Paint Technical

May 10th, 2009 | | Paint Technical | 17 Comments

The Problem with "Distemper"

Sherwood's Distemper

Having been involved with Historical and Traditional colours for many years, we are frequently asked for advice on traditional paint.

Every day my team and I at Papers and Paints see confusion amongst members of the general public who come in clutching articles torn from the lighter weight “House Wonderful” type magazines, which urge them to create a “period feel” using “traditional” paints compounded of such things as whiting, buttermilk and a bit of PVA to make it stick. Furthermore every kind of surface can, it seems, be given this sort of treatment in order to create the “distressed palazzo”, “Mediterranean”, “Colonial”, or “Country House” look – all of which seem to be associated with the term “traditional.”

There is confusion, too, over the incidental cross-over between several of the traditional coatings and those that may be regarded as ecologically friendly. Certainly, a white lime wash and a soft distemper may be so regarded, but these qualities are often automatically extended to include all of the less modern paints, no matter what type or colour.

Unfortunately, because of the large amount of money tied up in this area of the decorating industry it is very difficult to find clear dispassionate advice shorn of profit-mongering. The merchants of snake-oil (or should that be peanut oil?) are still very much with us.

Perhaps it is the word distemper that causes the most confusion. Few are aware that this is a generic term encompassing several different coatings. There really is only one type that is of relevance to historical buildings – or any building for that matter.

Soft Distemper, as it is more commonly called, is excellent for the coating of elaborate decorative plasterwork or ceilings. Washed, finely-ground chalk, known as whiting, forms the main constituent. This is loosely bound with a water-soluble glue size usually made from animal bones, horns or skin, often nowadays going under the name of rabbit skin glue.

This is a coating that is made up by the decorator shortly before carrying out the work. In view of the animal glue content once it has been made it has a very limited shelf-life, going rancid after a short time even if refrigerated. By definition, therefore, one cannot buy a true soft distemper in a tin.

Soft distemper is applied by brush and can be removed with a wet sponge when dirty or in need of recoating. Its great advantage is that when applied to ornate plaster ceilings, for example, the detail is not lost as it must be removed before redecoration. An emulsion paint, on the other hand, would add yet another disfiguring layer that will eventually require removal.

As well as its permeability to moisture vapour, which makes it an option in areas inclined to mild damp, soft distemper has the added bonus of being cheap. It is easily made and applied, and can be laid on quickly, provided that an experienced decorator is at hand.

It is not durable however and is neither washable nor suitable for areas of heavy traffic, hence the modern name of soft distemper. As a result, in the nineteenth century, various binders were added to increase its resilience. The additives varied in type and efficiency, and would often have had a profound effect on the technical properties of the paint. One wonders how “breathable” Morley’s Rubber Distemper would have been?




One of the most common sorts of ‘improved’ distempers were the primitive emulsions known as Oil-Bound Distemper, Casein-Bound Distemper or more properly Water Paint. Note here the use of the word ‘emulsion’ to indicate a mixture of two liquids that normally cannot be combined – such as oil and water. It may come as a shock to learn of the very fine line between a bound distemper or water paint and an emulsion paint, as found on the shelves of many builders’ merchants.

Globules of oil suspended in water

By “oil-bound”, it is meant that the paint was an oil-water-emulsion, in much the same way that milk is. Water and oil were combined with a solution of soap or a caustic alkali (such as lime) which saponified the oil, and the mixture was agitated until the oil broke down into tiny globules which remained in suspension as an emulsion.

These early emulsion paints were generally supplied in a stiff paste, which was thinned with water to a brushable consistency for application. On evaporation of the water, the paint dried to a porous film, with the glue – often in the form of casein – acting as a temporary binder during the drying of the oil, which finally hardened the film so that it became moderately wipeable. One of these early brands, Alabastine, was also used as a plaster filler – a questionable advantage as far as a paint goes.



The current trend for labelling or referring to these primitive emulsion paints as distemper is storing a problem for the future. Lulled into thinking that the substrate can breathe under an historically appropriate and pleasingly matt coating it is frequently specified or employed by well-meaning house-owners. Unfortunately, these early form of emulsions had a number of weaknesses. Certainly they had a matt finish and some did have a degree of permeability to moisture, however they did not have the key advantage of soft distemper, and that is its reversibility.

Some years ago, when the Journal of The Traditional Paint Forum, commissioned the Paint Research Association to make comparisons between a typical trade emulsion paint and a Water Paint that was being sold as a distemper, it was found that there was scarcely any difference in the moisture vapour permeability of both systems.

