Resembles mold on newly plastered wall in basement

[cammen]

We are renovating the basement, have lowered the floor level, insulated, and laid a new slab with underfloor heating, not yet turned on as window installation is still ongoing. The basement is on a slope, with the wall that is below ground (about 180 cm of 230 cm is below) plastered about 3 weeks ago.

Now something that looks like mold has appeared all over the newly plastered wall. I tried to put a mold spot in water but it doesn't dissolve, so it doesn't seem to be efflorescence.

The basement has not yet been drained and there is external water pressure. Previous measurements by craftsmen showed that the wall was dry enough that draining was not necessary. I will now drain and install a dehumidifier. See pictures of what looks like mold spots.

1. What should be done with the mold itself in the short term? Should I remove it and if so, how?
2. What could be the underlying cause of the spots? They have only appeared on the newly plastered surface, not on other parts of the old wall that are below ground.

Grateful for answers.

 

[sinuslinus]

What kind of plaster is it? Looks like gipsputs.

 

[cammen]

Hello,

Yes, the craftsman says it is plaster:

https://www.bauhaus.info/gipsputze/rotband-haftputzgips-30kg/p/13874415

 

[anders07]

If it is Bauhaus plaster, it contains cellulose, and that's probably what is molding! There is pure plaster, but it is directly unsuitable to use plaster on exterior walls without insulation/drainage. It should be plaster that is diffusion-open, and it must be painted with diffusion-open paint (plaster/silicate paint).

 

[sinuslinus]

If it's gypsum plaster on the outer wall, I would complain about the entire job.

 

[danne_88]

As everyone else has already said, plaster on exterior walls is not so good!

 

[cammen]

Thanks for the response, reklamerat, it's being redone.