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Sealing casein distemper

Any experience or tips for large scale waxing, oiling or glazing over casein distempered walls to make them wipeable?

A reader has a 1730’s property and was talked into applying F&B casein distemper throughout almost the whole property. Some external plaster walls, fine, but also on studded and skimmed walls and ceilings too. :frowning:

He could re-coat with Classidur product, just thinking they could judiciously buff up the kitchen area and hallways to make the surfaces more practical.

I have used both techniques, wax and varnish. You can seal casein with varnish like polyvine acrylic dead flat which will not change the colour. Wax will probably darken the distemper. Both will seal the distemper,stopping it’s breathable qualities, unless you can find a breathable varnish. Perhaps an issue in a 1730’s property. If you do wax any later decorating will be a problem.

Thanks for that practical advice from the “coal face”.

Picking up on one point, I was speccing a job a while ago for sealing a mural on lime plaster and the upshot of it was that there is no such thing as a breathable wipeable varnish - you have to prioritise breathable or wipeable. I dont think he would encounter any issues waxing / varnishing over the distemper on new skimmed plasterboard walls!

The waxed surface could be overpainted with chalk paint quite easily, but as you say, when sealed, it is not breathable.

One breathable solution would be making a parchment size dries totally flat compatible with most distemper type products although not totally washable it would sponge quite well , or you could add some alum dissolved in hot water and added to the distemper will bind it far more than the farrow and ball binders. All their distempers to be honest are very poor .

How ever if farrow and ball had made a true casein distemper there would be no problem, casein is made from milk precipitated with acid. The casein is non soluble in water and is mixed with borax and lime. It is soluble in alkali. At that point water can be added once it has been applied the casein returns to its original state and being non soluble in water surprisingly becomes washable.

You can make your own. It is sold in powder form by most art shops. Add colour, hot water and you have a casein distemper. Better and far cheaper than f and b and more fun

hi oldsamo -

I was wondering the same when I read the post - a true casein would be washable so ive been led to beleive. I recently tried making my own with boiled semi skimmed milk and lemon juice > sieved and washed the solids > blended with soda bicarb then a pinch of borax & left to dry on rad in a plastic tub > ground into a powder in a pestle and works nicely the little I have tried.

Its also supposed as a very good breathable sealer/primer for properties that require traditional solutions, no pun intended :slight_smile:

The addition of glycerine (plus other unknowns) adds to flexibility and flow otherwise it dries to be brittle and only suitable for solid surfaces.

I would imagine that’s why true casein paints wont exist in a commercial environment since the original properties have been adjusted which answers my own question.

Hi paul I find it easier to buy the power and start from there.

Although a lot of people think casein was used a lot, it had a short life in the painting trade. In the A E hurst book and the Practical painter both around 1945 -1950 depending on what edition the product is mentioned. But both seem to favour oil bound distemper.

In earlier publications ie Practical Painter by Paul Hasluck 1909 and house painting by E A Davidson 1911 neither get a mention. Both were trade bibles at the time. And I find it strange neither are mentioned. It is not mentioned in the crace papers or the journal of decorative arts. Again both bibles. There are references to it in early art books and small distemper projects.

We tried it graining on several doors in the Royal Palace of Stirling on plaster. These were faux doors with success purely because of the lime content in the plaster and it worked well.

Personally I think F and B and Rose of Jerico are jumping on the band wagon of traditional paints.

The most used, apart from distemper paint around the turn of the century, was a product called Duresco. This was a silicate paint similar to Keim and died out in the 1950s. In 1893 enough was made to cover 4 million m2 and in trade journals of the period they wrote poems about the stuff. It was produced by the silicate paint company.

Hi oldsalmo, interesting information! - thanks for the pointer - keim - interesting reading.