Here is a great recipe for making milk paint from locally bought materials (as in your local supermarket and hardware store).
Milk Paint is an amazing alternative to store bought paint. It is much lower in energy since the ingredients require much less processing. It is also pretty much free of any harmful toxins. We painted most of the Brooklyn Green Show House with milk paint.
We got ours from MilkPaint.com. It costs about the same as a high quality store bought paint, which is on the high side. The good thing is that it goes on thick so you don’t need primer. One coat will do. The bad news is that it is matte and so can dirty easily if you have grubby little kids’ hands. We remedied that by putting a sealer over it, which forgoes the convenience of a single coat of paint.
If we were to do it again we would try to mix our own milk paint and add some more shine to it so it is more resistant to kids paws.
Below is an email I got from a fellow green builder from Canada, John Salmen, who offers some good insights into milk paint and gives a great recipe.
The thing with paint is that it is like bread – you can buy it from the store or you can make it.
The problem we have had is that once you make your own paint and have that on your walls it is hard to simply go to the store and buy paint. I am only saying that as we are having to repaint some rooms and I am loathing the work involved in making and brushing on the paint and I kind of wish I could simply accept the looks, smell and toxicity of regular paint.
If you do get inspired to make your own here is a basic home recipe that can work on bare drywall for a simple milk paint that works with better coverage than most commercial milk paint recipes. I first developed it when my son wanted to help paint (at about 2) so I wanted something that was friendly and that my dog could eat. He is now 15 and the basic paint (or a variant) has been used in numerous homes since by demand (I’m not in the paint business and it has been a pain).
It has to be applied by brush and has a relatively coarse texture very similar to earthen clay finishes. I have a more sophisticated recipe at this point that uses casein but this amounts to the same thing with ingredients that are readily available.
Skim milk powder -12 cups
calcium carbonate (basic chalk) -6 cups
lime -6 cups
kaolin (clay) -5 cups
* detergent (dry – non additive laundry type) -1 cup
colourant (davis concrete pigments or stucco pigment – try not to exceed ¼ cup)
7 cups water.
Mix the ingredients dry as accurately as possible and mix well (important) and then add about ¾ of the liquid mixing with a paint mixer on a drill or even a hand blender. Will be quite thick but you then have to let it sit (hour or so) for the clay to slake a little (absorb liquid) and then mix some more and add the remaining liquid (add more liquid if needed).
It needs to be a relatively thick mix (pea soup- gelatinous type of thing) to brush effectively. The liquid mix can be kept for a few days (refrigerated) if it smells sour discard. This is time consuming to paint as the brushing needs to be done in a very ‘craftspersonlike’ manner to get good results. Use a cheap bristle (stain) brush.
Can get the basic clay from potters supply. Lime and calcium carbonate from agricultural supply. Large bags but inexpensive – works out to a few dollars per gallon.
I usually substitute a sodium silicate solution for the liquid (waterglass). It is usually sold as a concrete hardener in 5gal pails. Increases the hardness of the surface and can provide a little better water resistance.
Paint can be temperamental i.e. if the wall temperature is too high (around light bulbs and heaters) the reaction can result in flaking. Other than that it results in a very hard finish. Will water spot if sprayed but generally can be wiped for most marks).
* Note regarding the detergent:
Actually borax works in the solution instead – it is usually an ingredient in a ‘pure laundry detergent’. The detergent is added as a generic surfactant which helps the ingredients mix and keeps them in suspension. Typically anything that is classified as a pure laundry detergent will work.