Making milk paint by the gallon to paint my garage remodel!

I've made milk paint before, but always only processing 1/2 gallon at a time, which results in about a quart of milk paint. I used it to paint signs and for kids to use in the forest school we're part of, as well as for kids to paint doll-house-sided wattle and daub houses in the history class I taught. I thought it was time to up my game, and make gallons of milk paint!

Making gallons of milk paint comes with its own problems, though. These are the ones we encountered while scaling up the milk-paint production to paint a 400sqft room:

How do you curdle that much milk at once?

How do you rinse and drain that many gallons of curds?

How do you make sure you make the paint a consistant color each time?

How do you make sure you mix the paint well enough?

Will it stick to drywall mud?

Will it stick to latex paint? What if we use a binder?

I'll try and answer them one at a time.

How do you curdle that much milk at once?

There's a few ways. If you have time and planning, you can make one or two batches a day, and just store the curds in a big container in the fridge. They will store for at least 2 weeks as just curds in there.

1/2 gallon of skim milk treated with vinegar

Straining it with an old cloth diaper in a large strainer over a pot.

But, that takes a lot of advance planning! If you just want to start painting the next day, you can pour gallons of milk into 5 gallon buckets, add the vinegar, and cover over night.

How do you rinse and drain that many gallons of curds?

If you do this in small batches, it's easy. But, if you're doing gallons at a time, it gets tricky!

We did not have enough strainers or large enough cloths to strain through. Because of this, we strained the curds in batches. It's important to have enough cheese cloth (or old flat diapers, or paint bags, or other thinnish material that liquid can seep out of). We found that we could pour an amount of curds into the cloth on the strainer, then tie the bag and hang it to drain under a tree. Then we would put another cloth and fill it full of curds, rinse them with the hose (on "shower," not "jet"! Jet pulverized the curds), and then hang them under the tree.

Our two stainers, propped up by bricks. Behind is the buckets we had the skim milk in before we poured it off

Four gallons of milk results in about 4 cloth diapers full of curds to hang to dry. We already cut down two bags by the time I took this picture.

Be careful when filling and tying your bags of curds! The curds really want to spill out the sides. Make sure to get every corner and edge of the cloth bundled to the top and tied with string. It helps to not over-fill the cloth!

How do you make sure you make the paint a consistant color each time? and How do you make sure you mix the paint well enough?

If you have scales and like to weigh things, that's probably the best way to go. We used cups and measuring spoons. I made sure to always use the same measuring cups/spoons for each material, and to always pack them flat.

I also found it was a LOT better to mix all the dry pigments in one bucket, and mix the milk and lime in a separate bucket. It's kind of like baking. Mix dry ingredients in one bucket, and wet ingredients in another bucket, and then slowly add the dry ingredients to the wet ones, just like when making a cake.

This was the WRONG way. I put in the curds, then the pigments, and then the lime. It did not mix completely!

This did not work. It was very clumpy and a lot of pigment stayed stubbornly at the bottom and sides!

Because we did not mix that first batch well enough, when we mixed our second batch of paint, it came out MUCH lighter...even though we added the exact same amount of pigments!

Because our first batch was not mixed well enough, it was quite a few shades darker than the next batches! You can see it here on this partially painted wall

To mix the next batches better, we tried a few things. First, we tried using a manual egg beater. This worked, but was very tiring, and only did one gallon at a time! Then we tried using a stick. This worked, but slowely, and our arms got really sore!

Finally, my husband decided to bend a coat hanger into a sort of whisk, and he attached that to our drill. That worked great!

Our coat-hanger mixer, no longer attached to the drill

We also found it helped to mix in a 5 gallon bucket. This reduced splashing and made it easier to add the dry ingredients bit by bit. It was surprising the amount of dry ingredients we added to the milk curds. Here's the recipe we used for our creamy off-white color:

Liquid Ingredients

- 6 cups of curds
- 1/4 cup hydrated lime

Dry Ingredients

- 5 cups of fine kaolin clay (I just used what I already had for spraying on my trees)
- 5 cups of calcium carbonate
- 1/4 cup clay brown
- 2 tbsp yellow ochre

It was basically a gallon of dry ingredients for 6 cups of curds. For a runnier paint, add another cup of milk curds and some more lime. For a thicker paint, do just 5 cups of milk curds.

Will it stick to drywall mud?

Yes it does! We used this joint compound. It took longer for the paint to dry around the drywall tape and mud, but it dried just fine.

Will it stick to latex paint? What if we use a binder?

I bought this milkpaint acrylic binder, but when I tested it on a small section of latex paint, I found it to be very streaky and hard to work with.

I thought I would try painting directly onto the latex paint. First, I washed the wall, and then we mudded parts of it, and then I painted. The paint stuck just fine!

Painting over drywall mud and blue latex paint. Note how dark and transparent the milk paint is when wet!

Here's the wall after one coat of milk paint. You can still see the blue faintly, but not very much.

One thing to note about painting with milkpaint that's made white with clay and chalk, is that it DOES NOT show it's true color when wet. At all! The white does not show up until it's dry. It's rather terrifying the first few times you do paint with it, because you're sure you just painted your walls a Spanish orange...and then it dries to a light peach!

Any other things to note?

Our cream paint was very thick. This made it go on well, and it has a mild texture. But, it was frustrating trying to paint the ceiling. As my husband said, "It's like painting with clay!" And, he's right! I find the texture similar to a high-quality, thick acrylic paint. But, we could have thinned it out more, too, by adding more milk (we actually did this for the second coat of paint on our ceiling, just to stretch the pigment we had on hand, and because the first coat was almost perfect coverage)

The milk-painted ceiling

This is so neat.

