Chris,
You may be seeing the newly tooled mortar with cement and lime on the
surface of the joint. Often, the joints are left this way for the cement and
lime to weather off over time. The joints can be artifically "weathered" by
using a wood "slicker" to provide a rough surface or the mason could return
after a month and clean the building with mild acids which will remove
(etch) the cement/lime from the surface exposing the sand. One should
remember that any artifical "weathering" effectively reduces the life span
of the mortar - so goes the cost of instant gratification. Also, in my
experience, even after a perfect matching of the cement color and sands, a
"toning down" of the color is needed which often leads to small inclusion of
ochre.
Thanks,
Eric Hammarberg
Vice President
Thornton Tomasetti
51 Madison Avenue
New York, NY 10010
T 917.661.7800 F 917.661.7801
D 917.661.8160
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This message sent from Treo, please pardon spelling and other mistakes.
-----Original Message-----
From: Gabriel Orgrease [mailto:[log in to unmask]]
Sent: Tuesday, June 12, 2007 06:13 PM Eastern Standard Time
To: [log in to unmask]
Subject: Re: [BP] mortar coloring
[log in to unmask] wrote:
> But >>what do you add to mortar to make it sandy beige?
> Whatever it was, the "waterproofing company" which worked on 915 West
> End Avenue (1922, Rosario Candela) decided to save it for something else.
c,
Are you suggesting that the current mortar is too white? Or that it is
not subtle whatever the color?
First ingredient... one needs to care what color the mortar was, is and
will be to begin with.
2nd ingredient... one needs to have a clue how to adjust for colors
(this may also presume some ideas as to ingredients & proportions).
3rd ingredient... it helps if one is sensitive to the subtle differences
between one mortar and another.
General rule of thumb is that one try to match the color of the original
aggregate, to let the aggregate provide the primary color as it will be
more enduring with weathering. So in this case a Long Island sand is a
typical sandy beige. Avoid tints where possible, unless the original is
a tinted mortar, and when using tints use mineral (not organic) tints.
More exotic approach would be to determine the color of the original
aggregate and the matrix (cement/tint) to come up with a very subtle
mortar mix, particularly when weathered (patinated) say a dark coffee
brown aggregate (Brooklyn Greenpoint Shipyards variety) with Rosendale
natural cement with a hint of red tint.
We were doing a repoint job on the Episcopal Church of Ascension in
Brooklyn, near to where the Monitor was built, and we had to go to great
lengths to match the aggregate. Purchasing it in NJ by the bag. Note:
most sand in Manhattan repoint jobs comes by the bag. Along during the
project we had to do some work to re-route the site drainage and on
digging a hole in the areaway found tons of the really nice sand that we
were paying mucho bucks per pound for, plus time & cost of driver to go
to NJ to get same. Lesson learned? Consider the history of the site and
be prepared to dig a hole to look for sand for the mortar (Occam's Razor
once again). But, of course, this is where you have a situation that
accepts the First Ingredient above.
][<en
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