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Historic Preservation - Technical Procedures

Spectitle:

Preservation Briefs: 37 Appropriate Methods For Reducing Lead-Paint Hazards In Historic Masonry

Procedure code:

0990004S

Source:

National Park Service

Division:

Finishes

Section:

Painting

Last Modified:

09/05/2012

Details:

Preservation Briefs: 37 Appropriate Methods For Reducing Lead-Paint Hazards In Historic Masonry



PRESERVATION BRIEFS: 37

APPROPRIATE METHODS FOR REDUCING LEAD-PAINT HAZARDS IN HISTORIC
HOUSING

The link immediately below connects with the latest version of National Park Service's Preservation Brief 37:

 

http://www.nps.gov/history/hps/tps/briefs/brief37.htm

 


Sharon C. Park, AIA and Douglas C. Hicks

This standard includes the bulk of information contained in the
original Preservation Brief developed by the National Park Service.
To obtain a complete copy of this brief, including figures and
illustrations, please contact:  

              Superintendent of Documents
              P.O. Box 371954
              Pittsburgh, PA  15250-7954

              GPO #024-005-01121-8
              $1.50

Please call the Publication Order Information Desk at 202/783-3238
or FAX 202/512-2250 to verify price and availability.  


THE SECRETARY OF THE INTERIOR'S "STANDARDS FOR HISTORIC
PRESERVATION PROJECTS" EMBODY TWO IMPORTANT GOALS: 1) THE
PRESERVATION OF HISTORIC MATERIALS AND, 2) THE PRESERVATION OF A
BUILDING'S DISTINGUISHING CHARACTER.  EVERY OLD BUILDING IS UNIQUE,
WITH ITS OWN IDENTITY AND ITS OWN DISTINCTIVE CHARACTER.  CHARACTER
REFERS TO ALL THOSE VISUAL ASPECTS AND PHYSICAL FEATURES THAT
COMPRISE THE APPEARANCE OF EVERY HISTORIC BUILDING.


***INTRODUCTION***

Lead-based paint, a toxic material, was widely used in North
America on both the exteriors and interiors of buildings until well
into the second half of the twentieth century. If a 'historic'
place is broadly defined in terms of time as having attained an age
of fifty years, this means that almost every historic house
contains some lead-base paint. In its deteriorated form, it
produces paint chips and lead-laden dust particles that are a known
health hazard to both children and adults. Children are
particularly at risk when they ingest lead paint dust through
direct hand-to-mouth contact and from toys or pacifiers. They are
also at risk when they chew lead-painted surfaces in accessible
locations. In addition to its presence in houses, leaded paint
chips, lead dust, or lead-contaminated soil in play areas can
elevate a child's blood level to a degree so that measures to
reduce and control the hazard should be undertaken.

ACTION LEVELS:

Readers should become familiar with terminology and basic levels
that trigger concern and/or action. Check with the appropriate
authorities if you have questions and to verify applicable action
levels which may change over time.

BLOOD LEAD LEVELS: Generally from drawn blood and not a finger
stick test which can be unreliable. Units are measured in
micrograms per deciliter (ug/dl) and reflect the 1995 standards
from the Centers for Disease Control.

Children: 10 ug/dl; level of concern; find source of
         lead
         15 ug/dl and above; intervention, counseling,
         medical monitoring
         25 ug/dl and above; medical treatment
Adults:   25 ug/dl; level of concern; find source of
         lead
         50 ug/dl; OSHA standard for medical removal
         from the worksite

LEAD IN PAINT: Differing methods report results in differing units.
Lead is considered a potential hazard if ABOVE THE FOLLOWING
LEVELS, but can be a hazard at lower levels, if improperly handled.
These are the current numbers as identified by the Department of
Housing and Urban Development (1995).

Lab Analysis of Samples:
         5,000 milligram per kilogram (mg/kg) or 5,000
         parts per million (ppm), or
         0.5% lead by weight.

