David (and Steve)-

Just some thoughts:

 > Just make sure you do not use any lime when
 > repointing. Make damn sure you
 > use plenty of Portland cement and you will not have
 > to worry about another
 > brick moving ever again.

 Steve

Steve-

This is not meant to be confrontational (much), but my guess is that either
you are not a preservation brickmason, or you have not had much experience
with old masonry.  Shoving a relatively hard material into the joints between
relatively soft (what I am presuming at this point are clay, not shale,
bricks) bricks, will likely only accelerate any ongoing deterioration of the
brick.  Not to mention the fact that repointing with Portland will still
leave a substantial amount of the original lime mortar in-place as the
primary setting or bedding material.  Dissimilar materials typically do not
react well to each other.  Lime mortars have been used for centuries
successfully, just ask the Romans.  I guess that my point here is that your
comment is sort of the equivalent of saying something like, "Well the plaster
on the Sistine Chapel Ceiling is cracking, so I suggest you replace it with
drywall, because that won't crack...oh and use acrylic paint this time, I
heard it lasts longer".

Further,  To David this time:

The "heritage" issue is really the least of your problems.  The first and
foremost issue that needs to be addressed is "why is the mortar failing"?
Mortar does not just, I repeat, does not, dry up to a dust consistancy just
because it gets old.  Something, somewhere on that building is creating a
condition that is damaging the mortar.  My best guess is that moisture is
infiltrating  the wall...I know that without seeing it that this is a rather
bold statement to make from hundreds of miles away...but trust me on this
one.  It is likely that moisture is creating a condition that is allowing
soluble salts to deteriorate the mortar or there is some sort of freeze-thaw
thing going on. Mortar damage can almost ALWAYS be traced to a cause and
effect relationship.  Until you know what that relationship is (i.e. this is
why my mortar is falling out and this is what needs to be done to stop it)
then anything you do is at best temporary and potentially harmful.
ESPECIALLY IF YOU GO PUTTING PORTLAND CEMENT BASED MORTAR INTO A WALL THAT
WAS ORIGINALLY CONSTRUCTED WITH LIME MORTARS.  Incidentally, the ratio of 3
parts sand to 1 part lime is probably a little off.  Due to the deteriorating
condition of the mortar, some of the lime has likely leached out.  This would
effect the data in the digestive evaluations that you may have undertaken.
My guess, again site unseen, would be that a ratio of 2 parts sand to 1 part
lime is probably more accurate.  If you decide to do this job right, and use
lime mortar, and yes there is a "right" and "wrong" way, the mortar will
outlast you and I and the next generation...IF YOU FIX WHAT IS MAKING THE
MORTAR FALL OUT FIRST.  If you would like some help evaluating your problem
and developing repair methodology that is specific and appropriate to your
site, drop me an e-mail.  If however you would like to go back in 2-3 years
and explain to your clients why the faces of their bricks are spalling and
turning to dust..."make damn sure you use plenty of Portland Cement".

Mark D. Clark
Southwest Restoration

 P.S.  There would be no "heritage Nazis" if there weren't so many Fascist
Portland Cement "experts".  And finally (ah finally) in closing...Lime is
"the good stuff".

--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>