Certainly agree with Mike here...mix design is key.  But let's not forget
about the talented masons who have not chimed in here.  In addition to good
proportioning, water repellency is certainly aided by a good joint profile,
appropriate time of tooling, and of course not squeezing the mortar in with
a pastry bag.  I've seen a number of well placed Type O mortars or "weaker"
that resist and deflect water infiltration better than poorly placed Type S
mortars.

Out of curiousity Ilene, do you have any handle on the root cause of the
mortar failure or what the original mortar might have been?

John

-----Original Message-----
From: The listserv where the buildings do the talking
[mailto:[log in to unmask]] On Behalf Of
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Sent: Wednesday, April 08, 2009 1:07 PM
To: [log in to unmask]
Subject: Re: [BP] Grace's Dry-Block

Properly proportioned mortar with properly graded sand does not leak. You
don't need water repellent admixtures if you have decent mortar. 
Mike E
------Original Message------
From: Ilene R. Tyler
Sender: The listserv where the buildings do the talking
To: [log in to unmask]
ReplyTo: The listserv where the buildings do the talking
Subject: [BP] Grace's Dry-Block
Sent: Apr 8, 2009 12:34 PM

 New thread: does anyone know this product - Grace's Dry-Block II Mortar
Admixture? Can it be used as a mortar additive to Type N mix for
pointing glazed terra cotta to improve water repellency of the mortar?
I'm concerned about trapping moisture in the assembly, and causing more
damage than already occurs with the failed mortar. 

Thought I'd throw it out there for you all to chomp on...many thanks.


QUINN EVANS | ARCHITECTS 
Ilene R. Tyler, FAIA, FAPT, LEED AP
v 734.663.5888

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