At the outset of this Brief, it must be emphasized that removing
paint from historic buildings--with the exception of cleaning,
light scraping, and hand sanding as part of routine maintenance--should
be avoided unless absolutely essential. Once conditions warranting
removal have been identified the general approach should be to
remove paint to the next sound layer using the gentlest means
possible, then to repaint. Practically speaking
as well, paint can adhere just as effectively to existing paint
as to bare wood, providing the previous coats of paint are also
adhering uniformly and tightly to the wood and the surface is
properly prepared for repainting-- cleaned of dirt and chalk and
dulled by sanding.
But, if painted exterior wood surfaces display
continuous patterns of deep cracks or if they are extensively
blistering and peeling so that bare wood is visible, then the
old paint should be completely removed before repainting. The
only other justification for removing all previous layers of paint
is if doors, shutters, or windows have literally been "painted
shut," or if new wood is being pieced-in adjacent to old painted
wood and a smooth transition is desired.
Because paint removal is a difficult and painstaking process,
a number of costly, regrettable experiences have occurred--and
continue to occur--for both the historic building and the building
owner. Historic buildings have been set on fire with blow torches;
wood irreversibly scarred by sandblasting or by harsh mechanical
devices such as rotary sanders and rotary wire strippers; and
layers of historic paint inadvertently and unnecessarily removed.
In addition, property owners, using techniques that substitute
speed for safety, have been injured by toxic lead vapors or dust
from the paint they were trying to remove or by misuse of the
paint removers themselves.
Owners of historic properties considering paint removal should
also be aware of the amount of time and labor involved. While
removing damaged layers of paint from a door or porch railing
might be readily accomplished within a reasonable period of time
by one or two people, removing paint from larger areas of a building
can, without professional assistance, easily become unmanageable
and produce less than satisfactory results. The amount of work
involved in any paint removal project must therefore be analyzed
on a case-by-case basis. Hiring qualified professionals will often
be a cost-effective decision due to the expense of materials, the
special equipment required, and the amount of time involved. Further,
paint removal companies experienced in dealing with the inherent
health and safety dangers of paint removal should have purchased
such protective devices as are needed to mitigate any dangers
and should also be aware of State or local environmental and/or
health regulations for hazardous waste disposal.
All in all, paint removal is a messy, expensive, and potentially
dangerous aspect of rehabilitating or restoring historic buildings
and should not be undertaken without careful thought concerning
first, its necessity, and second, which of the available recommended
methods is the safest and most appropriate for the job at hand.
If existing exterior paint on wood siding, eaves, window sills,
sash, and shutters, doors, and decorative features shows no evidence
of paint deterioration such as chalking, blistering, peeling,
or cracking, then there is no physical reason to repaint, much
less remove paint! Nor is color fading, of itself, sufficient
justification to repaint a historic building.
The decision to repaint may not be based altogether on paint failure.
Where there is a new owner, or even where ownership has remained
constant through the years, taste in colors often changes. Therefore,
if repainting is primarily to alter a building's primary and accent
colors, a technical factor of paint accumulation should be taken
into consideration.
When the paint on the wood windows became too thick, it was removed and the window repainted. Photo: NPS files.
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When paint builds up to a thickness of approximately
1/16" (approximately 16 to 30 layers), one or more extra coats of
paint may be enough to trigger cracking and peeling in limited
or even widespread areas of the building's surface. This results
because excessively thick paint is less able to withstand the
shrinkage or pull of an additional coat as it dries and is also
less able to tolerate thermal stresses. Thick paint invariably
fails at the weakest point of adhesion--the oldest layers next
to the wood. Cracking and peeling follow. Therefore, if there
are no signs of paint failure, it may be somewhat risky to add
still another layer of unneeded paint simply for color's sake
(extreme changes in color may also require more than one coat
to provide proper hiding power and full color). When paint appears
to be nearing the critical thickness, a change of accent colors
(that is, just to limited portions of the trim) might be an acceptable
compromise without chancing cracking and peeling of paint on wooden
siding.
If the decision to repaint is nonetheless made, the "new"
color or colors should, at a minimum, be appropriate to the style
and setting of the building. On the other hand, where the intent
is to restore or accurately reproduce the colors originally used
or those from a significant period in the building's evolution,
they should be based on the results of a paint analysis.