Where exterior surface conditions have been identified that warrant
total paint removal such as peeling, cracking, or alligatoring,
two thermal devices the electric heat plate and the electric
heat gun have proven to be quite successful for use on
different wooden elements of the historic building. One thermal
method the blow torch is not recommended because
it can scorch the wood or even burn the building down!
Electric heat plate: The electric heat plate operates
between 500 and 800 degrees Fahrenheit (not hot enough to vaporize
lead paint), using about 15 amps of power. The plate is held
close to the painted exterior surface until the layers of paint
begin to soften and blister, then moved to an adjacent location
on the wood while the softened paint is scraped off with a putty
knife (it should be noted that the heat plate is most successful
when the paint is very thick!).
With practice, the operator can successfully move the heat
plate evenly across a flat surface such as wooden siding or
a window sill or door in a continuous motion, thus lessening
the risk of scorching the wood in an attempt to reheat the edge
of the paint sufficiently for effective removal.
Since the electric heat plate's coil is "red hot,"
extreme caution should be taken to avoid igniting clothing or
burning the skin. If an extension cord is used, it should be
a heavy-duty cord (with three-prong grounded plugs). A heat
plate could overload a circuit or, even worse, cause an electrical
fire; therefore, it is recommended that this implement be used
with a single circuit and that a fire extinguisher always
be kept close at hand.
Electric heat gun: The electric heat gun (electric hot-air
gun) looks like a handheld hairdryer with a heavyduty metal
case. It has an electrical resistance coil that typically heats
between 500 and 750 degrees Fahrenheit and, again, uses about
15 amps of power which requires a heavy-duty extension cord.
There are some heat guns that operate at higher temperatures
but they should not be purchased for removing old paint because
of the danger of lead paint vapors. The temperature is
controlled by a vent on the side of the heat gun. When the vent
is closed, the heat increases. A fan forces a stream of hot
air against the painted woodwork, causing a blister to form.
At that point, the softened paint can be peeled back with a
putty knife. It can be used to best advantage when a paneled
door was originally varnished, then painted a number of times.
In this case, the paint will come off quite easily, often leaving
an almost pristine varnished surface behind.
Like the heat plate, the heat gun works best on a heavy paint
buildup. (It is, however, not very successful on only one or
two layers of paint or on surfaces that have only been varnished.
The varnish simply becomes sticky and the wood scorches.)
Although the heat gun is heavier and more tiring to use than
the heat plate, it is particularly effective for removing paint
from detail work because the nozzle can be directed at curved
and intricate surfaces. Its use is thus more limited than
the heat plate, and most successfully used in conjunction with
the heat plate. For example, it takes about two to three hours
to strip a paneled door with a heat gun, but if used in combination
with a heat plate for the large, flat area, the time can usually
be cut in half. Although a heat gun seldom scorches wood, it
can cause fires (like the blow torch) if aimed at the dusty
cavity between the exterior sheathing and siding and interior
lath and plaster. A fire may smolder for hours before flames
break through to the surface. Therefore, this thermal device
is best suited for use on solid decorative elements, such as
molding, balusters, fretwork, or "gingerbread."
Blow Torch: Blow torches, such as handheld propane or
butane torches, were widely used in the past for paint removal
because other thermal devices were not available. With this
technique, the flame is directed toward the paint until it begins
to bubble and loosen from the surface. Then the paint is scraped
off with a putty knife. Although this is a relatively fast process,
at temperatures between 3200 and 3800 degrees Fahrenheit the
open flame is not only capable of burning a careless operator
and causing severe damage to eyes or skin, it can easily scorch
or ignite the wood.
The other fire hazard is more insidious. Most frame buildings
have an air space between the exterior sheathing and siding
and interior lath and plaster. This cavity usually has an accumulation
of dust which is also easily ignited by the open flame of a
blow torch. Finally, lead-base paints will vaporize at high
temperatures, releasing toxic fumes that can be unknowingly
inhaled. Therefore, because both the heat plate and the heat
gun are generally safer to use that is, the risks are
much more controllable the blow torch should definitely
Recommended: Electric heat plate, electric heat gun.
Applicable areas of building: Electric heat plate--flat surfaces
such as siding, eaves, sash, sills, doors. Electric heat gun--solid
decorative molding, balusters, fretwork, or "gingerbread."
For use on: Class III conditions.
Health/Safety factors: Take precautions against eye damage and
fire. Dispose of lead paint residue properly.
Not Recommended: Blow torch.