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Two Layer Milk Paint

Here is a method for producing a durable, weather resistant, and lovely milk paint. The secret is PH. Anionic and Cationic layers will cross link and draw to each other.
Since wood is acid, first you start with the base coating. Alkali will tend to draw in and bond to acid. Then when the alkali coating is almost dry, add the acidic coating. The alkali coating and the acid coating will combine strongly, create fairly stable salts, and cause casine, the protein in milk that is the basis of milk paint, to cross link into a durable finish.

Don’t use whole milk, To much milk fat tends to go a bit rancid. This can leave a long lasting, unclean scent. Take 2% milk right from the carton or use powdered milk mixed just as the recipe calls for. Dissolve as much borax into the milk as it will hold. Just like adding sugar to ice tea, you hit a point where crystals collects at the bottom and won’t dissolve. That means the fluid has as much as it will hold. Add a touch more milk stirring until the last of the borax crystals dissolve. Otherwise the borax crystals can give a gritty feel to the surface. The grit can be nice in it’s own way but is not what I am usually trying for.

This treatment makes a great first layer. borax is a very strong anti fungal, insect preventing, antioxidant layer. It is used in industry for all three reasons. In low levels it is also good for plants, so a bit of leakage is not likely to cause environmental issues. If you want to be serious about preservation, soak the wood.

Here is where some adjustment for effect can be made. The plain borax/milk mix will be slightly yellowish white but mostly clear. If you mix in more powdered milk, you will get a stronger antique yellow look. You can substitute builders or masons lime for borax if you want a more opaque, white appearance. If you go with lime entirely, you make classic white wash. A thin white wash will still allow grain to show through. If you want a chipped paint look, thicken the mix with builders or masons lime. A thin paste will crack when it dries and give a rustic chipped surface. Extra agricultural crushed limestone can give an old paint type bone dry finish. If you want a quality white coverage, add titanium dioxide.

Let the first layer almost dry. Then paint or rub on the second coat. This coat is acidic so it will bond and cross link with the first layer.

Add frozen apple juice to more 2% or powdered milk. As you add it, first the milk will curdle, as you add more apple juice concentrate, the milk will uncurdle. When it is fully uncurldled then you have added enough apple juice.

One of my favorite mixtures is powdered milk diluted by room temperature apple juice concentrate. I keep adding milk until it starts to curdle. Then I add a bit more apple juice concentrate to get rid of the curdle. This makes a hard antique yellow coating.

Take serious heed of this warning, Apple juice while being near harmless internally is a very very strong acid. In particular it is very good at breaking down skin. Many plastic gloves will not last long if you are using apple juice.


Concentrated apple juice varies at about PH 2.3 and It can be much stronger. Even diluted it can be quite caustic to skin if it is ignored. I use heavy duty chemical resistant gloves and a lab apron when working with this paint. If it gets on your skin or gets your clothing wet, clean it or change immediately. I did not, and the injury was quite severe.

If you want a nice green color, add some copper sulfate. This will start out blue but will turn into verdigris (Copper Green) and be totally light stable. Copper sulfate is also acidic, so it goes well in this layer. It also protects strongly from insect damage and is often used agriculturally.

Be careful with the copper sulfate, later it will be fine, but while mixing and applying it is a bad chemical to expose your nose, lungs, eyes, mouth and skin to.

It is also good at this point to mix in some oil. Oil will help bond in the borax, and also help preserve and give a good feel to the wood. Oil will also alter the manner that the casein (the protein in milk that makes it a great paint) cross links and will make the casein more flexible and resilient.

Boiled linseed oil is good, but can grow mildew. Linseed oil will also tend to yellow with time. Tung is superb. Safflower will give the clearest color, but you need the right type of Safflower oil. High Linoleic Acid Safflower oil is a superb drying oil and is used in quality oil paints. Most cooking safflower oil is the other type.

Adding oil will help prevent the borax from leeching out and also help preserve the wood. A bit of oil also gives a good feel to the wood. Oil will alter the manner that the casein cross links and will make the casein more flexible and resilient. Don’t worry that the oil does not mix, stir it well and rub it in. I try to pour just enough oil to just cover the surface of the paint.

After a while the oil may mix into it as an emulsion, otherwise, your rag will tend to pick up both oil and milk. Since I will probably come back later and oil it once more, I keep enough oil on the surface, regularly mixing it in, to cover. You will probably have to add more oil as you go. Without the oil, you get a very dry and flat appearance. Nice in it’s own way but not always what I want.

Too much oil and no milk goes into the mix. You can coat with an oil free coating and then rub in oil before the milk is dry. I just like the feel and convenience of both together. The rag will hold up better with oil in it. I like to wipe it on with a rag and then rub it in like you would polish a car.

