Swedish paint and Potato paint questions

I was reading Permaculture Magazine issue 117 and read about using plain flour (Swedish paint) and a recipe using potatoes. The recipe for both of the paints looks to be just like cooking food. Have anyone used these paints? Could a person use a coffee filter to get a paint that could work with an air paint sprayer? What is a good pigment to use when just starting out?

I found this on;
Swedish paint recipe and instructions
'Boil 6.5 gallons of water.
To this add the Iron Sulfate or Zinc Sulfate, depending upon the color used, and stir until dissolved.
Add the rye flour*, cooking and stirring for 15 minutes.
Then add your pigment powder, stirring and cooking for another 15 minutes to create a homogeneous mixture.
Remove from heat and add linseed oil stirring well to create an emulsion.
Linseed oil should make up no more than about 8% of the total volume.
*Wheat flour may be substituted for the rye in this recipe, but may not possess the same strength.

Qualities: This is a matte paint that will dry in 2 hours and usually covers in one coat. Use only on rough, dry wood. It has a durability of 10 to 15 years with dark colors lasting longer than light ones.'