What's this, chaps?

[Cozzer]

Inside cellar wall....it's like the crystal maze.
If it glints any more under torchlight, I might open it up as Santa's grotto in a few weeks...
The walls have been "painted" - with what? - over red brick at some time (previous resident, more than 25 years ago), but this white fluffy stuff is taking hold wherever brick is visible.
It's not wet down there...nothing metal is rusting...but it does tend to get a bit sweaty/humid if you're down there for very long.

Anything good I can slap on the wall to stop it?

 

[Agent_zed]

Salts coming out of the bricks https://etbricks.co.uk/brick-articles/efflorescence-on-bricks-the-causes-prevention-and-cure/

 

[duke]

Efflorescence as Agent_zed posted.

 

[Richard_C]

Chaps? Is it not possible that a non-chap might know what it is? Cultural fast rewind to 19th century perhaps.

 

[Terry - Somerset]

Don't know what salt coming out of brickwork looks like - but in a cellar it suggests the walls may be 100+ years old and any salt should have dispersed decades ago.

I would be more concerned that it is a fungal growth due to moist, relatively warm conditions and limited air flow. Could be health issue. Or I could be wrong but is it worth taking the risk.

 

[duke]

It is the salt in the moisture which travels through the brick wall.
Exterior to interior.