How should I fix my failed plastering?

[PeterWelzien]

Hello. We recently bought a house from -38. In the basement, there's a room that was previously a garage. The previous owner bricked up the basement door and put up a frame and insulated the room from the inside. We tore out all the interior because it was quite rotten. Three of the walls are plastered and look completely fine, but the opening where the door used to be was completely without plaster.

I have never plastered before, but I gave it a try. I used plaster mortar M, but since I didn't wet the wall beforehand, the plaster set almost immediately when I applied it. The result, in short, was not very good. I made another attempt with plaster mortar C, and this time I wetted the wall before applying the plaster. It was better, but not perfect. In hindsight, I've realized that I should have used a long board to smooth out the plaster.

Here's how the wall looks now:


How should I proceed to fix the wall? It doesn't need to be as smooth as a baby's bottom. It's enough if it looks like the other walls:


We only plan to paint the walls with a suitable diffusion paint.

 

[parper]

Can't you try sanding with a giraffe sander (a sanding disc on a handle with a vacuum cleaner outlet)?
You should have used a float..for example this one http://www.biltema.se/sv/Bygg/Kakel-och-mura/Murarverktyg/Putsbrada-86660/

Worked with circular movements after you had applied the render, both directly and a bit later when it had set a little bit...

 

[SBH]

see that as priming.
situation anew. water first and more plaster later.

you should have moistened first. slurry. then apply plaster.

 

[PeterWelzien]

You should have used a float board... like this one [link]

Worked with circular motions after you applied the plaster, both directly and a bit later when it had set a little...

Will it be better if I use a longer board? I've seen that Bauhaus has really long (1 m) boards.

 

[parper]

Well, I'm not a pro either, but from the experience I have (I got help from a mason), he uses a small trowel. It's probably up to each person, but when I've done it, I think the small trowel is more manageable.

The surface will become very smooth and even when you've gone over it with the trowel. The advantage of the long one is probably that you get a larger area even all at once and you may get an overall more even wall. But you need to have experience for it to look very nice. However, my opinion on basement walls is that they can have some waves to make them look a bit more lively.
However, the plaster should be smooth and nice.

I've barely heard of Putsbruk M, A, B, C are a bit more common. I have used C plaster, as it's a lime-cement-based plaster that's reasonably good and cheap.
You can also use gypsum (maybe called M plaster?), which is a bit more expensive but much easier to work with.

In any case, when I have worked with C plaster it tends to be quite loose and it doesn't dry immediately as you described it.
/P