The Natural Philosopher wrote:
wrote:

The Natural Philosopher wrote:

Its a sign thet the bricks are wet and porous: Salts leach out of the



cement and migrate by osmosis to the surface of the brickwork



These (the ones on ebay) are allegedly engineering bricks and haven't
been layed but in any case I doubt the latter part is true. AIUI the
salt is in the bricks themselves.

I am not so sure.

Bricks are stored ourtside for many months, but I have never seen them
leach salts until they are laid with cement.

I laid some that had been outside in teh rain for 50 years. They still
leached after laying.

I thought bricks had to be dry before laying or the mortar wouldn't
stick to them properly. AIUI the dryness of the brick draws in some of
the fluid from the mortar (along with some mortar particles) to
producing the bond. I've not laid bricks though so I might be speaking
from the wrong orifice.