“House doctor” laments smothering effect of plastic paint on wooden walls
Architect Panu Kaila writes new book on exterior painting calls
By Antti Manninen
Architect, Professor Panu Kaila, also known as a “house doctor”, bends over one of his “patients” in the Helsinki district of Vallila, renowned for its distinctive wooden houses. The foundation of one of the buildings is cracking badly, because damp has pushed out from beneath the layer of plastic paint. Before it exploded, the surface the surface of the paint was a hard plastic film that did not breathe.
Suffering from the same problems in the 1970s were the Helsinki Cathedral, the main building of the Finnish government, and many other public buildings.
Plastic, or latex paints have caused much damage to the outer surfaces of wooden buildings as well. Kaila has published a new book with sad examples of latex surfaces just a couple of years old. The paint has been peeling off, because the dampness inside the building could not evaporate from beneath the surface boards. The paint is shed like the hair on a mangy dog.
However, the old oil paint left underneath the latex is still going strong.
The worst of the damage in Helsinki has already been fixed. However, Kaila believes that there are many examples of incorrectly painted wooden houses and plastered surfaces in rural areas, where painted surfaces a couple of years old are already blistering.
A big job awaits, because the latex first needs to be scraped off so that the surface might be repainted with a more durable surface.
However, Kaila does not recommend sand blasting, which can easily spoil the surface cladding. An example of this can be found in Vallila: the City of Helsinki hastily sandblasted the outsides of old wooden houses for the housing fair of 1981. The sand wore furrows and dents into the walls.
The world conquest of plastic paint began in the 1970s, when the paint industry wanted to brush aside the traditional lime, and oil-based paints. “The industry wanted paints that were easy to manufacture, which worked well in automatic processes, and which were cheap”, Kaila says.
That is why large paint manufacturers lusted after public buildings as examples.
“They made people believe that traditional lime-based paint would not hold up to polluted city air. Even experts were cautious, as they did not like to criticise the industry.”
Instead, attention was focussed on irrelevancies, such as points of contact on outer walls. “However, it is obvious that plastic paint was the problem”, Kaila says. He notes that lime paint has been used on plaster everywhere for 2,000 years, and wood has been painted with oil-based paint for 200 years.
Professor Panu Kaila is an expert in traditional methods of painting. a few years ago he wrote a book on traditional external painting. His new book continues on the subject, from the 1950s to the present day.
According to Kaila, the postwar period was a time of frenzied changes and new methods, both in the paint industry and in other types of construction. He gives examples from Sweden and Norway, where plastic paints caused serious damage and led to lawsuits. The walls of wooden houses simply rotted away and crumbled beneath the plastic paint. Acrylic latex paints were the most watertight and the worst.
In Finland, paint factories would generally only agree to replace the paint. The factories did not compensate for damage to plaster, which they said was of poor quality to begin with.
Kaila says that the path taken by industrial paint is a four-step system. The raw materials industry produces only raw materials. The actual paint industry, for its part, wants easy and cheap substances. Then come the retailers and building contractors, who are interested in uniform quality and a long shelf life in the can. Contractors want to be able to wash their hands with minimum effort.
“Last comes the house owner, who wants durable paint, but that is of no interest to the others”, Kaila says.
The raw materials for traditional paints come from nature, and that is why their quality fluctuates.
“Linseed oil is different from one year to another, and ochre varies according to where it was excavated. It is more difficult for the industry, of course.”
In his popular book, Kaila the “house doctor” lists a surprisingly large array of traditional methods of painting. If wood that greys naturally is not good enough, it can be covered up with distemper, milk paint, oil plaint, or lime paint. There are other ways as well.
Kailaa, who worked at the National Board of Antiquities for 20 years, has mixed and tried various types of paints, collected recipes, and developed paints of his own. He also warns about confusing names that are sometimes used to obscure the real content and characteristics of paints.
Helsingin Sanomat / First published in print 26.10.2008
ANTTI MANNINEN / Helsingin Sanomat
antti.manninen@hs.fi
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| 28.10.2008 - THIS WEEK |
 “House doctor” laments smothering effect of plastic paint on wooden walls |
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