Lead in Historic Paints
Lead compounds were an important component of many historic paints.
Lead, in the forms of lead carbonate and lead oxides, had excellent adhesion,
drying, and covering abilities. White lead, linseed oil, and inorganic
pigments were the basic components for paint in the 18th, 19th, and early
20th centuries.
 Significant architectural finishes should not be removed during a project incorporating lead hazard controls. Clear protective coatings may be added by conservators to areas subject to impact or abrasion. Photo: NPS files. |
Lead-based paint was used extensively on wooden exteriors
and interior trimwork, window sash, window frames, baseboards, wainscoting,
doors, frames, and high gloss wall surfaces such as those found in kitchens
and bathrooms. Almost all painted metals were primed with red lead or painted
with lead-based paints. Even milk (casein) and water-based paints (distemper
and calcimines) could contain some lead, usually in the form of hiding
agents or pigments. Varnishes sometimes contained lead. Lead compounds
were also used as driers in paint and window glazing putty.
In 1978, the use of lead-based paint in residential housing was banned
by the federal government. Because the hazards have been known for some
time, many lead components of paint were replaced by titanium and other
less toxic elements earlier in the 20th century. Since houses are periodically
repainted, the most recent layer of paint will most likely not contain
lead, but the older layers underneath probably will. Therefore, the only
way to accurately determine the amount of lead present in older paint is
to have it analyzed.
It is important that owners of historic properties be aware that layers
of older paint can reveal a great deal about the history of a building
and that paint chronology is often used to date alterations or to document
decorative period colors. Highly significant decorative
finishes, such as graining, marbleizing, stenciling, polychrome decoration,
and murals should be evaluated by a painting conservator to develop the
appropriate preservation treatment that will stabilize the paint and eliminate
the need to remove it. If such finishes must be removed in the process
of controlling lead hazards, then research, paint analysis, and documentation
are advisable as a record for future research and treatment.
"Appropriate Methods for Reducing Lead Paint Hazards" an Historic Preservation Brief
