You will need
- 250ml (1 cup) skim milk (it does matter, you want skim)
- 32ml vinegar
- 7g hydrated lime
- 16ml water
This recipe scales linearly. Need more paint? Double the batch
Excess paint can be stored in the fridge for at least three days.
Takes about 20mins all up if you’re not trying to video the whole thing.
Step 1: Preparing the Milk/cheese
- Add milk and vinegar to a saucepan, lightly mixing (but not more) the mix.
- Turn on the heat to a low setting, you dont’ want it above 46c or “until just a wisp of steam”
- Wait for ~5-10mins for the whey and the curds to separate. The whey around the edges should start going pretty clear
- Transfer the curds into a colander lined with doubled over cheesecloth.
Rinse the curds several times – you want any remaining vinegar to be cleaned off so it doesn't react later on.
Watch as your paint recipe disappears as your wife realises you’ve just made cheese
You can leave it at this stage in the fridge for awhile/until you're ready to make up the rest of the paint.
Step 2: Making the Paint
- Measure out and mix the lime and water in a separate container. Wear gloves for this part, hydrated lime isn't the greatest for you.
It doesn’t take too long for it to become a smooth paste.
- Add the curds into the lime paste, mix like crazy.
- For the smoothest paint possible strain through a stocking. Skip this step if you want it lumpy.
- In a separate container, mix up the oxide powder and water until its ‘all wetted’.
- Combine the wet oxide powder into the curd+lime mix, mix until smooth
- For the smoothest paint possible strain (again!) through a stocking. The oxide powder may have introduced new lumps
Done. Paint stuff. I used a synthetic bristle brush, washes out super easy.
Step 3: Bonus Round
You can also add a small amount of borax for antimicrobial properties.
You can use other things to add pigment, like universal tints, acrylic paints, probably food dye
We’re still experimenting with what works for us and is cheap.
If its going to be on a surface thats wiped down or exposed to moisture, I’d highly recommend applying a clear topcoat - any polyurethane would work, but sticking to a water based/acrylic coating will also dry fast and be lower in VoC's.
Step 4: Pricing
Milk paint is cheap. Stupid cheap.
- 1L milk is $1.
- 3kg hydrated lime is $8
- 1kg of oxide is $9.50
- Vinegar has some cost but the wife wont’ tell me
This makes anywhere from 700-800mL of paint. I’m sure my maths is wrong, but in dollary doos, its works out
1L Milk + 28g lime + 48g oxide = 1 + 0.074 + 0.456 = $1.53
We're finding we're getting about 1m^2 for 1L of paint coverage, though depending on your colour, you may need two coats.