I rub in the coating with a square ripped from an old towel. I throw away the old towel after doing this layer, and wash all my equipment immediately after I am done. It is easy to wash immediately but if you wait, it can be very hard to clean up. The towel may have to be replaced part way through your work as the apple juice may destroy it. More oil gives satin finish, no oil gives a chalk flat finish.

Making the first layer light colored, and making the second layer darker but thin, gives an appearance of richness and depth. To color this paint, use pigment powders such as the ones used in ceramics. Apart from the very light colors such as yellow and white, a small amount of pigment will go a very long way.

This is also a quality treatment for leather.

This stuff is the cheapest paint you will ever use. Take some scraps, label them with a sharpie, and make some small batches for experiments. At an agricultural supply 50 lbs of lime will be under $10, while you are there get the copper sulfate for less than a can of good paint. At the grocery store, a jug of milk, a box of powdered milk, a few cans of apple juice, and a box of borax won’t set you back too far. Get this stuff and play with it as you wait for your pigment order to come in. Talk to the folks at the pigment place, they are usually quite a good resource.

There are quite a few examples of milk paint remaining from prehistoric times.  In my local downtown, there are still Saloon signs, painted on the old bricks, that can be clearly read from the train tracks, these were made with milk paint.  This is a paint that, if done well, can survive drastic change.

Bob

33 comments to Two Layer Milk Paint

  • philclip

    Merci, merci beaucoup!!!
    Thanks for this recipe. I am French and I find THE recipe of “milk paint”.
    I try to tranlate your text and, perhaps, i will ask you some question…
    Philippe Clipet

  • You are quite welcome, Philippe!

    Up in the top left corner, I have a set of flags that can be clicked on to translate this page. Sadly it appears to translate only the main page, so older articles are not as language friendly. It is possible to translate using translate.google.com

    Bob

  • Skip J.

    Good to see you in here Philippe!

    I did 3 plus years at Sherwin Williams in the late ’60′s and the idea that an oldie could come back with advantages over the new formulas is very appealing!

    Skip

  • philclip

    Thank you both. The best recipe (for me) French milk paint is that of Mr. Cadet Vaux in the early 1800:
    is mixed with 1 litre of skimmed milk 200 grams of lime; adds gently on 130 grams of linseed oil, or œillette and tally of 2.5 kg and a new litre of milk.
    See you read.
    Phil

  • Skip J.

    Thanks Phil!

    That’s cool…

    Skip

  • philclip

    Sorry for my English, it is dramatic (thank you Google).
    I think the American furniture painted with milk paint are magnificent. My goal is to reach your level of quality. It is perhaps with apple juice because it is the first time I see that ingredient in a recipe.
    When I understood your recipe, I will ask you to validate. We hope you’re ok, thank you.
    Phil

  • Tom C.

    #1
    When I mix the borax into the milk I do not get any color change at all and the result doesn’t show on wood any more than water would. I feel that I am missing a step somewhere but I have followed the article closely.
    #2
    Does the milk and apple juice (or vinager) need to be warmed to create a curd? And again, I see no yellow color. What am I missing? Help please.

    Tom

  • I purchased a bag of powdered agricultural, milk for calves. Some powdered milk is very white, some has a yellow tinge to it. The agricultural grade, and the human grade that I got at the store have mostly had a yellow tinge, but one package I got was pure white. Usually the more expensive stuff is less yellow, I am going cheap so usually I will get a yellow tinge to mine.

    If you add apple juice to milk powder, you tend to not have it curdle at all. If you add apple juice to milk, it will curdle until you add enough apple juice to raise the acidity to the point where the curdles dissolve.
    With exposure to sun, the white milk will probably yellow a bit, but I have seen’ milk paint on exposed brick, from just after the civil war era, that is still quite white.

    Because we are using organic and low processed materials, it is likely that there will be variations in appearance. I think this is the reason we have gotten away from these methods. I rather like the natural variations, so I think it is quite worth it.

    Bob

  • vi

    i would like to milk paint my studio walls, which are old plywood paneling from like the 70′s or so, plus the woodwork which is really old millwork that is finished in real shellac! (that could be as old as the 50′s!)
    what prep would i have to do? could i just sand it well? i don’t want to TSP it.
    and (yet another question) how about behind the woodstove? we have shields etc but there is a paneled wall behind the woodstove, how flamable is milk paint (i would imagine less then oil paint)

  • Bob Strawn

    Milk paint is based on casein, a protein, so it will burn, but not like oils will. Adding borax or boric acid to the mix will certainly reduce flammability. Since milk paint is so cheap, I would advise you to paint something and put it near the stove to test and see. I would personally be tempted to keep the trim treated with shellac. The real stuff is kind of fun to work.

    I would also test to see if the Milk paint will do on the wall without treatment. It probably will if you rub it in, but painting it might not have as good a result.

