First of all, let's try to define the surface of the doors -- they are
corroded now, not patinated.  They probably were patinated originally, but
lack of maintenance and the insults of salting and who knows what else, have
probably obliterated most, if not all, of the original finish.

Bronzes, unlike unalloyed copper, typically lose surface material as they
weather and deteriorate to that  mottled green and black surface.  These
green compounds are not a "protective patina" as was found on the Statue of
Liberty, for instance; they are water-soluble and wash away in the rain.

There is a chance that a hidden location or two may still reveal an idea of
the original patination, which often was a warm brown color or "statuary"
finish.  (See unweathered objects inside museums.)  The term "patination" in
reference to objects such as these doors and other architectural and
artistic bronzes,  should be considered as a purposeful, artificial
coloration of the surface of the metal, induced by the application of
chemicals, often catalyzed by heating the metal during application.  This
coloration is a "patina", it is not a coating, it is chemically altered
metal -- and it should be protected by maintainable, renewable coatings such
as lacquers and waxes.

I definitely think that a good metals conservator should be called in.
There are several here in the city and nearby that do this kind of work.
One or two "contractors" also may have this capability, but please stay away
from the Remco/StuartDean types -- this is out of their league.

Hope this helps.

Bruce Popkin



> -----Original Message-----
> From: Met History [SMTP:[log in to unmask]]
> Sent: Thursday, April 19, 2001 6:54 PM
> To:   [log in to unmask]
> Subject:      Preservation question: clean facade, but leave the bronze?
>
> Carrere & Hastings designed a  1909 townhouse at 69 East 79th Street (NYC)
> for George Rives, now occupied by the Greek consulate.  The Consul General
> has just finished cleaning the limestone facade and installing new/old
> white
> windows.  But, on the stoop, he pointing to the anciently-patinaed bronze
> doors (also 1909) and said "Do I clean them, like we cleaned the facade?
> Then they'll just look new."
>
> He had three test areas:
> 1.  completely refinished to look nearly black
> 2.   completely refinished to look bright
> 3.   slightly polished, to yield some highlights, but leaving mostly
> deeper
> "bronze" color on the low points
> 4.    untouched, which mixes the deep green patina with salt spray and
> accumulated crud
>
> Then he pointed to the small area which people push to get into the
> building,
> rubbed smooth, with that red tint that is native to old bronze.  He
> pointed
> to that area and said "That, that's what I want - but how can I get that?"
>
> What should I have told him?
>
> Christopher Gray