XRF Reading: In milligram per centimeter squared
         1 mg/cm2

Lead Dust Wipe Test: In micrograms per square foot

    Floors              100 ug/ft2
    Window Sills        500 ug/ft2
    Window Troughs      800 ug/ft2

Lead in Soil: High contact bare play areas, listed as parts per
million (ppm):

    Concern             400 ppm
    Interim Control     2,000 ppm
    Hazard Abatement    5,000 ppm

The premise of this Preservation Brief is that historic housing can
be made lead-safe for children without removing significant
decorative features and finishes, or architectural trimwork that
may contribute to the building's historic character. Historic
housing -- encompassing private dwellings and all types of rental
units -- is necessarily the focus of this Brief because Federal and
state laws primarily address the hazards of lead and lead-based
paint in housing and day-care centers to protect the health of
children under six years of age. Rarely are there mandated
requirements for the removal of lead-based paint from non-
residential buildings.

Ideally, most owners and managers should understand the health
hazards created by lead-based paint and voluntarily control these
hazards to protect young children. A stricter approach has been
taken by some state and Federal funding programs which have
compliance requirements for identifying the problem, notifying
tenants, and, in some cases, remedying lead hazards in housing.
With new rules being written, and new products and approaches being
developed, it is often difficult to find systematic and balanced
methodologies for dealing with lead-based paint in historic
properties.

This Preservation Brief is intended to serve as an introduction to
the complex issues of historic lead-based paint and its management.
It explains how to plan and implement lead-hazard control measures
to strike a balance between preserving a historic building's
significant materials and features and protecting human health and
safety, as well as the environment. It is not meant to be a 'how-
to-guide' for undertaking the work. Such a short-cut approach could
easily result in creating a greater health risk, if proper
precautions were not taken. Home renovators and construction
workers should be aware that serious health problems can be caused
by coming into contact with lead. For this reason, there are also
laws to protect workers on the job site. Controlling the amount of
waste containing lead-based paint residue will also reduce the
impact on the environment. All of these considerations must be
weighed against the goal of providing housing that is safe for
children.

LEAD-BASED PAINT LEGISLATION:

The following summarizes important regulations that affect lead-
hazard reduction projects. Owners should be aware that regulations
change and they have a responsibility to check state and local
ordinances as well.

Federal Legislation:
Title X (Ten) Residential Lead-Based Paint Hazard Reduction Act of
1992 is part of the Housing and Community Development Act of 1992
(Public Law 102-550). It established that HUD issue The Guidelines
for the Evaluation and Control of Lead-Based Paint Hazards in
Housing (1995) to outline risk assessments, interim controls, and
abatement of lead-based paint hazards in housing. Title X calls for
the reduction of lead in housing that is Federally supported and
outlines the Federal responsibility towards its own residential
units and the need for disclosure of lead in residences, even
private residences, prior to sale.

Interim Final Regulations of Lead in Construction Standards (29CFR
1926.62). Issued by Department of Labor, Occupational Safety and
Health Administration (OSHA), these regulations address worker
safety, training, and protective measures. It is based in part on
environmental air sampling to determine the amount of lead dust
generated by various activities.

Toxic Substance Control Act; Title IV. The Environmental Protective
Agency (EPA) has jurisdiction for setting standards for lead
abatement. Also, EPA controls the handling and disposal of
hazardous waste generated during an abatement project. EPA will
develop standards to establish lead hazards, to certify abatement
contractors, and to establish work practice standards for abatement
activity. EPA Regional Offices can provide guidance on the
appropriate regulatory agency for states within their region.

State Laws:
States generally have the authority to regulate the removal and
transportation of lead-based paint and the generated waste
generally through the appropriate state environmental and public
health agencies. Most requirements are for mitigation in the case
of a lead-poisoned child, or for protection of children, or for
oversight to ensure the safe handling and disposal of lead waste.
When undertaking a lead-based paint reduction program, it is
important to determine which laws are in place that may affect your
project. Call the appropriate officials.

Local Ordinances:
Check with local health departments, Poison Control Centers, and
offices of housing and community development to determine if there
are laws that require compliance by building owners. Rarely are
owners required to remove lead-based paint and most laws are to
ensure safety if a project is undertaken as part of a larger
rehabilitation. Special use permits may be required when an
environmental impact may occur due to a cleaning treatment that
could contaminate water or affect water treatment. Determine
whether projects are considered abatements and will require special
contractors and permits.