I've been putting off painting my bedroom because I don't want to move out for a month while the paint cures.  This might solve that issue.

Thanks for the inspiration.

As far as I can tell, the milk paint has applied to the latex paint just fine. I'm sure it's not quite as durable as if it were soaking into porous materials (like stone, wood, daub, cob, and drywall). But, I don't see any cracking and the paint went on fine.

Plus, once this paint has set up, it's generally a pain to get it off of things I want to get it off of, such as metal measuring cups and plastic buckets. Those are all non-porous, but the milk really does stick. I figure if it's a pain to get off of things I want it off of, it should stick on the things I want it on.

Making milk paint is more work than buying paint, but it's so nice to not need to worry about VOCs. It's also fun getting to customize the exact color you want! I hope you're able to give it a try--if you do, I'd love to know how it turns out!

---

Today I noticed that, despite taping with painters tape, one of my (metal) light fixtures got quite a thick coating of milk paint in places. It did not want to scrape off.

But, I thought about how so many ancient stone sculptures were worn away quickly by acid rain. Since limestone is the stuff that makes milk paint durable, and it's alkaline, I thought that maybe vinegar would take the paint off. It did!

So, if you get milk paint on something you don't want it on, try vinegar to clean it off!

And, if get dirt on your milkpaint walls, don't use vinegar to clean it off. You'll probably "clean" off your paint!

The paint is 30+years old, so we give it a good sanding before applying a new coat.  Perhaps more sanding would help it adhere?

Not sure if it's latex or oil or ?? based on the walls now, but the modern paints stick when sanded first.

I forgot, but we did end up sanding our latex wall. Since there were a lot of dings and bad taping done on it, we put a lot of drywall mud over it. Then my dad took a giant fancy sanding thing and sanded the whole wall. He was doing that to smooth out the drywall mud, but it also sanded the paint in the process!

I just realized I never updated this thread. The milkpaint on the walls turned out great. It's important to keep stirring it, because some pigments settle over time, and you end up with a slightly different color at the end as at the beginning (we didn't really notice the difference until we were at the very bottom of the bucket). We also kept out wall paint very thick, so that helped the paint not settle too much.

Part of the wall was made of concrete, and we painted that with the same color of creamy paint, and then I made "fictive masonry" (aka faux bricks) to look more like a medieval stone wall, rather than a weird section of color for no reason. I really like how it turned out!

We then mixed green viridian and yellow ochre pigments to make the floor, but we didn't have enough milk curds for two coats. So we had to make up another batch of curds, but they didn't want to drain as well (maybe because I used citric acid instead of vinegar to curdle the milk? I just don't know). We also were running low on pigment, so the paint ended up being rather runny. That's when we discovered that the paint really needs to be stirred, or the yellow ochre rises to the top. Worse still, if you put the runny paint down a bit too thick, the yellow ochre rises to the top and you get a yellower spot right there. No good!

Then the floor paint started cracking, but that's a story for another thread. If you have any idea why the paint started all chipping, or how to fix it, or what to do instead, I'm all ears!

I was asked about using milkpaint without pigments to paint the walls in their house that they're building. I wanted to post my reply here, too, in case someone else had the same question:

The milk paint, even though it has lime, doesn't make that opaque of a color. It's very thin and drippy, too. You could add either kaolin clay &/or calcium powder to the paint for more opacity. This is the calcium powder I used: Duda Energy Calcium Carbonate. It makes a nice chalky white. The kaolin clay is a bit more creamy, and it also makes the paint a lot thicker. Milk paint is usually quite runny, and the clay helps make it apply without too much dripping or coats.

Does it matter what type of milk is used (i.e. cow, goat, etc.)? Also could a plant based milk work?

Making curds in soy milk is how tofu starts out and I have used finely grounded almond flour to make tofu. Making almond milk is for me easy but making four or five gallons would take sometime.

From what I understand, it's the casein in the milk that acts as the "glue" that fixes the pigment (and lime) to the wall. Any milk without casein likely isn't going to work terribly well. I recall reading that some ancient cave painting might have been affixed with breast milk. Goat milk also has casein, so I would assume that it would work well, too. (I have no idea if A2 vs A1 casein makes a difference). I don't think plant-based milks have casein, so they probably won't work in the same way.

I don't know if other proteins will be sticky and strong in the same way that casein is. Gum arabic might help add to the stickiness of non-dairy milk paint, but I really haven't tested that much (I've only used small amounts of gum arabic with my pre-made milk paint powder from Real Milk paint when I wanted to use those pigments for painting watercolor pictures. It didn't seem to do anything negative, but I also only used it in tiny amounts).

Nicole Alderman wrote:(I have no idea if A2 vs A1 casein makes a difference). I don't think plant-based milks have casein, so they probably won't work in the same way.

I don't know if other proteins will be sticky and strong in the same way that casein is. Gum arabic might help add to the stickiness of non-dairy milk paint, but I really haven't tested that much (I've only used small amounts of gum arabic with my pre-made milk paint powder from Real Milk paint when I wanted to use those pigments for painting watercolor pictures. It didn't seem to do anything negative, but I also only used it in tiny amounts).

Casein, I think is only found in animal milk but there maybe a vegan form. I remember listening to a Paul Wheaton podcast and in it talking about uses of casein one of the uses was paint. I wonder if powder cows milk could be used to make paint? I think it would save space in the refrigerator.

Considering a lot of milk paint supplies sell powdered paints, I'm thinking powdered milk should work. But, it likely still has the whey, so you'd probably need to rehydrate it and add vinegar to curdle the milk and remove the whey.

Another option might be to buy something like cottage cheese or farmers cheese that has the whey mostly removed. It'd take up less space in the fridge and be more ready to use. It's probably more expensive, though!