I have read a lot about plastering walls, but I still have some questions. No matter where I read, it always says something like "Ask your building supplier." if there are any more difficult questions. Since the building supplier is usually a 19-year-old kid who doesn't know anything, I'm asking here.
1) If you have lime mortar on the walls, you should be careful when choosing plaster. But why?
2) How do you know if it's "lime mortar" on the walls? Is it always that in old brick houses?
3) At Bauhaus, they said that Plaster B was better than Plaster C because the latter contained more cement and therefore "ate up" the old (lime) plaster. The problem was just that Plaster B had large grains and was therefore hopeless to use for an amateur. Was Bauhaus right?
1) If you have lime mortar on the walls, you should be careful when choosing plaster. But why?
2) How do you know if it's "lime mortar" on the walls? Is it always that in old brick houses?
3) At Bauhaus, they said that Plaster B was better than Plaster C because the latter contained more cement and therefore "ate up" the old (lime) plaster. The problem was just that Plaster B had large grains and was therefore hopeless to use for an amateur. Was Bauhaus right?
1) You shouldn't have a stronger layer on the outside of a weaker one. It should be the other way around in cases where you want different strengths in the mortars. Weakest on the outside. Otherwise, there's a risk it will detach from the bricks.
2) The simplest way is to take a piece to someone who understands the difference. In the past, a mixture of lime and cement was often used in the plaster. They wanted to save on the expensive cement. You can test it yourself too - look it up in a textbook to see how it's done.
3) No, it was probably the 19-year-old you talked to. Mortar is available in classes from A to E where A is strongest and E weakest. All mortar classes come with different grain sizes. Common grains are 0-3 and 0-1 mm. You can also mix it yourself if you want a very specific grain size. Mixing yourself is cheaper if you need a lot of mortar.
2) The simplest way is to take a piece to someone who understands the difference. In the past, a mixture of lime and cement was often used in the plaster. They wanted to save on the expensive cement. You can test it yourself too - look it up in a textbook to see how it's done.
3) No, it was probably the 19-year-old you talked to. Mortar is available in classes from A to E where A is strongest and E weakest. All mortar classes come with different grain sizes. Common grains are 0-3 and 0-1 mm. You can also mix it yourself if you want a very specific grain size. Mixing yourself is cheaper if you need a lot of mortar.
Thanks for the answers!
If I live in an old brick house from 1929 and want to apply plaster, can I use Putsbruk C (e.g., Maxit's Putsbruk C hand)? Or do I need a weaker one? According to Maxit's brochure, Putsbruk C seems to be the one to use, but they recommend contacting a building supplier if you're unsure.
If I live in an old brick house from 1929 and want to apply plaster, can I use Putsbruk C (e.g., Maxit's Putsbruk C hand)? Or do I need a weaker one? According to Maxit's brochure, Putsbruk C seems to be the one to use, but they recommend contacting a building supplier if you're unsure.
I have a 40's house and drive a C
The only way to be completely sure you're using the right one is to bring a piece of chipped plaster and ask someone who knows. Then swing by where you see masons working, for example, and see if you can bump into someone who looks experienced.
You might even get lucky with salespeople at the stores as well, some are very knowledgeable and former craftsmen.
You might even get lucky with salespeople at the stores as well, some are very knowledgeable and former craftsmen.