Owner's Responsibility:
Owners are ultimately responsible for ensuring that hazardous waste
is properly disposed of when it is generated on their own sites.
Owners should check with their state office to determine if the
abatement project requires a certified contractor. (National
certification requirements are not yet in place.) Owners should
establish that the contractor is responsible for the safety of the
crew and that all applicable laws are followed, and that
transporters and disposers of hazardous waste have liability
insurance as a protection for the owner. If an interim treatment is
being used to reduce lead hazards, the owner should notify the
contractor that lead-based paint is present and that it is the
contractor's responsibility to follow appropriate work practices to
protect workers and to complete a thorough clean-up to ensure that
lead-laden dust is not present after the work is completed.

WORKER SAFETY:

Current worker safety standards were established by OSHA's 29 CFR
Part 1926, Lead Exposure in Construction; Interim Final Rule, which
became effective June 3, 1993. These standards base levels of
worker protection on exposure to airborne lead dust. They are
primarily targeted to persons working within the construction
industry, but apply to any workers who are exposed to lead dust for
longer than a specific amount of time and duration. The Interim
Final Rule establishes an action level of 30 micrograms of lead
dust per cubic meter of air (30 ug/m  3 ) based on an eight hour,
time-weighted average, as the level at which employers must
initiate compliance activities; and it also establishes 50 ug/m 3of lead dust as the permitted exposure level (PEL) for workers.

The standard identifies responsibilities before, during, and after
the actual abatement activity necessary to protect the worker.
Before the project begins, it requires an exposure assessment, a
written compliance plan, initial medical surveillance, and
training. The exposure assessment determines whether a worker may
be exposed to lead. OSHA has identified a number of work tasks
expected to produce dust levels between 50 and 500 ug/m 3 of air,
including manual demolition, manual scraping, manual sanding, heat
gun applications, general cleanup, and power tool use when the
power tool is equipped with a dust collection system. It is an OSHA
requirement that, at a minimum, a HEPA filtered half-face
respirator with a protection factor of 10 be used for these
operations. Initial blood lead level (BLL) base lines are
established for each worker. Actual dust levels are monitored by
air sampling of representative work activities, generally by an
industrial hygienist or an environmental monitoring firm.
Protective equipment is determined by the dust level. For all
workers exposed at, or above, the action level for over thirty days
in a 12-month period, BLLs are tested on a regular basis of every
two months for the first six months and every six months
thereafter. After completing a project, maintenance, medical
surveillance, and record-keeping responsibilities continue.

HEPA vacuums, HEPA respirators, and HEPA filters, which
substantially reduce exposure to lead dust, are available through
laboratory safety and supply catalogs and vendors.

Copies of 29 CFR Part 1926, Lead Exposure in Construction: Interim
Final Rule, are available from the Department of Labor,
Occupational Safety and Health Administration, or may be found in
any library with a current edition of the Code of Federal
Regulation (CFR).

This Preservation Brief is intended to serve as an introduction to
the complex issue of historic lead-based paint and its management.
It explains how to plan and implement lead-hazard control measures
to strike a balance between preserving a historic building's
significant materials and features and protecting human health and
safety, as well as the environment. It is not meant to be a 'how-
to-guide' for undertaking the work. Such a short-cut approach could
easily result in creating a greater health risk, if proper
precautions were not taken. Home renovators and construction
workers should be aware that serious health problems can be caused
by coming into contact with lead. For this reason, there are also
laws to protect workers on the job site. Controlling the amount of
waste containing lead-based paint residue will also reduce the
impact on the environment. All of these considerations must be
weighed against the goal of providing housing that is safe for
children.


***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 pain in the
18th, 19th, and early 20th centuries. 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.


