Primer before plaster? C Mortar plaster

[Ernfrid]

Hello!

I'm going to apply rendering mix C on the walls.
What should I prime with before rendering? Is it okay to use cement mix from Byggmax or do I need something more exclusive?
https://www.byggmax.se/standardcement-p0101

Someone mentioned A mix but I'm not sure what that is.

Biltema has a primer in a can, but wouldn't cement be better?

https://www.biltema.se/bygg/farg/utomhusfarg/mur--och-putsgrund-2000021455

 

[sinuslinus]

What kind of material is it?

 

[Ernfrid]

What is the surface material?

It is concrete hollow block

 

[sinuslinus]

Base coat mortar A or cement mortar A that you apply. Then b or c mortar.

That Buildmax link is for pure cement. It needs to be mixed with sand to be used as plaster. Easier to buy ready-made bags of plaster mortar.

Sounds like you might not be that familiar?
There's some info in PDF form but it's a craft...

https://www.finja.se/storage/ma/3e1...5EB51EC0DCB5EFE8/Hjälp vid putsning_AA_sv.pdf

https://www.se.weber/files/se/2018-04/putsa.pdf

 

[Ernfrid]

Foundation mortar A or cement mortar A that you apply.
Then b or c mortar.

That Buildingmax link is for pure cement. It must be mixed with sand to be used as plaster. Easier to buy pre-mixed bags of plaster mortar.

Sounds like you're not quite aware?
There's some info in PDF form, but it's a craft...

[link] vid putsning_AA_sv.pdf

[link]

No, I wondered if I could prime with cement.

The c-mortar is pre-mixed in a bag.

So cement mortar from Buildingmax can't be used for priming?

 

[sinuslinus]

No, I was wondering if I could prime with cement.

The C-mix is already pre-mixed in a bag.

So can the cement mortar from Byggmax not be used for priming?

Byggmax doesn't seem to have cement mortar a.
What you are linking to is pure cement.
Here's the cement mortar a that I think you mean.
https://www.se.weber/produkter-betongcementvagglagning/standardbetong/weber-cementbruk

 

[Ernfrid]

Byggmax doesn't seem to have Cementbruk A.
What you're linking to is pure cement.
Here is Cementbruk A which I believe you mean.
[link]

Well, then I have to take a detour and buy Cementbruk A. How many bags do you think are needed to coat 30 sqm of wall?

 

[Stickan56]

https://www.se.weber/filmarkiv/filmarkiv-fasadputs-och-murbruk/grunda-ditt-murverk-innan-putsning

Stickan

 

[Ernfrid]

[link]

Stickan

Yes, they recommend redgrund, even more expensive than A bruk. I wonder what the actual difference is.

 

[sinuslinus]

Guessing 8 sacks

 

[Stickan56]

Yes, they recommend rödgrund, even more expensive than A bruk. I wonder what the difference really is.

If you don't want to buy rödgrund, you might as well prime with plaster mortar C.

Stickan

 

[Ernfrid]

If you don't want to buy red base, you might as well prime with plaster mix C.

Stickan

Well, I mean, I'll buy it if I have to, I just thought that mix A is cheaper and several people seem to use it. I don't really understand the advantage or disadvantage of priming with C, A, or red base.

 

[Stickan56]

I mean, I'll buy it if I have to but I thought A-grade is cheaper and several seem to use it. I don't really understand the advantage or disadvantage of priming with C, A, or rödgrund

You're mixing up the terms. Rödgrund is an A-grade mortar and refers to class A.
Cement mortar A contains cement + sand
Plaster mortar C contains lime + cement + sand
Rödgrund contains lime + cement + sand + color

Stickan

 

[Ernfrid]

You are mixing up the terms. Rödgrund is an A-mortar and refers to class A.
Cement mortar A contains cement + sand
Render mortar C contains lime + cement + sand
Rödgrund contains lime + cement + sand + color

Stickan

Ah good explanation, thanks!

 

[Elbk]

If you don't want to buy red primer, you might as well prime with rendering mortar C.

Stickan

so you mean skipping the priming and using mortar c like weber 135 for example? and continue plastering 2-3 cm with only Mortar C?
isn't there a risk that a striped wall will be emphasized later and you can see the joints between the concrete stones?