    Bob

  • Skip J.

    Hey Bob;

    Can you expand on the shellac part a bit????? I personally have found a whole new world open up over the last 5 years or so since I have been buying shellac flakes in different colors and denatured alcohol by the gallon.

    I never thought of using it on natural household woodwork surfaces tho…. all ours are just painted.

    Sorry, didn’t mean to hijack here… just couldn’t help myself…

    Skip

  • Bob Strawn

    Shellac from flakes has the downside that you have to wait for it to mix and then you have to use it all up before too long. It is also a bad surface for objects that will be exposed to alcohol. So your bar table is better off with epoxy.

    But for any smooth wood surface shellac is pretty easy to maintain, clean up and even restore. I am not an expert on shellac, but I rather like it. It also can make for a nice glossy surface without looking cheap.

    Bob

  • Skip J.

    Mmmmmmm, yes I can see that. Don’t have a bar in my house tho…. go figure…

    For ww’ing projects I can “build on” a new thin coat many times in one day; and have it harden up by the next day. A tremendous advantage over oils that I have used for decades. I can do 3 quickiee thin coats in an hour, and start waxing with your Olde Tyme Wax Mix the next day. By the way, I’ve used up the can and now need to get the hotplate down and mix my own. Good stuff!

    Back to the house trim – trying to think of natural wood showing in our all-paint surburban box is interesting…. a whole ‘nother subject. I could put flakes in a gallon of d. alcohol and stir it up every day for a week. Hmmmmm…

    Skip

  • Laurence N.

    Hi Bob,
    Thank you for the recipe. It is very helpful and more detailed and personal than other recipes that I found on the web.
    I have a preference for the dry and flat look (the no oil option) and was hoping you could recommend a natural and affordable homemade sealer to protect the paint job.
    Many thanks,
    Laurence

  • Bob Strawn

    Properly done, milk paint is generally longer lasting and tougher than the material it is painted on. Preserving the material is probably more important than preserving the paint in this case.

    Bob

  • Stig Taube

    Bob,

    Do you know anything about refinnishing your milkpaint?
    If it is not bare wood and so on?

    Stig.

  • Bob Strawn

    The only solvent I know of for milk paint is meat tenderizer. This works OK for single layer milk paint. Not so great for two layer. Well done two layer is really tough stuff. I am not sure that meat tenderizer is a good thing to soak into wood however. I have not done any testing.

    If you sand first, you should be able to bond on another layer of milk paint, or other paint. I base this on my front porch and steps. I put milk paint on my steps, and I have renewed it without problem.

    Bob

  • Thanks for the vaulable tips, Bob! I’m using milk paint for a portrait and I have been using techniques that involve glazes and a lot of layering. I’ve been layering Quark and oil with a beer glaze. . . some of the layers peeled, Doh! but I’m still experimenting.

    I love the milk and borax idea! I think it will make all the difference in the world to my layering techniques. I’ve been looking for a totally clear binder, too. I had been thinking of experimenting with borax and milk.

    Out of curiousity, do you think borax and milk would alternate well with a beer glaze?

    Thanks so much!

  • El Dris

    TSP or Trisodium phosphate will help remove old milk paint, its still a tough job and wear gloves!

  • Deborah Hining

    I had a problem with the batch for the second coat. Are you supposed to use dry milk powder and add apple juice concentrate? I used 2% milk, and it never curdled. It got a little thick, then thin again. When I rubbed it on over the first coat, which felt dry, it lifted off some of the first coat. Both the first and second coat formulas were really really thin, and the first coat just ran everywhere. I put on a second round of the first coat formula and it thickened up.

    Can you paint over finished wood? I added acrylic paint for color. It seemed to work for the first coat but curdled up in the second formula and never really dissolved.

    Thank you!

  • Bob Strawn

    I have no experience with using acrylic mixed with milk paint. I have been sticking with pigments that have high stability in acid and alkali environments.

    Milk paint can be quite thin when compared to conventional paints. Mixing oil in can make it into a bit of a thicker emulsion, but that is also something that can be inconsistent and needs a bit of feel for it. The best way to thicken milk paint when using powdered milk, is to put in more powdered milk.

    Bob

  • E.F. Lavender

    Thanks for posting this formula. To test the formula, I used it to paint some chicken nesting boxes and the finish came out quite nice.

    Your comment about a little pigment going a long way is right on the money. I used 1 tablespoon of Sakrete concrete pigment (powdered) in the first part of the formula. The hue was comparable to some other formulas on the web which called for three times as much pigment.

    For the second part, I dissolved the powdered milk in the apple juice concentrate, but it never curdled, no matter how much apple juice was added. When it reached the consistency of a latex paint, I stopped adding powdered milk or apple juice concentrate.

