Milk of Human Purblindness

Over the weekend I received a flurry of emails from readers wishing to know the brand and colour of milk paint I used on a pair of forest chairs I made last year. I suppose it had to happen one day.

I know, I know, proper milk paint (milk, slaked lime and pigment) has been identified in a number of ancient Egyptian tombs, but it doesn’t follow that it was ever used on seventeenth-, eighteenth- or nineteenth-century furniture. It simply wasn’t! It was far too fugacious.

Seventeenth-, eighteenth- and nineteenth-century house painters applied distemper to the walls of buildings, (which at least employed animal glue as a fixative), but even with its usual top coat of varnish, it too was not sufficiently hardwearing to be considered of any use on furniture.  Imagine the slimy, sticky mess that would result from a distemper-painted forest chair becoming wet.

Of course, the most suitable paint for indoor and outdoor furniture that was both hardwearing and water resistant, was oil-based. North American paint Analyst, Susan Buck, scrutinised many items of Shaker furniture and concluded:

The physical evidence makes plain that the Shakers generally used traditional oil-based paints to paint wooden objects and architectural elements, and recipes containing milk are primarily lime-based whitewashes or exterior paints, not furniture or interior paints.[1]

(Confusingly, Australia’s Porter’s Original Paints states, “Porter’s Milk Paint is a traditional finish, first used in the 18th and 19th centuries on Shaker furniture.”)

British forest chairs were likewise painted with oil paint. The Gillows archives mention sending green paint abroad with a sea captain for the purpose of painting their cargo of chairs upon arrival at their destination in Antigua. By the duration of such a sea voyage, one can confidently conclude the paint was not milk paint!

If you are quite determined to paint woodwork with milk, at least add it in conjunction with oil in a traditional style emulsion paint. Emulsion paint is still far from ideal, but is what the majority of (now faded and flaky) wooden farm implements and machinery was painted with.

Henry Baird published the good oil on ‘milk’ (lime/milk/oil emulsion) paint for architectural work:

In consequence of the injury which has often resulted to sick and weakly persons from the smell of common [oil-based] paint, the following method of painting with milk has been adopted by some workmen, which, for the interior of buildings, besides being as free as distemper from any offensive odour, is said to be nearly equal to oil-painting in body and durability.

Take half a gallon of skimmed milk, six ounces of lime newly slaked,* four ounces of poppy, linseed, or nut-oil, and three pounds of Spanish white. Put the lime into an earthen vessel or clean bucket, and having poured on it a sufficient quantity of milk to make it about the thickness of cream, add the oil in small quantities at a time, stirring the mixture with a wooden spatula. Then put in the rest of the milk, and afterwards the Spanish white.

It is, in general, indifferent which of the oils above-mentioned you use; but, for a pure white [paint], oil of poppy is the best.

The oil in this composition, being dissolved by the lime, wholly disappears; and, uniting with the whole of the other ingredients, forms a kind of calcareous soap.

In putting in the Spanish white, you must be careful that it is finely powdered and strewed gently over the surface of the mixture. It then, by degrees, imbibes the liquid and sinks to the bottom.

Milk skimmed in summer is often found to be curdled; but this is of no consequence in the present preparation, as its combining with the lime soon restores it to its fluid state. But it must on no account be sour; because, in that case, it would, by uniting with the lime, form an earthy salt, which could not resist any degree of dampness in the air.

Milk paint may likewise be used for out-door objects by adding to the ingredients before-mentioned two ounces each more of oil and slaked lime, and two ounces of Burgundy pitch. The pitch should be put into the oil that is to be added to the milk and lime, and dissolved by a gentle heat. In cold weather, the milk and lime must be warmed, to prevent the pitch from cooling too suddenly, and to enable it to unite more readily with the milk and lime.

Time only can prove how far this mode of painting is to be compared, for durability, with that in oil; for the shrinking to which coatings of paint are subject depends, in great measure, upon the nature and seasoning of the wood.

The milk paint used for in-door work dries in about an hour; and the oil which is employed in preparing it entirely loses its smell in the soapy state to which it is reduced by its union with the lime. One coating will be sufficient for places that are already covered with any colour, unless the latter penetrate through it and produce spots. One coat will likewise suffice, in general, for ceilings and staircases; two will be necessary for new wood.

Milk-painting may be coloured, like every other in distemper, by means of the different colouring substances employed in common painting. The quantity I have given in the receipt will be sufficient for one coat to a surface of about twenty-five square yards.

* Lime is slaked by dipping it into water, then taking the pieces out immediately and allowing them to slake in the open air. [2]

I’ll let second-generation paint specialist and historic paint consultant, Patrick Baty, have the final say:

To believe that [true] milk paint might in any way be more efficient than the more noxious conventional lead paint of the past is fantasy.[3]

Jack Plane

[1] Patrick Baty, The Anatomy of Colour – The story of Heritage Paints and Pigments, Thames & Hudson Ltd., London, 2017, p. 41.

[2] Henry C. Baird, The Painter, Gilder, and Varnisher’s Companion, Philadelphia, 1850, p. 97.

[3] Patrick Baty, The Anatomy of Colour – The story of Heritage Paints and Pigments, Thames & Hudson Ltd., London, 2017, p. 41.

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