Walpamur

These Water Paints reached their heyday in the mid twentieth century and are best remembered under such brand names as Walpamur and Duresco. Unfortunately, these early form of emulsions had a number of weaknesses.

As the ‘improved’ distempers cannot readily be removed, further coatings tend to be applied on top, and then within two or three schemes of redecoration the problems can start to occur.

The strength of the bond of water paint is less than that of oil paint and, although the coating has some resistance to water, it is absorbent nonetheless. The liquid in a new coat of paint applied on top will soften it to some extent and cause it to swell. Water paint, moreover, is applied in thicker and heavier coats than oil paint. In drying, the paint contracts strongly and, in doing so, exerts a considerable pull on the underlying film, weakening the grip of any parts which are not firmly attached to the surface.

Bound-Distemper causing Problems

A substantial strain is placed on the bond of the old coating, and this cross section vividly shows the problem – the dark line towards the top and marked with an ‘X’ is a layer of a “bound distemper”. Two, three, or even more coats can be safely applied on occasion, but there comes a time when the weight and stress are too great and cracking and flaking take place at the weakest points in the system. Local repair and making good is of no help and wholesale removal back to a sound base is the only way to tackle the problem.

Unfortunately it is not possible to lay down any rule or even give any indication of when failure is likely to take place and the appearance of the old finish is not necessarily a reliable guide to its stability. Much will depend on the quality of the old coating and the number of coats on the surface. The atmospheric conditions to which the finish has been exposed may influence its behaviour; in a room subject to a certain amount of condensation, for instance, the repeated wetting and drying of the surface will progressively weaken the binder of the water paint.

Is it worth taking the risk merely for the appeal of using a product with an esoteric or rose-tinted name on the label? Surely the decoration and protection of the building is worth more than allowing oneself to be manipulated by the marketing man?

This is the sort of information that customers of Papers and Paints can expect to be given if they seek our advice. During our fifty years of trading we have built up a considerable knowledge on this and other decorating issues. We may not be able to offer you a “lifestyle” but we can certainly help you decorate your house.

Patrick Baty


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Comments (17)

Reply
Steve KnightNo Gravatar » 21. May, 2012

Having problems painting Polycell Textured Paint to a ceiling. After reading your comments now think there is a layer of distemper on it. House was built in the 50′s. Do you now the best way to get rid of it. Have heard that using a oil based undercoat to seal it will allow me to over paint with the textured paint. What are your views as I am running out of patience having sanded the ceiling 3 times now and nothing sticks.

Reply
PatrickNo Gravatar » 22. May, 2012

Your first port of call should be Polycell, who will have a technical advice line. It is possible that you have a ‘distemper’ on the ceiling. If a ‘soft’ variety this can be removed by sponging. If a ‘bound’ variety, sponging will have little effect. You might find that one of the products made by Zinsser will do a better job than an oil-based undercoat.

Reply
Rik TyeNo Gravatar » 25. Jun, 2013

Hi I am on a job at the moment (grade B listed church) where in the past the walls have been emulsion, now the architect wants distemper/lime wash put back on.
Now I know u should was distemper off b4 painting but how about the opposite ??? Can u lime wash over emulsion?????

Reply
PatrickNo Gravatar » 26. Jun, 2013

Thanks for getting in touch. No, I’m afraid that one cannot apply a conventional limewash over emulsion paint.

Reply
Lindsay McDonnellNo Gravatar » 26. Jun, 2013

Hi Patrick,
I would really appreciate your advise.
We are renovating a grade 2 listed stone farm house and have replastered internally with lime plaster. What should we be using to paint the walls with? I was considering a lime wash, but there is considerable discolouration in some areas which I’m not sure will be covered by a lime wash. We also have the added issue that Gypsum has been used (by a previous owner) on some walls- which obviously Lime wash is not suitable for and I am concerned about continuity of colour.
What would be the best paint to use on the Lime plastered walls and is there anything I can get that would be suitable for both those and the Gypsum walls? This is a family home, so obviously we would ultimately require a something that is both breathable and durable- and the two (as far as I can see) seem to be mutually exclusive.
Thanks in anticipation
Lindsay

Reply
PatrickNo Gravatar » 26. Jun, 2013

Thanks Lindsay. You are absolutely right – breathable and durable are almost contradictory. I think that I would use either a cheap Trade emulsion, such as Dulux Supermatt or Classidur Golden Classic. Some years ago when editor of the Traditional Paint Forum journal I commissioned a comparative study of Trade emulsion vs a bound distemper (more properly called ‘Water Paint’) and the emulsion was found to be superior, cheaper and not prone to the terrible problems that the ‘distemper’ will give you.