    I applied the second part of the finish as directed. When it was dry, I rubbed it down with an abrasive pad and rubbed on some tung oil. The resulting finish made the nesting boxes look like they were made from weathered red barn wood.

    Thanks again!

  • Annie

    Great post about milk paint!!! Thanks so much!

    I have 3 questions: about how much Borax will one need per gallon of skim milk? I mean, are we looking at a whole box, or a couple of cups?

    Same for frozen apple juice.

    And finally, why do you use apple juice instead of vinegar, which has a regulated acidity of 2.3? Just curious.

    Thanks again :D Excellent information!

  • Jo

    Hi Bob, Thank you for posting this information. I have a couple of questions I hope you wouldn’t mind answering. Re the concentrated apple juice, will a generic off the shelf carton of juice suffice or should it be of the homemade variety? Why frozen apple juice? Can I use earth pigments with this recipe? Finally, when you say ‘Mak[e]… the first layer light coloured, and mak[e]… the second layer darker..’ do you mean add some pigment to layer 1 or apply two layers of layer 2? Regards, Jo.

  • Bob Strawn

    A box of borax will go for quite a few gallons of milk. Earth pigments are stable, the ones I have used were from a company that supplies them for pottery, so they are more likely to be tested and stable than the ones provided for painting. Usually there is no difference until you get to the green and blue shades. A small batch of this stuff can be mixed in a cup and tested in a day. For the real test, years and weather may be needed, but this method is a simple framework, more than a formula, to make your own unique paint. Play around with it!

    In retrospect the vinegar is worth trying. At the time, I was also looking for added nitrogen while keeping a good percent acidity.

    Bob

  • Bob Strawn

    My first layer is usually alkaline by way of lime, so having be light is easy. My second layer is acidic so adding iron or copper sulphate would work fine to make a translucent but darker layer. If a more striking effect is desired pigments such as titanium white could be added to the light layer and earth shade pigments and the like could be added to the top layer. The fun part is that it is cheap and easy to play around and make your own unique yet classic finish.

    Bob

  • Frank

    Hi Bob,
    Great information thanks for posting all this.
    I like that your recipes seem to be mix it and go. Some other recipes involve allowing non fat milk to curdle over night and then strain the quark. Can you comment on the differences and also why you use 2% vs 1% or non fat?

    I am looking to paint the interior and exterior of my house with some form of milk paint as I have become hyper sensitive to traditional paints and cannot go near them until fully cured. I am looking forward to painting again. And this looks like the answer!

  • Bob Strawn

    Since powdered milk works fine, 1% would probably do fine. 2% from my own experience has not shown much tendency to rancidity, so I will continue with using 2%. If painting wood, you need flexibility in your paint. Wood changes dimensions with the weather. Leaving a touch of oil or fat in the original mix will tend to allow elasticity to remain. I add a drying oil to my mixtures, but having a bit of fat suspended in the original composition does not hurt and seems to improve the suspension quality of adding other oils.

    Bob

  • Bob Strawn

    Being of Scottish decent, I doubt I will ever experiment with beer mixed in my paint. Beer is sometimes involved when I am painting, but it goes into me and not the paint. ;)

    Bob

  • Frank

    Thanks Bob. Do you have a recipe for house painting?

  • Bob Strawn

    Not so far.

    Bob

  • Dick

    Bob
    You mention adding oil several places, are you refering to linseed oil/tung oil or something else? I assume you are not refering to a petroleum oil?
    Thanks
    Dick

  • Bob Strawn

    I use safflower oil. There are two types of oil you can get from safflower. On is from the main genetic line of the plant. It is called High Linoleic Acid safflower oil. This is the stuff I use. There is a common enough mutation grown that may be mixed in or selected that is not the same. What I do to be sure it is the right stuff, is first look on the nutritional label. If the nutritional label has Polyunsaturated fat as a much higher number than Monounsaturated fat then it is probably the right stuff. The problem is that the sources can change for seeds and crops leaving us with less data than we think we have. When I get a bottle, I open it and then soak a bit into a paper towel and put the paper towel under the bottle. The bottle is left with the cap loose where the sun can reach it. This way, the oil will transform into stand oil. After two weeks, I check the paper towel. if the oil has turned to a rubbery resin, it is the right stuff! If not, it is still good oil for treating wood, but it is not good oil for making a finish. Use it like mineral oil, but not like tung or linseed oil.

    I use High Linoleic Acid safflower oil. instead of BLO for just about everything. is a superb drying oil and is used in quality oil paints. It does not tend to mildew or yellow. It dries slower, but you can instant dry it by heating it carefully over a burner. I treat wooden tools with the wax mix and quick cure the surface over a burner as well.

    I keep a wax mix made with this oil handy all the time. This link, http://toolmakingart.com/2008/08/06/wax-mix/ Will give you more specifics on how I make my wax mix.

    Bob

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