Plaster A, B or C

[Michel.t]

Really cool, thanks a thousand! I'll get back with the results later, probably in a couple of weeks at least. Really appreciate it!

Thanks for your posts, I'm going to tackle my staircase here this week and it looks just as crappy as yours did 😃
Did you do any polishing, how did it turn out, any lessons learned?

 

[slothy]

Thanks for your posts, I'm going to tackle my staircase this week and it looks just as messed up as yours did 😃
Did you do any plastering, how did it turn out, any lessons learned?

Yeah, plenty! Shoot, I've totally forgotten to follow up and thank those who responded and helped. I'll get back later with exact products, but here's what I did.

First, I chipped off all the plaster quite thoroughly. I probably overdid it and left almost no plaster on the wall, but that made it easier. I brushed it off thoroughly with a steel brush. A hole the size of a fist I repaired with Biltema repair mortar (a 1 kg bag, it hardens very quickly so be prepared to get going).

Then I bought from Bauhaus, a mortar that was some sort of combo so I could use it for both the first coat (like filmjölk, maybe even looser), and then for the bulk.

I then mixed it thicker and threw it on with backhand against the wall as I saw on YouTube. It went pretty well overall, but I think it was too hard (too little water) and too thick a layer (well over a cm, maybe two or even more). A section peeled off the wall like skin on an overcooked sausage. I cut it away and more and continued with the rest. Here I wonder if a simple mesh would have helped enough to avoid making the next batch. After letting it dry for a while, I tried using a float but found it peeled off more than I was comfortable with, so I tested using a wet broom. It turned out okay.

After it had hardened for a few days, I mixed the same mortar but looser and tried throwing it again. It went well but I might have made it a bit too loose. Filled in where it peeled off and smoothed it out a bit. Waited longer before using the float, but then I waited too long so it was rock hard.

Since it was pretty rough and ugly by now, I bought plaster mortar C in the correct fine size (of the gravel grains, that is). This went better.

Then it needs to harden for a couple of months before painting, so I haven't painted until recently. Tried to get Byggmax to measure the color from a sample of the plaster but they didn't have a machine for that. Biltema has dark gray base paint but with a bit of yellow, so it's too warm. Bought a black and a white and mixed them in a separate container until it was roughly right. Since it was an isolated wall, it didn't have to be exact. Used Biltema's primer but not sure if it was really needed.

Painted first with a wide brush. Two coats were needed for coverage, but it came out blotchy. Then I took a roller and went over everything, and it turned out well after that.

A lesson beyond what's above is that it's incredibly dirty work. Both mixing (used a mixer attachment with a drill and mixed in a 90L container from Biltema) and working with it. Now I have some ugly lime-like stains on the floor and steps that are hard to remove. But that's for another day. Will return with pictures.