White powdery deposit on drying plaster

I had a damp problem in my kitchen, cause unknown but contributing factors may have been:
1. House empty for 2 years. 2. No heating, ventilation for 2 years 3. Kitchen is above a cellar which had become very damp with condensation 4. Kitchen floor is stone flags, which seems to have soaked up moisture from the damp cellar 5. The plaster on the kitchen walls went right own to the floor, the stone flags and was therefore able to soak up moisture. 6. The was also a dodgy water stop tap under the sink.
The steps I have taken to address this are:
1. Opened up the cellar windows (after fixing metal gauze to prevent vermin entry) to get some ventilation. 2. Hacked off two inches of plaster in the kitchen at the foot of the walls to break the plaster's contact with the stone flags. 3. Switched on the heating and opened some more windows 4. Got a dehumidifier in.
In 5 weeks this has made a big difference, with the kitchen walls now almost completely dry.
On one part of the wall, I hacked off some loose top layer plaster to leave the browning undercoat. The undercoat was also damp, but dry now. I have however noticed on this now dry browning a white powdery deposit, and I'm not sure how to read this. Is it a sign of fungal rotting, or is it something harmless that can just be swept away?
Kind regards,
Saeed
sr_ng 786
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It's due to moisture moving through the wall and evaporating at the surface, leaving behind the salts it was carrying. Brush it off and if it reforms, you still have moisture coming through the wall.
--
Andrew Gabriel

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