Moravian Preservation Master Plan.indb - Society for College and ...

Moravian College • Preservation Master Plan
painting these metals. However, alkyd-based rust
inhibitive primers should be used to protect the
substrate since modern alkyd paints tend to go on
thinner than traditional coatings. Zinc-rich primers
will provide a more durable finish, but they can only
be applied over clean metal; they are only suitable
for shop-prepared metalwork. Copper, bronze, and
stainless steel should be left exposed.
Painted and Varnished Woodwork
Retain and renew paint coatings on wood features
that have been painted in the past; paint helps to
protect the surface from moisture and light damage.
Paint that is firmly adhered should be left in place
and not removed unless it is failing. If all paint is
planned for removal during a rehabilitation project,
samples of the existing layers of color should be
taken prior to complete removal. This is used to
perform a paint analysis that records the historic
sequence of colors.
Many of the main entrance doors have been finished
with a colored varnish or with a stain and clear
varnish coating. Shellac or oil-based varnishes were
traditionally used to protect woodwork up through
the post-World War II era. Many of these exterior
doors may have been refinished with modern
polyurethane varnishes. It is important to identify
the existing varnish coating prior to refinishing.
Shellac varnishes can often be refreshed using
mineral spirits and new shellac. Oil-based varnishes
can be removed with solvents and renewed.
However, polyurethane coatings require complete
removal down to bare wood. The wood will need to
be re-stained and varnished. Polyurethane coatings
should be applied by a skilled contractor to avoid
lap marks, bubbling, and super high gloss finishes.
Painted Stucco
Traditionally, stucco was integrally colored through
the use of colored aggregate and the addition of
lime-stable pigments in the finish coat mix. In
the nineteenth century, stucco was also routinely
whitewashed. These early coatings were later
replaced by modern paints as the commercial
paint industry expanded circa 1875. Stucco that
has been painted should continue to be coated.
Appropriate coatings include lime and cement
paints, latex paints, and alkyd paints. Paint type
will be determined by the previous coatings; new
paint must be compatible with existing coatings.
Unpainted Surfaces
Do not paint masonry or stucco that has never been
painted. Painting undamaged masonry surfaces is
not a preservation treatment. This is unnecessary
unless the surface is much deteriorated from extreme
weathering, water penetration, or sandblasting and
other abrasive treatments. Do not paint windows
shut or coat the window glass.
Repair and Repainting
Before removing, handling, or disposing of paint,
it is critical to determine if it is lead-based. Most
paints installed prior to 1978 can be assumed
to contain lead. If properly encapsulated with
modern, non-lead containing paints, the earlier
lead paint layers are not typically considered a
hazard. A higher level of scrutiny is required in
areas where children are present, on friction and
impact surfaces, and where the paint is severely
deteriorated. It is critical to follow best protection
practices when scraping or sanding surfaces that
have been painted with lead-based paints. Ensure
that the removal process complies with local, state,
and federal laws and avoid breathing or ingesting
the dust of lead-based paint.
Use the gentlest means possible to remove paint and
only remove deteriorated paint layers. For buildings
with extensively deteriorated paint, remove all
unstable coatings to bare substrate after sampling
and recording the historic paint color sequence.
Architectural features should not be stripped and
left bare. The unprotected substrate will quickly
discolor and deteriorate; metal substrates will
quickly corrode.
Hand-scraping and hand-sanding is the best
technique for removing paint on some historical
materials. Limited and judicious use of chemical
strippers can be considered, provided test patches
are evaluated prior to large-scale stripping. Care
should be taken that chemical strippers do not
damage adjacent building or landscape materials.
Alkaline chemicals should be approached with
caution when removing paint from wood substrates;
they raise the grain and can easily damage wood.
In contrast, alkaline paint strippers have proven
to be the most effective type of stripper for use on
iron-containing metals. On masonry, mild chemical
strippers may be appropriate but only under skilled
supervision with prior test patches. It is important
to ensure that chemicals are thoroughly rinsed
John Milner Associates • October 2009 • Chapter 9 • Building Guidelines • 311