Rendering finish from Finja/Weber/Combimix?

[KjellTimell]

I will plaster the walls in the basement level with C mortar, fine-grained, and have been looking at both Finja and Weber as suppliers of mortar.

Weber:
https://www.weber.se/fasad-puts-och...tem/putsbruk/weberbase-136-finputsbruk-c.html

Binder: Lime and cement
Aggregate: Crushed dolomite and sand 0-1 mm
Composition: KC 50/50/650 (What does 650 stand for???)

Advantages:
- More water required for a 25Kg bag, 5-6L, which should give a thinner mortar that is more like spreading joint compound on a wall than plastering it.

Disadvantages:
- Price, 160kr/bag at XL-bygg, 110kr at Beijer

Finja:
https://www.finja.se/produkter/gjuta-mura-putsa-laga/kc-putsbruk-c-fin

Binder: Lime and cement
Aggregate: Natural sand 0–1 mm
Composition: KC 50/50

Advantages:
- Price, 65kr/bag from Fredells is clearly more enticing and seems reasonable!

Disadvantages:
- Less water required, 4L, makes me worried I will get a drier mortar that is not as thixotropic and easy to handle. I plan to apply the mortar with a trowel and smooth it.

Combimix:
http://www.combimix.com/se/produkter/fasad/putsbruk/putsbruk-c-fin-cs-ii

Advantages:
- Price, 49kr/bag (20Kg), the comparative price would be 62kr if it were a 25Kg bag, i.e., the same league as Finja
- Slightly better water ratio, 18% which would give 4.5L/25Kg bag, but not as good as Weber.

Disadvantages:
Still worried that there is too little water, that it becomes too dry for fine plastering/spackling!

Question:
What are the risks if one exceeds Finja's recommended water amount and uses 5-6L like Weber to get a thinner mortar?
Will there be reduced strength, risk of cracking during curing/evaporation, or other side effects?

I expect to plaster about 4-5mm/m², which requires over 10Kg of dry mortar per m², and there is a total of 110m² that needs to be prepared, which would require 1100kg or 45 25Kg bags.

 

[ktm250]

Composition for C-use is standard 50/50/650 (lime/cement/sand). Too much water creates a weaker mortar with a risk of cracking during the curing time. Post-moistening is important.

 

[KjellTimell]

Okay, then Finja and Weber are equivalent with the difference being that one states 5-6 liters and the other 4L, and that Weber also contains dolomite and not just sand as aggregate. The question then is whether Weber really has a greater tendency to crack than Finja? Or if one could just as well use 5-6L on Finja too.

 

[Zango]

6 liters of water in Finjas will become runny, nothing I would polish with.
Weber has more of the fine-grained aggregate, and thus can hold more water.
Even though both have 0 - 1 mm.

 

[KjellTimell]

Okay, does anything justify Weber's price or will they be perceived as equivalent once the mixes are combined and ready to use?
I was planning to apply the mix more with a skånska, thin layers, and float the surface.