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This recipe was sent to me a while ago by a reader. I do not know the source and I must admit that I have not tried it. Let me know how it turns out!
1 Cup Powdered Nonfat Milk
1 Cup Water
Powdered Paint Pigment
Mix milk powder and water first. Then add paint pigments (available at crafts stores) to color it, if desired. Too much pigment will lessen the durability of the paint.
This paint formula should dry to a somewhat glossy finish. To add durability you might want to spray it, once completely dry, with an acrylic finish.
There are now commercial milk paints that have additives such as lime and clay for better durability, workability and coverage. Be forewarned… they are also somewhat expensive compared with regular latex paints. Visit http://www.milkpaint.com for one such product.
I wouldn't add commercial paint to milk paint. Chemically speaking, you might affect the final finish and setting of the paint. Biologically speaking, if your desire is to use a less chemically-offensive product, adding an "unnatural" product to your milk paint just doesn't make sense.