In message , Andrew Gabriel
writes
In article ,
(Niel A. Farrow) writes:
sheds.

If I use unwashed sand will I have problems?

I think the only difference it makes to (building) sand is to
wash away the very fine particles, which otherwise act as a very
powerful yellow pigment. However, this is just by observation;
I've never actually seen a description of what washing sand is
meant to do.

I always thought it referred to washing sand that may have come from a
marine source to get rid of the salt. Which AIUI can affect the setting
of the mortar
--
Chris French, Leeds