Milk paint

Hi everybody,

I’ve just read an article about milk paint. It seems the have been around for a very long time (e.g.: shortly after the invention of cows).

Were harpsichords painted using milk paint or was it mostly oil-based paints (or other techniques)?



Known at least since ancient Egyptian times. It’s good stuff. You can make it yourself or buy it from many vendors nowadays. It’s incredibly tough and durable. It’s hard to get it off even with a blowtorch. And no VCO’s.

There have been conversations on the topic of milk paint on the older lists before. Owen Daly is a very experienced expert with it.

I don’t know which harpsichords were done with milk paint but I do know that a lot of 18c French furniture used it. It has the advantage that you can make lovely pastel colours that were popular in Rococo, and it’s very cheap - much cheaper than oils and such ingredients. Also, most house paints before the invention of acrylics were casein based milk paint.

On oil paint for harpsichords, I do know a little about this from speaking to a paint chemist with an interest in historical paints here in Melbourne. He pointed out that 17-18c oil paints were necessarily initially glossy, because the chemistry for matting them down was not known at that time, and the reason for many old instruments appearing to have matte oil finishes is that the oils and polymers have oxidized over long periods of time and lose their gloss.

Thanks Andrew,

The “non-toxic” part is very appealing. I found a video on YouTube where someone made a toy chest. His wife painted it using milk paint for that very specific reason: toddlers have the tendency to stick all kinds of stuff in their mouths, lick things, etc.

If, as an extra, it’s tough and durable than it’s definitely worth experimenting with it.



Le 19/04/2020 16:00, Chris Vandekerkhove via The Jackrail écrit :

If, as an extra, it’s tough and durable than it’s definitely worth experimenting with it.

If you make your own milk paint with casein and borax (casein isn’t
toxic, but borax is, by the way), you do have to put something over the
last coat if you want something durable, because it remains
water-soluble for years (or perhaps forever). Depending on how you look
at it, this can be seen as a disadvantage or an advantage. (One of the
advantages is that it doesn’t ruin your brushes, like so many other
paints, because it can be completely washed out.)

The best place to buy pigments (and casein, and borax, if you’re a
professional) in Europe is Kremer.

They also give Wehlte’s recipe for making your own milk paint.

Regarding the toxicity of borax, looking into this, it is very low. Borax is used in a lot of household cleaning and laundry products, and is even used as a food additive (though some countries ban it - nothing is simple!). It’s usage in household items has decreased over the last twenty years, but it is essentially not a harmful chemical.

I did synthetic organic chemistry at university, a very long time ago, so I do have some degree of understanding of chemistry. I checked a few chemistry databases regarding toxicity, and most agree it is pretty low. Exposure to the dust can cause respiratory irritation. So wear a mask when mixing. But exposure to many dusts can cause respiratory irritation, such as wood dust. You would have to actually ingest a large amount for signs of toxicity to occur. Of art and craft materials, borax would rate very low on the overall toxicity index. It is good for killing ants though!

I am increasingly dubious about the accuracy of information in Wikipedia as time goes on, but usually the articles on chemistry are pretty accurate. Here is what Wikipedia has to say about borax toxicity, which seems correct to me:

There are recipes for milk paint without borax, that use lime and lemon juice and so on. Since the idea is thousands of years old, there are a lot of ways to make it. Or you can buy it made up in powder from quite a few places in America.

Like all artists paints or other types, when using pigments from say Kremer, don’t overload the paint with pigment. You can’t get every colour in the spectrum to go well in milk paint. The heritage colours work best, and don’t expect to make really dark black.

These are some of the colours that are possible:

Some colour pigments are much more toxic than borax. Wear a mask.

Most people will put a clear top coat, or wax. But it’s interesting to know that over a long period of time the paint does become completely waterproof. That’s how houses with external milk paint retained their colour despite being rained upon for decades!

Also, milk paint works best on porous surfaces, and for that reason you can get binders to help it stick to less porous ones.

I was surprised to read this. When I was little we had borax powder and it was used very effectively for relieving the pain of mouth ulcers that I used to have. Perhaps together with the lead soldiers that I probably used to suck in those days, this may explain why I have the brain I have. :wink: :slight_smile:


Yes, I was at pains to point out it is very low toxicity. Boric acid however is very toxic. Perhaps that is a source of confusion.

I pointed out the toxicity of borax because this is the reason why you can’t purchase it in Europe if you’re not a “professional” - from Kremer or elsewhere. Nor will Kremer sell toxic pigments. I believe these are European regulations.

That would be due to spoil sport EU regulations. I am sure that you cannot now buy any of the photographic chemicals that iI could get from the local pharmacy as a boy in England, or the lethal inorganic acids that I could get on mail order in those days – and then there was the mercury I got from the dentist to play with… I told you about my brain! :grinning: