Usually, an abrasive cleaning method is selected as an expeditious
means of quickly removing years of dirt accumulation, unsightly
stains, or deteriorating building fabric or finishes, such as
stucco or paint.
 Brick molding next to the window has been severely abraded by sandblasting to remove paint. Photo: NPS files. |
The fact that sandblasting is one of the best
known and most readily available building cleaning treatments
is probably the major reason for its frequent use.
Many mid-19th century brick buildings were painted immediately
or soon after completion to protect poor quality brick or to imitate
another material, such as stone. Sometimes brick buildings were
painted in an effort to produce what was considered a more harmonious
relationship between a building and its natural surroundings.
By the 1870s, brick buildings were often left unpainted as mechanization
in the brick industry brought a cheaper pressed brick and fashion
decreed a sudden preference for dark colors. However, it was still
customary to paint brick of poorer quality for the additional
protection the paint afforded.
It is a common 20th century misconception that all historic masonry
buildings were initially unpainted. If the intent of a modern
restoration is to return a building to its original appearance,
removal of the paint not only may be historically inaccurate,
but also harmful. Many older buildings were painted or stuccoed
at some point to correct recurring maintenance problems caused
by faulty construction techniques, to hide alterations, or in
an attempt to solve moisture problems. If this is the case, removal
of paint or stucco may cause these problems to reoccur.
Another reason for paint removal, particularly in rehabilitation
projects, is to give the building a "new image" in response
to contemporary design trends and to attract investors or tenants.
Thus, it is necessary to consider the purpose of the intended
cleaning. While it is clearly important to remove unsightly stains,
heavy encrustations of dirt, peeling paint or other surface coatings,
it may not be equally desirable to remove paint from a building
which originally was painted. Many historic buildings which show
only a slight amount of soil or discoloration are much better
left as they are.
A thin layer of soil is more often protective
of the building fabric than it is harmful, and seldom detracts
from the building's architectural and/or historic character. Too
thorough cleaning of a historic building may not only sacrifice
some of the building's character, but also, misguided cleaning
efforts can cause a great deal of damage to historic building
fabric. Unless there are stains, graffiti or dirt and pollution
deposits which are destroying the building fabric, it is generally
preferable to do as little cleaning as possible, or to repaint
where necessary. It is important to remember that a historic building
does not have to look as if it were newly constructed to be an
attractive or successful restoration or rehabilitation project.
"Dangers of Abrasive Cleaning" an Historic Preservation Brief