Reply
Matthew WilliamsNo Gravatar » 14. Aug, 2013

Excellent article on ‘distemper paint’- I’m helping redecorate/restore a Victorian house, and finding paint crumble away onto the roller. This article explains why- though the solution will take days of scraping a 3m high ceiling with decorative cornice..! The room has had some damp through a damaged bay too, which presumably has acceclerated the old paint decay. We inend to use modern emulsions to decorate- budget is modest, though would like to restore the plasterwork at some point. Also, theres a stone fireplace but Im worried about exposing lead, theres kids in the house, Ive tried the chemical peels but they still leave crumbling dust and residue.

Reply
PatrickNo Gravatar » 14. Aug, 2013

Thank you Matthew. Yes. I understand the situation. I am afraid that you are faced with the problem that many other houses threw up twenty years or so ago – how to deal with old distemper. There really is only one way, and that is with damp sponges and lots of elbow grease. You need to take off as much as you can. You might then use a primer sealer of some kind and apply the emulsion to that. There is unlikely to be lead paint on the ceiling, but you will have it elsewhere. There shouldn’t be a problem, provided that you wet-abrade, clean up the residue immediately and Hoover regularly to eliminate dust. You must then ensure that the bags of dust are disposed of following your Council’s guidelines. Good luck.

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Jenny MeehanNo Gravatar » 17. Jan, 2014

This is a brilliant read! I love the historical images too! I am an easel painter/fine artist, and have spent a lot of time researching both silicate mineral paints (modern and old), casein painting (in a fine art context as well as buildings) and recently distemper, as part of my teaching…artist’s watercolours, gouaches, and poster paints, of course, all being forms of distemper, (though without the rabbit skin glue of traditional decoration/fine art painting!) Thanks for putting this together! May I include a link to this on my blog? It’s one of the best things I have found on distemper? Jenny Meehan

Reply
PatrickNo Gravatar » 17. Jan, 2014

How kind of you Jenny. It’s proved to be a very controversial subject. I’m afraid that some people do not like having their rose-tinted spectacles removed. Yes, please do link to it. Thank you.

Reply
sarah russellNo Gravatar » 27. Jan, 2014

Hi I’m having a few problems with distemper at the mo in in an old council house I’ve already had it confirmed the it is in my kitchen because it is green can you possibly clear up an argument I am currently having about 2 other rooms. Does distemper always have to be green as in the 2 other rooms the paint is flaking away and underneath it it is more of a beige colour and when touched leaves a chalky layer on your hand and they are trying to say it doesn’t have the same characteristics (all because it’s not green) I would very much appreciate it if you could help clear this matter up please. Thank you

Reply
PatrickNo Gravatar » 27. Jan, 2014

Thanks for writing in, Sarah. The colour is no indication of whether it is a distemper (soft or otherwise). If the surface is chalky the chances are that it is distemper. Subsequent paint will not ‘stick’ unless you remove this.

Reply
sarah russellNo Gravatar » 27. Jan, 2014

thank you for clearing that up for me it is chalky and paint just flakes off of it thank you once again ill be able to get it sorted alot easier now thank you

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Aida ButlerNo Gravatar » 14. Apr, 2014

The house next door has an extention which forms part of my Patio.It is a brick wall and I would like to paint it White I am in a Basement,which does not get much light.Thank you for your help Aida

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PatrickNo Gravatar » 14. Apr, 2014

You certainly could paint it with a masonry paint, but bear in mind that once painted brick can seldom be stripped. You would also have to maintain it.

Reply
margaret saliskeNo Gravatar » 29. Jun, 2014

I am attempting to clean a stenciled 19th century ceiling that I have taken samples of and had examined under microscope. It seems to be a distemper. No oil only protein in the layers. The surface is very matte and fragile. It stains with solvents. I am attempting to use dry cleaning methods. Have you had any success with cleaning accumulated dirt off these surfaces. There is very little damage overall from water/ cracking/flaking so would like to avoid removing and repainting such a complex decoration that unfortunately is very dark with soot.

Would appreciate any input.

Reply
PatrickNo Gravatar » 02. Jul, 2014

Margaret, thank you for your interesting question. The best and only source of information that comes to mind was written by Morgan Phillips twenty years ago in a chapter entitled: ‘A Victorian Trompe l’Oeil: The Restoration of Distemper Paints’ this was published in Moss, Roger W.(ed.). Paint in America. The Colors of Historic Buildings. The Preservation Press. Washington, D.C., USA. 1994. I hope that this is of use to you.