I've been experimenting with making my own interior and exterior non-VOC paint this week after reading about the durability of 9,000-year-old paintings found in Asia and Egypt.
I didn't have room for all of my findings in my weekly column (recipes included), so this is a little addendum.
Using concrete colourant, which is available at hardware stores, I tinted my first small batches of paint. I got some nice golds and reds (one coat).
Then I added a little titanium dioxide (available at pottery supply places for less $ than art supply places) to some of my skim milk/Borax base and got a beautiful 'pickling' stain, which I rubbed into a rustic cricket bench. The pigment built up in the rough texture (it's a little hard to see in the photo). This formulation would look great on an urban fence or deck.
Next, I used an exterior grade formulation made from cottage cheese and lime (which I learned about here) to coat this bench top (tinted with 'medium buff' concrete colourant). On the buttermilk-coloured legs and base I used a two-layer cross-linking alkaline/acid formulation that I learned about from this very smart person. (To get the warm colour on the legs/base, I tinted the acidic topcoat with titanium dioxide and a tiny bit of 'lemon yellow' concrete colourant.)
I literally did NO PREP on this bench - no brushing, scraping, or even wiping with a rag. Okay, I removed one old coccoon, but that's it. The bench had been outside for about 10 years and the original 5 coats of water-based urethane had flaked into oblivion. Note to self: never use water-based urethane for exterior applications; it can't hack the Canadian climate.
This is the bench after a borate-laced coat of casein (milk) paint, which I made from skim millk and Borax laundry additive.
After all of the experimenting, I think the milk/Borax formulation is the easiest to work with. It produces a clear matte finish on bare wood (bye bye forever water-based urethane) and can be tinted easily by making a paste of water and concrete colourant and then mixing it into the milk/Borax base.
You can make the milk/Borax stuff into an opaque white by adding lime and titanium dioxide till it's nice and thick.
Of course you can order milk paint powder from either of these two places if you don't want to go the wet 'n' wild route:
I'm aiming to paint 400 feet of fence with my own homemade milk paint later this fall. Anybody want to help?