Rendering mortar B on war concrete

[dallas84]

Tried applying plaster B on war concrete just now. It adhered awfully poorly, and was a total pain! It was the first time ever that we tried plastering, and the idea is to plaster the interior walls of the basement.

How do you go about getting the plaster to adhere better to the wall? I should perhaps add that we washed the wall before, and dampened the wall.
Is there any point in slathering the walls first?

 

[Jansson69]

Yes, since you have war concrete, you need to add asbestos fibers to the mix for it to bond well 😉😆

Do you have pictures of how it looks? Is the wall clean of paint and other stuff?

 

[dallas84]

Yes, because you have war-time concrete, you must include asbestos fibers in the mortar so that it meshes well😉😆

Do you have pictures of how it looks? Is the wall clean of paint and other stuff?

I can get pictures tomorrow! Haha, I really hope I can avoid asbestos fibers 💀😅

 

[Thomas_Blekinge]

Tried applying plaster B on war concrete just now. It adhered terribly poorly and was a total pain! It was the first time ever that we tried plastering, and the idea is to plaster the interior walls in the basement.

How do you get the plaster to adhere better to the wall? I should perhaps add that we washed the wall beforehand and dampened the wall.
Is there any point in so-called slamming the walls beforehand?

I've also tried plastering basement walls (80s) and find it generally terribly difficult to get it to stick. I've seen many videos on it where it looks super easy, but reality is different.
Unfortunately, I have come to the conclusion that I can't do it, even though I usually do most things at home myself, including electrical work and plumbing.

 

[cpalm]

How do you go about making the plaster adhere better to the wall?

How do you "apply" the plaster?
If the surface is smooth, you probably need to apply a primer first.
Otherwise, the consistency of the plaster is also crucial for adhesion; it should be smooth and "creamy."

 

[dallas84]

How do you "apply" the plaster?
If the surface is smooth, you probably need to apply a primer mortar first.
Otherwise, the consistency of the mortar is crucial for adhesion, it should be smooth and "creamy."

Tried doing it like in all the videos, i.e., throwing the mortar on! Spackling it on was completely impossible! I think the consistency was close to what's desirable, but it's hard to know!

What does a primer mortar mean? What could it be?

 

[Claes Sörmland]

What is a "grundningsbruk"? What could it be?

It is a mixture prepared like porridge with a high cement content. It can be applied with, for example, a mason's brush, creating a textured surface that the plaster adheres to well. You can buy products called "grundningsbruk," but in the past, people mixed it themselves, essentially an A-grade mixture in porridge form.

You can also reduce the risk of cracks and achieve better adhesion to the substrate by using a mesh. You nail up a fiberglass mesh. Then apply the "grundningsbruk." Then you're ready to plaster.

Otherwise, the solution around the time of war concrete was to plaster with lime mortar. It's creamier and stickier than cement-based mixtures.