This is one of Swedens most famous castles -Läckö. It’s a very well kept 17th century castle, though the oldest parts dates back from early Middle Age. A bishop once built a small castle here in year 1298.

And as you can see it’s covered in scaffolds. The facades are to be renovated and that’s why me and my classmates were there last week.

From the beginning the wall surface was made out of lime plaster, but in the sixties that method was considered as old fashion and that the walls was in such a bad condition that a total renovation had to be done. And so they removed all the lime plaster and covered the walls with, modern at that time, Portland Cement/ Roman Cement.

Forty years later it turned out that the Portland Cement (KC Bruk) had caused a lot of damage  such as mold issues and humidity inside the castle as cement behave differently than lime plaster.

Det visade sig att det man på sextiotalet kallade för ”underhållsfritt” höll ett halvt decennium.

A type of red algae, which happen to like cement, on one of the most shady walls. The white spots of plaster consist of a larger amount of iron which the algae doesn’t like

The owner of the castle today -The National Property Board -decided that they wanted to try lime plaster on the walls in the same way they did in the 17th century.

The thing is -we don’t know how it’s made any longer. They don’t know how lime plaster back in the days where made.

So this is Ewa, our teacher. She has been researching about lime and the making quick and slaked lime, and lime plaster for about ten years.

Together with her we got this unique guided tour on the staging while she explained the work with to find out how to make lime plaster.

They began with square sized tests with different lime plaster on the back wall nine years ago.

På 1600 talet använde man sig av blandningen fem delar kalk, en del sand för att göra kalkbruk (5:1). Det är det som är det knepiga. Idag kommer man som mest upp till en del kalk –tre delar sand (1:3)!

Ewa och hennes forskningsgrupp har lyckats göra en blandning på tre delar kalk en del sand. Kalken tas -som den gjordes på 1600-talet- från Kinnekulle. Än vet man inte riktigt hur bra putsen är.

They also began to remove the Portland Cement from the walls. It turned out they did quite a good job putting it on in the sixties. They had to broad axe or saw through the cement. One square meter took two hours to remove.