How to Make Milk Paint

A couple of recipes, the main difference is one uses lemons, the other limes hydrated lime or slacked lime, another recipe used limes.  

(MARTHA STEWART)

MATERIALS 

Lemon

1 quart skim milk

Sieve

Cheesecloth

Dry color pigment or artists' acrylic paint

STEPS

STEP 1

Mix the juice of a lemon with 1 quart of skim milk in a large bowl. Leave the mixture overnight at room temperature to induce curdling.

STEP 2

Pour it through a sieve lined with cheesecloth to separate the solid curds from the liquid whey. Add 4 tablespoons of dry color pigment (available at art-supply stores) to the curd; be sure to wear a mask, and stir until the pigment is evenly dispersed. Artists' acrylic paint also can be used in place of powdered pigment.

STEP 3

Add it one drop at a time, and stir constantly until you achieve the desired hue. Whether pigment- or acrylic-based, milk paint will spoil quickly, so it should be applied within a few hours of mixing. Rest assured, its sour smell will disappear once the paint dries. 

http://www.marthastewart.com/272306/milk-paint-recipe

Real Milk Paint.com

http://www.realmilkpaint.com/recipe.html

1870 Milk Paint Formula

1 Quart skim milk (room temperature)
1 Ounce of hydrated lime by weight
(Available at building centers. Do not use quick lime, as it will react with the water and heat up. Hydrated lime has been soaked in water then dried.)
1 to 2 1/2 pounds of chalk may also be added as a filler.

Stir in enough skim milk to hydrated lime to make a cream. Add balance of skim milk. Now add sufficient amount of powder pigment to desired color and consistency (Pigment powder must be limeproof). Stir in well for a few minutes before using. For best results continue to stir throughout use. Apply milk paint with a cheap natural bristle brush. Allow project to dry sufficiently before applying next coat. Extra paint may be kept for several days in the refrigerator, until the milk sours. Double or triple the recipe for paint. Allow to dry thoroughly 3-4 hours before use. For extra protection, give paint a coat of oil finish or sealer. Color may change - test in inconspicuous area.

Very Durable Weather Resistant Paint

5 parts cottage cheese or dry curd cheese
(Dry curd cheese is cottage cheese without cream or flavoring added. You can make a similar cheese by putting cottage cheese into cheesecloth and hanging it until it stops draining. Use cottage cheese if you’re in a hurry.)
1 part hydrated lime or slacked lime

Mix hydrated lime with water to make a paste. Add to cottage cheese and stir in well. Leave for few hours - the cheese lump will dissolve completely. Select some powder pigments and add to solution (Pigment powder must be lime proof). Add more water if too thick; powdered skim milk if too thin. Strain if you want a fine paint (old nylon stocking works well).