***PLANNING FOR LEAD HAZARD REDUCTION IN HISTORIC HOUSING***

Typical health department guidelines call for removing as much of
the surfaces that contain lead-based paint as possible. This
results in extensive loss or modification of architectural features
and finishes and is not appropriate for most historic properties.
A great number of Federally-assisted housing programs are moving
away from this approach as too expensive and too dangerous to the
immediate work environment. A preferred approach, consistent with
The Secretary of the Interior's Standards for the Treatment of
Historic Properties, calls for removing, controlling, or managing
the hazards rather than wholesale -- or even partial -- removal of
the historic features and finishes. This is generally achieved
through careful cleaning and treatment of deteriorating paint,
friction surfaces, surfaces accessible to young children, and lead
in soil. Lead-based paint that is not causing a hazard is thus
permitted to remain, and, in consequence, the amount of historic
finishes, features and trimwork removed from a property is
minimized.

Because the hazard of lead poisoning is tied to the risk of
ingesting lead, careful planning can help to determine how much
risk is present and how best to allocate available financial
resources. An owner, with professional assistance, can protect a
historic resource and make it lead-safe using this three-step
planning process:

         I.   Identify the historical significance of the
                   building and architectural character of its
                   features and finishes;
         
         II.  Undertake a risk assessment of interior and
              exterior surfaces to determine the hazards
              from lead and lead-based paint; and,
         
         III. Evaluate the options for lead hazard control
              in the context of historic  preservation
              standards.
         
         
    I.   Identify the historical significance of the building and
    architectural character of its features and finishes.

The historical significance, integrity, and architectural character
of the building always needs to be assessed before work is
undertaken that might adversely affect them. An owner may need to
enlist the help of a preservation architect, building conservator
or historian. The State Historic Preservation Office (SHPO) may be
able to provide a list of knowledgeable preservation professionals
who could assist with this evaluation.

Features and finishes of a historic building that exhibit
distinctive characteristics of an architectural style; represent
work by specialized craftsmen; or possess high artistic value
should be identified so they can be protected and preserved during
treatment. When it is absolutely necessary to remove a significant
architectural feature or finish -- as noted in the first two
priorities listed below -- it should be replaced with a new feature
and finish that matches in design, detail, color, texture, and, in
most cases, material.

Finally, features and finishes that characterize simple, vernacular
buildings should be retained and preserved; in the process of
removing hazards, there are usually reasonable options for their
protection. Wholesale removal of historic trim, and other seemingly
less important historic material, undermines a building's overall
character and integrity and, thus, is never recommended.

For each historic property, features will vary in significance. As
part of a survey of each historic property, a list of priorities
should be made, in this order

-    Highly significant features and finishes that should always be
    protected and preserved;

-    Significant features and finishes that should be carefully
    repaired or, if necessary, replaced in-kind or to match all
    visual qualities; and

-    Non-significant or altered areas where removal, rigid
    enclosure, or replacement could occur.

This hierarchy gives an owner a working guide for making decisions
about appropriate methods of removing lead paint.

II.  Undertake a risk assessment of interior and exterior surfaces
    to determine hazards from lead and lead-based paint.

While it can be assumed that most historic housing contains lead-
based paint, it cannot be assumed that it is causing a health risk
and should be removed. The purpose of a risk assessment is to
determine, through testing and evaluation, where hazards from lead
warrant remedial action. Testing by a specialist can be done on
paint, soil, or lead dust either on-site or in a laboratory using
methods such as x-ray fluorescence (XRF) analyzers, chemicals, dust
wipe tests, and atomic absorption spectroscopy. Risk assessments
can be fairly low-cost investigations of the location, condition,
and severity of lead hazards found in house dust, soil, water, and
deteriorating paint. Risk assessments will also address other
sources of lead from hobbies, crockery, water, and the parents'
work environment. A public health office should be able to provide
names of certified risk assessors, paint inspectors, and testing
laboratories. These services are critical when owners are seeking
to implement measures to reduce suspected lead hazards in housing,
day-care center, or when extensive rehabilitations are planned.

The risk assessment should record:

-    the paint's location
-    the paint's condition
-    lead content of paint and soil
-    the type of surface (friction; accessible to children for
    chewing; impact)
-    how much lead dust is actively present
-    how the family uses and cares for the house
-    the age of the occupants who might come into contact with lead
    paint.

