On 10/04/2012 11:54, AL_n wrote:
stuart wrote in news:Qblgr.68233
:

Rockwool holds moisture but doesn't absorb it (if that makes any sense).
A J cloth works in a similar way, as do microfibre cloths etc.

Certainly rockwool holds water after it has become drenched. However, if
you were to half-submerged a wad of it in a pot of water, would the
unsubmerged part soon become wet too, say by capillary action, (in the way
some high-absorbent synthetic mops do)?

Al

Dunno. It's full of air (like supermarket bread), so I suppose it might
float initially.
ISTR there is no capillary action with a JCloth i.e. only the bit in the
water gets wet. In fact, I've never been able to demonstrate wicking to
my own satisfaction.