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Basic Information

This program is nearly completed and encompasses many research efforts to find less costly and more effective ways to remove lead paint from interior and exterior painted surfaces. The first of three projects were completed in cooperation with the City of Buffalo, New York, and the Army Corps of Engineers Construction Engineering Laboratory (CERL). The second study was a continuation of the Buffalo study, and the abatement technologies with promising results were further demonstrated on exterior wood and brick surfaces in Kentucky and Illinois. This study was also conducted in cooperation with the Army Corps of Engineers. The last lead-based paint abatement project was conducted in an unoccupied residential home in Butte, Montana in cooperation with the Silver Bow County Health Department.

The three most recent research projects Lead-based paint abatement team are discussed in detail below in chronological or der.

Turbo Wet Abrasive Blasting

Figure 1. Buffalo, New York - Torbo Wet Abrasive Blasting.

Buffalo, New York Site (Figure 1) Three technologies were evaluated for their lead-based paint removal efficiency and cost effectiveness. This research project was conducted during the spring/summer of 1996 at several unoccupied residential homes in the city of Buffalo, NY:

  1. Pelletized/Granulated CO2 blasting (demonstrated on interior surfaces) - This technology uses shaved block dry ice, which was also replenished approximately every 15 minutes to create a fine crystalline blasting medium. The removal mechanism for both technologies is a three-part process where there is a mechanical abrasion of the surface with the pellets/granules; a spalling of the material surface caused by rapid expansion of the carbon dioxide during sublimation; and thermal fracturing between the substrate and the surface causing the material to expand and contract. This process causes the lead paint to fracture into chips as it leaves the surface.
  2. Chemical stripper-interior surfaces (architectural trim: baseboards, door frames) - The stripper is a two-part system comprised of potassium hydroxide (13.2% by wt in water) and a proprietary polymer (9% by wt in water). The chemical is spray-applied to the surface. After a specified dwell time (depending on the thickness of the paint, ambient temperature, etc.), the paint remover is scraped from the surface with a putty knife.
  3. Torbo wet abrasive blasting system (demonstrated on exterior surfaces) - The system combines an abrasive media and water to create a slurry mixture (80% abrasive to 20% water) that is fed to a blast nozzle much like a conventional blasting system. In theory, each particle of the abrasive is encased in a thin layer of water. It utilizes this coating to both reduce the heat generated by friction and form a cohesive bond for the dust created by the blasting process that reduces the fugitive particulate emissions.
Torbo Wet abrasive Blasting System

Figure 2.Ravena, Kentucky -- Pre-Tox 2000 using Torbo Wet abrasive Blasting System

Kentucky/Illinois Site (Figure 2 & 3)- Three abatement technologies were evaluated on exterior wood surfaces in Ravena, KY and brick surfaces in Elgin, IL during the spring/summer 1997:

  1. Torbo wet abrasive blasting system - The technology was demonstrated on both exterior wood and brick surfaces because it showed promising results at the Buffalo, NY site.
  2. Blastox - It is a di- and tri-calcium silicate-based abrasive additive material similar in chemical composition to Type I cement. It is typically added at a 20-25% ratio by weight to a non-recyclable blasting media such as mineral sand or coal slag. Blastox is applied to lead-based painted surfaces via the Torbo blasting system.
  3. Pre-Tox 2000 - It is a cementitious paint-like mixture designed to be applied to lead-based paint surfaces and allowed to cure and adhere to the paint coating. It is then removed in conjunction with the underlying lead-based paint coating using the Torbo blasting system.
Blastox using Torbo Wet Abrasive Blasting System

Figure 3. Elgin, Illinois--Blastox using Torbo Wet Abrasive Blasting System


Table 1. Lead (Pb) Concentrations on Wood and Brick Measured by XRF Lead Concentration (mg/cm2)
Technology
Combination		 Substrate N Mean Std. Dev. Minimum Maximum
Before Removal
Torbo w/ Blastox Wood / Brick 15 / 15 36.9 / 5.59 9.52 / 1.78 15.5 / 1.5 51.9 / 9.7
Torbo w/ PreTox Wood / Brick 15 / 15 29.7 / 8.18 9.66 / 3.71 13.1 / 3.9 41.4 / 15.2
After Removal
Torbo w/ Blastox Wood / Brick 75 / 75 0.24 / 0.14 0.22 / 0.09 0 / 0 1.1 / 0.4
Torbo w/ PreTox Wood / Brick 75 / 75 0.16 / 0.11 0.16 / 0.14 0 / 0 0.7 / 1.1
N = number of XRF readings taken on wood and brick surfaces

Butte, MT Site (Figure 4) - Two abatement technologies were evaluated on interior wood surfaces in a temporarily unoccupied residential home in Butte, Mt in January 1999:

Spray application of PR-40/LeadX

Figure 4. Butte, Montana - Pr-40/LeadX, a chemical stripper abatement technology.

1. PR-40/LEADX - It is a liquid-chemical paint remover containing a lead immobilizer and a paint remover. The removal system containing LEADX, immobilizes lead molecules in lead-based paints through a process by which the LEADX bonds to the lead molecule and transforms the lead into a nonleachable form.

2. Cryokinetics (pelletized carbon dioxide blasting) - This technology is very similar in principle to the carbon dioxide blasting technologies demonstrated at the Buffalo, NY site.

Conclusions/Recommendations

Based on the results of the research projects, demonstration budgets should allow for the disposal of residual paint sludge as RCRA hazardous wastes, unless proven otherwise by TCLP analytical data. Indoor air samples should be collected before abatement for comparison with data taken during and after each technology demonstration. This information should be used to determine the potential exposure levels to lead particulate by abatement personnel as well as occupants of the affected buildings.

Encapsulate Paint Remover Systems:
This technology type effectively removed Lead-based paint (LBP) from interior wood components. The surfaces were rendered lead hazard-free and suitable for repainting. The maximum personal exposures to airborne lead were less than 10% of the OSHA Permissible Exposure Limit (PEL).

Carbon Dioxide Blasting Systems:
Granulated and pelletized CO2 blasting were not effective in removing LBP from interior wood surfaces without rendering the surfaces non-suitable for repainting. The airborne lead particulate exposures generated during granulated carbon dioxide blasting technologies exceeded the Permissible Exposure Limit (50ug/m3) as well as the OSHA Action Level by a factor of 12.

Stabilization Technology Systems:
Both stabilization technologies, when applied in combination with wet abrasive blasting, were capable of removing the lead-based paint from both exterior wood and brick masonry with minimal or no damage to the underlying substrates. The wood surfaces will require only light sanding and the brick surface will need a small amount of mortar joint tuck pointing prior to repainting them, etc. Both technology combinations were effective in removing lead-based paint from wood and brick as clearly evident by the residual lead levels of the resulting surfaces measuring significantly below the HUD Guideline of 1 mg/cm2 at both the wood and brick study sites (Table 1).

Contact:

Lead Paint Research
Alva Daniels
Phone: (513) 569-7693
FAX: (513) 569-7471
E-Mail: daniels.alva@epa.gov

Office of Research & Development | National Risk Management Research Laboratory

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