It is important from a health standpoint that future tenants,
painters, and construction workers know that lead-based paint is
present, even under treated surfaces, in order to take precautions
when work is undertaken in areas that will generate lead dust.
Whenever mitigation work is completed, it is important to have a
clearance test using the dust wipe method to ensure that lead-laden
dust generated during the work does not remain at levels above
those established by the Environmental Protection Agency (EPA) and
the Department of Housing and Urban Development (HUD). A building
file should be maintained and updated whenever any additional lead
hazard control work is completed.

Hazards should be removed, mitigated, or managed in the order of
their health threat, as identified in a risk assessment (with #1
the greatest risk and #8 the least dangerous):

1.   Peeling, chipping, flaking, and chewed interior lead-based
    paint and surfaces

2.   Lead dust on interior surfaces

3.   High lead in soil levels around the house and in play areas
    (check state requirements)

4.   Deteriorated exterior painted surfaces and features

5.   Friction surfaces subject to abrasion (windows, doors, painted
    floors)

6.   Accessible, chewable surfaces (sills, rails) if small children
    are present

7.   Impact surfaces (baseboards and door jambs)

8.   Other interior surfaces showing age or deterioration (walls
    and ceilings)

III. Evaluate options for hazard control in the context of historic
    preservation standards.

The Secretary of the Interior's Standards for the Treatment of
Historic Properties -- established principles used to evaluate work
that may impact the integrity and significance of National Register
properties -- can help guide suitable health control methods. The
preservation standards call for the protection of historic
materials and historic character of buildings through
stabilization, conservation, maintenance, and repair. The
rehabilitation standards call for the repair of historic materials
with replacement of a character-defining feature appropriate only
when its deterioration or damage is so extensive that repair is
infeasible. From a preservation standpoint, selecting a hazard
control method that removes only the deteriorating paint, or that
involves some degree of repair, is always preferable to the total
replacement of a historic feature.

By tying the remedial work to the areas of risk, it is possible to
limit the amount of intrusive work on delicate or aging features of
a building without jeopardizing the health and safety of the
occupants. To make historic housing lead-safe, the gentlest method
possible should be used to remove the offending substance -- lead-
laden dust, visible paint chips, lead in soil, or extensively
deteriorated paint. Overly aggressive abatement may damage or
destroy much more historic material than is necessary to remove
lead paint, such as abrading historic surfaces. Another reason for
targeting paint removal is to limit the amount of lead dust on the
work site. This, in turn, helps avoid expensive worker protection,
cleanup, and disposal of larger amounts of hazardous waste.

Whenever extensive amounts of lead must be removed from a property,
or when methods of removing toxic substances will impact the
environment, it is extremely important that the owner be aware of
the issues surrounding worker safety, environmental controls, and
proper disposal. Appropriate architectural, engineering and
environmental professionals should be consulted when lead hazard
projects are complex.

Following are brief explanations of the two approaches for
controlling lead hazards, once they have been identified as a risk.
These controls are recommended by the Department of Housing and
Urban Development in Guidelines for the Evaluation and Control of
Lead-Paint Hazards in Housing, and are summarized here to focus on
the special considerations for historic housing:

Interim Controls: Short-term solutions include thorough dust
removal; thorough washdown and clean-up of exposed surfaces; paint
film stabilization and repainting; covering of lead-contaminated
soil; and making tenants aware of lead hazards. Interim controls
require ongoing maintenance and evaluation.

Hazard Abatement: Long-term solutions are defined as having an
expected life of 20 years or more, and involve permanent removal of
hazardous paint through chemicals, heat guns or controlled
sanding/abrasive methods; permanent removal of deteriorated painted
features through replacement; the removal or permanent covering of
contaminated soil; and the use of enclosures (such as drywall) to
isolate painted surfaces. The use of specialized elastomeric
encapsulant paints and coatings can be considered as permanent
containment of lead-based paint if they receive a 20-year
manufacturer's warranty or are approved by a certified risk
assessor. One should be aware of their advantages and drawbacks for
use in historic housing.

