Met History wrote:

> "Overcleaning" is a term that often occurs to me when I look at
> building projects.   Sometimes I see it when I see the wide brush
> marks used to apply the original detergent/nuclear material/cleaning
> agent.
>
> But other times I see it when the deep, almost transparent grain of
> the stone is flatted out.   What exactly is that second thing?   And
> does it vanish after a while (as I think it does), or is it permanent?
>  Is overcleaning simply a too-aggressive removal of direct (= patina)?
>  Or is it something beyond dirt?
>
> Christopher "Had A Friend Who Cut The Rear Legs Off Of Lizards And Put
> An Axle Through Them For Fun But Then They Died" Gray

Overcleaning = too strong of an acid, or left on too long before rinsed,
used on sandstone will cut the sheen on the quartz crystals. Same like
if you put acid on glass it will leave a white haze. Or, on mortar or
cementitious elements, the aggregate/sand is quartz. Wide brush marks is
not over cleaning as much as lazy or improper cleaning. If they took
more time and patience with their work then you would not see the brush
marks. Always somethig of a hassle in any cleaning project. Once "burnt"
always burnt. It appears to go away because I think that the surface
area of an etched material is larger than the original and so configured
physically to hold dirt more easily... so the surface gets dirty faster
in a cleaner world. Overcleaning in my mind is when there is significant
destruction to the actual surface of the material being cleaned to the
extent that it goes against the histo presto maxim, "do no harm", as
opposed to "simply removing dirt." All cleaning occurs in a tension
between just enough and over. The predominance of overcleaning has to do
with the difficulty of knowing where the line is and how to best get
there without doing damage. This is why conservators are very very
important... they are the ones who first see the line and they then have
to figure out how to communicate the line into technique and field
application.

It occurs to me that a lot of masonry cleaning has to do with good
reasons, but also often with the way in which our society views building
materials... I believe that there is a progression towards homogenous
appearance of materials, particularly manufactured ones, and that the
aesthetic is to clean older materials, often materials with unique
natural character, until they fit an aesthetic of the "modern", with an
attempt through cleaning to erase the unique character... to make it
look new not in the sense of it was new 100 years ago, but to try to
make it look new like last week.

As with working on the areaway balustrade walls of the House of Fifteen
Bathrooms I am intrigued by the number of campaigns of patching that
have occured in such a small area. Some ot the patches show real skill
and ingenuity, others are obviously terrible, others even yet looking
terribly terrible may at one time have matched one or another of the
coatings. The self-same coating removes from one patching material, but
then is stubborn on another patching material. As I study this small
area trying to figure out what to do next, or not do, I cannot help but
wonder who, how, or why various patches or layers were applied. I want
to leave the better of the patches and not remove them. If we remove all
of the patches there will be nothing left to mend as there is not enough
brownstone in the piece to hold it's own weight.

By the by... the reason the "native" Adami stucco carvers run away from
inquiring minds is that they are all working for cash.

][<en

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