John

Nice explanation.  Good thing it can be found by search engines at the web archives of BP!  Maybe Michael Edison should post it on his web page as a technical note for all those purchasers of his mortar compounds.  Certainly outlines clearly what I was trying to explain to a subcontractor several years ago about why he needed to pre wet and keep damp the sandstone joints he was repointing in lime mortar!  Needless to say, he didn't, and the joints simply sanded away!  So he came back and tried a second time.  Unfortunately, he slipped in a stronger mix with some cement ... we will see the effect of this in twenty years time ... look out for my posting!

Cheers

david west