Within the context of the historic preservation standards, the most
appropriate method will always be the least invasive. More invasive
approaches are considered only under the special circumstances
outlined in the three-step process. The greatest number of
residential projects fall well within the "interim controls"
section. Most housing can be made safe for children using these
sensitive treatments, particularly if no renovation work is
anticipated. Next, where owners may have less control over the care
and upkeep of housing and rental units, more aggressive means of
removing hazards may be needed. Finally, large-scale projects to
rehabilitate housing or convert non-residential buildings to
housing may successfully incorporate "hazard abatement" as a part
of the overall work.


***APPROPRIATE METHODS FOR CONTROLLING LEAD HAZARDS***

In selecting appropriate methods for controlling lead hazards, it
is important to refer to Step I of the survey where architecturally
significant features and finishes are identified and need to be
preserved. Work activities will vary according to hazard abatement
needs; for example, while an interim control would be used to
stabilize paint on most trimwork, an accessible window sill might
need to be stripped prior to repainting. Since paint on a window
sill is usually not a significant finish, such work would be
appropriate. Other appropriate methods for controlling lead hazards
are summarized in the chart at the conclusion of this Brief.

The method selected for removing or controlling the hazards has a
direct bearing on the type of worker protection as well as the type
of disposal needed, if waste is determined to be hazardous. (See
the chart at the conclusion of this Brief.) Following are examples
of appropriate methods to use to control lead hazards within an
historic preservation context.

HISTORIC INTERIORS (deteriorating paint and chewed surfaces).
Whenever lead-based paint (or lead-free paint covering older
painted surfaces) begins to peel, chip, craze, or otherwise comes
loose, it should be removed to a sound substrate and the surface
repainted. If children are present and there is evidence of painted
surfaces that have been chewed, such as a window sill, then these
surfaces should be stripped to bare wood and repainted. The removal
of peeling, flaking, chalking, and deteriorating paint may be of a
small scale and undertaken by the owner, or may be extensive enough
to require a paint contractor. In either case, care must be taken
to avoid spreading lead dust throughout the dwelling unit. If the
paint failure is extensive and the dwelling unit requires more
permanent hazard removal, then an abatement contractor should be
considered. Many states are now requiring that this work be
undertaken by specially trained and certified workers.

If an owner undertakes interim controls, it would be advisable to
receive specialized training in handling lead-based paint. Such
training emphasizes isolating the area, putting plastic sheeting
down to catch debris, turning off mechanical systems, taping
registers closed, and taking precautions to clean up prior to
handling food. Work clothes should be washed separately from
regular family laundry. The preferred method for removing flaking
paint is the wet sanding of surfaces because it is gentle to the
substrate and controls lead dust. The key to reducing lead hazards
while stabilizing flaking paint is to keep the surfaces slightly
damp to avoid ingesting lead dust. Wet sanding uses special
flexible sanding blocks or papers that can be rinsed in water or
used along with a bottle mister. This method will generally not
create enough debris to constitute hazardous waste.

Other methods for selectively removing more deteriorated paint in
historic housing include controlled sanding, using low-temperature
heat guns, or chemical strippers. Standard safety precautions and
appropriate worker protection should be used. Methods to avoid
include uncontrolled dry abrasive methods, high heat removal (lead
vaporizes at 1100 F), uncontrolled water blasting, and some
chemicals considered carcinogenic (methylene chloride). When
possible and practicable, painted elements, such as radiators,
doors, shutters, or other easily removable items, can be taken to
an off-site location for paint removal.


In most cases, when interior surfaces are repainted, good quality
interior latex or oil-alkyd paints may be used. The paint and
primer system must be compatible with the substrate, as well as any
remaining, well-bonded, paint.

Encapsulant paints and coatings, developed to contain lead-based
paint, rely on an adhesive bonding of the new paint through the
layers of the existing paint. The advantages of these special paint
coatings is that they allow the historic substrate to remain in-
place; reduce the amount of existing paint removed; can generally
be applied without extensive worker protection; and are a durable
finish. (They cannot, however, be used on friction surfaces.) The
as less permanent interim controls.




 


Preservation Brief 37, lead paint, lead paint hazards, removing lead paint from masonry