Basement renovation ventilation problem

[Skogen29]

Hello!

Last summer, I re-drained and insulated the foundation with isodrän to properly finish the basement now. There wasn't much moisture in the basement before the re-draining, but the plaster had loosened on the interior walls low down towards the slab in one room. Now I have removed what had crumbled and scraped off all the old paint/wallpaper. I applied new plaster low down and put on the first layer of broad putty.

Question.
On the plaster before I applied the broad putty, there was some white stuff that could be removed just with fingers, and after applying the putty, something similar appears and the putty crumbles and detaches from the wall. What is the issue and what should I do to fix this? I have had a dehumidifier in the basement since I drained it to dry the walls faster.
The humidity level is between 35-55%.

Thanks in advance!

 

[Utsliten och utdömd]

Probably lime efflorescence, do you have any pictures?

How long did you wait after plastering the walls? Lime efflorescence indicates moisture and can come from the moisture in newly applied plaster. It's important that it has dried properly before painting or similar on the plaster.

 

[Skogen29]

Probably efflorescence, do you have a picture?

how long did you wait after you plastered the walls? Efflorescence indicates moisture and may come from the moisture in freshly applied plaster. It's important that it has dried properly before painting or applying anything on the plaster.

Thank you for your response. Hmm about 2 days I think I waited, maybe should have waited longer... but I removed it and applied a new layer of filler. I'll upload a picture if it comes back.