Eric,

IMHO in NYC a 1:1:6 Portland:Type S lime, mason's sand works just fine 
in most situations as 1) it can be purchased today without special order 
and thrown in the PU truck just fine, 2) all the repointers know what 
they are working with so we do not have to re-educate them, 3) in most 
cases it won't make any significant difference to the structural 
integrity of the building, and 4) you as the architect may be able to 
sleep because you have a clear context as to the expected performance - 
even if it is not perfect - and hopefully your client is happy and pays 
their bill. Notwithstanding that there are specific structures of 
heritage value where an authenticity is desired to be maintained and/or 
cases where the original materials are very much more appropriate for 
structural and performance reasons.

I have had situations, no conservators in sight, where we have opened up 
masonry and then scratched our heads trying to figure out why the mortar 
is a strange color of blue and hard as iron. Sometimes only god knows 
what was used in the past. I have also had situations where the 
conservator (expert) has stood there and told me it was impossible that 
the Guastavino tile vault could have been built in the manner we are 
telling them because, as they said, in all of their research at Avery 
they never found any documentation that showed this type of 
construction. Then a little bit further investigation reveals that it 
was built in the unorthodox manner that we suggested.

I would refuse to repoint the Brooklyn Bridge w/ a 1:1:6 Type N mortar. 
And where the opportunity arises that it is appropriate I want to have 
the capacity and in-field technology (good learning mechanics) to 
provide natural cement or lime putty mortars. I can't wait for an 
opportunity to build tile vaults (wine cellars included) with natural 
cement.

Conservators are constantly in a process of extending their field of 
knowledge. They should very well know about natural cements as well as 
other types of traditional and non-traditional mortar mixes. As to the 
mortar analysis it is questionable considering a client's money to what 
extent they want, will pay for, or care about more than a superficial 
analysis that provides a reasonably available and nearly appropriate 
design mix.

I was complaining last week about an architect who specified the mix of 
5 different sands in a mortar, sands from different suppliers, in order 
to obtain a very specific proportion of sizes of sands in the mortar 
recipe. It can all get out of hand rather quickly. Matters were 
compounded by the fact that the new hire on the job from Queens who said 
he was a mason's helper did not know that you put anything besides water 
in with the sand in the mixer. He was using a non-cement mortar... which 
I suppose goes along with the least invasive mortar you can get. Which 
of these problems is the more important one?

If conservation of the built environment is made too complicated or 
prohibitive in cost and detracts from developer investment then it will 
not be conserved.

I'm done with breakfast now... cya later, back to work.

][<

Hammarberg, Eric wrote:

>So guys and gals,
>I work here in olde NYC mostly on late 19th and early 20th century buildings
>and many are fairly significant local buildings.
>

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