.. wrote:
Derek Geldard wrote:
Quiz, what 's caused the staining on this gable end?

http://www.leodis.net/display.aspx?I...1&DISPLAY=FULL

ISTM that finial (?) is well above the height that roof water could
spill over, that seems to be happening further down the roof in a
symmetrical fashion. and to a much lesser extent anyway.

There won't be any leaking gutters, how's all that water get up there,
assuming it is water?

DG

soot & pollution washed down by rain ?

The stonework looks like the industrial grime of old Leeds has already
been cleaned off, except for this dark staining which won't come out. It
could perhaps have been caused by metal salts, dissolved by acid rain
from a weathervane or some other metal ornament (conveniently, just
above the top of the picture). The main staining on the gable looks
consistent with rainwater running down the curved finial in two streams,
and then down the wall and over the arch.


--
Ian White