. This should be the color that you want to show through the topcoat when everything is complete. Example, if you are planning on showing chipped paint on an aircraft, your bottom coat would be aluminum and the topcoat would be the aircraft’s color.
3. Spray on the bottom coat and let dry for at least 24 hours. Note, try not to use the metalizer paints as water beads off the dried paint and makes it very difficult to place water where you want.
4. Once the bottom coat has sufficiently dried, wet a paintbrush with water. Use a thinner brush for most applications. “Paint” the water over the area where you want to show the bottom coat. On an aircraft, this would be at the edges of the wings, worn areas of the fuselage and areas where other items come in contact with the aircraft. Armored vehicles would show through on the corners and exposed edges. Basically, think where paint would chip off on a vehicle and apply the water there.
5. After applying the water, get your table salt and sprinkle the salt on the wet areas. Depending on how much weathering you want to show determines how much salt to sprinkle. It might be best to use a little bit more than you think, as salt crystals are very small. The salt will basically glue itself to the model when it is mixed with a tiny amount of water. Let this dry overnight.
6. Spray on your topcoat over the model and areas where you applied your salt to and let dry at least 24 hours.
7. Once everything is dry, either with your fingertip or a flat toothpick brush the salt off your model. Sometimes the salt can stick a little bit, so apply just a little bit more pressure to pull it off. Depending on how much you put on, it should only take a few minutes to pull off. As you pull the salt off, you will see the bottom coat start to show through. Now you are done with the weathering. Essentially, what you have done is recreate the exact process of paint chipping.
Steps for creating digital camouflage on figures
1. Salt is the perfect tool for creating this new, difficult to paint pattern. It is a cubic crystal, which makes it great for creating the cubic digital camouflage patterns. Rather than spend hours gently dabbing on microscopic dots that will drive you crazy, you can have this done in a couple minutes over a few days.
2. All steps are the same as weathering with salt. However, there a few things that needs to be done slightly different. Think of painting the new Marine Corps MARPAT woodland camouflage pattern. There are three primary colors and one secondary color: black, brown, buff, and green.
3. In step 3, make sure the bottom coat is your darkest coat. Using the example of the MARPAT pattern, this would be black.
4. Repeat steps 3-5 with each subsequently lighter color – brown, buff and green. Make sure that green is the final coat. You will be adding a lot of salt over time, so brush it on gently in order to not soften and remove the previous layers. You will have three layers of salt and four layers of paint when finished.
5. Follow step 7 and remove all the salt. What you are left with is the new digital camouflage pattern. Quick and easy. This process can be repeated with any of the new camo patterns, desert, gray, blues, etc. Always start with your dark bottom coat and use the next lighter color at each subsequent step.
Haven't tried it myself yet, but Good luck!
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