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Presentation at the Annual APT meeting in Victoria Canada, 2011.
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B Y M A RY F. S T R I E G E L , E R I C G U I D RY, M O L LY M C G AT H , A N D C AT H E R I N E A R C E N E A U X
N AT I O N A L C E N T E R F O R P R E S E RVAT I O N T E C H N O L O G Y A N D T R A I N I N G
A comparison of cleaning methods for graffiti removal from masonry
materials
What are important factors to consider before removing graffiti?
Graffiti or Art?
The Polish city of Lodz is making huge waves in the street art world. Under the patronage of Mayor Hanna Zdanowska … In MyModern Met website 9/29/2011
Gentlest Means Possible: Do no harm
Type of graffiti materials
MarkersSpray paintsOthers
Weathering factors
Sunlight = UV cross-linking or fading
TemperatureHumidity
“Graffiti peeling – yellow” by Greig Christie, August 12, 2005. Flickr. Accessed 10/09/2011.
How do we evaluate graffiti removal methods? NCPTT study
What are people using to remove graffiti?
Survey of Professionals: requests to conservators and preservation professionals in the field
20 responses received Most used chemical cleaners Organic Solvents: Acetone, MEK, Xylene Solvent poultices Solvent Gels Commercial Products
Solvent based Hydroxide based Peel Away products
Selection of masonry types
MarbleRed, Low Fired BrickBeige, Modern Brick
Selection of Graffiti materials
Type: Rust-oleum EnamelColor: Red, Black
Choice of cleaning systems
Peel Away 1®Wipe Out Porous Surface Graffiti Remover®Sure Klean® Fast Acting StripperLaser Cleaning
Peel Away 1®
A poultice like paste containing caustic cleaners
Active Ingredients Calcium Hydroxide Magnesium Hydroxide Sodium Hydroxide
pH = 13Requires a separate
neutralizing solution
Wipe Out Porous Surface Graffiti Remover®
Basic gelActive Ingredients
75% proprietary ingredient
1-5% Monoethanolamine
1-10 % Potassium Hydroxide
1-5% Nonylphenol Ethoxylate
pH = 11-12
Sure Klean® Fast Acting Stripper
Solvent-based gelActive Ingredients:
Dichloromethane Amine Methyl Alcohol Xylene Alcohol
pH = NAMajor handling and
environmental issues
Laser Cleaning
Remove material from a solid surface in a controlled fashion
Active Ingredients = NA
pH = NAExpensive equipmentTime intensive
. .Cutting and coring samples. .
Sample Preparation
. . .Painting samples with red
and black stars. . .
. . .Artificial weather exposure chamber. . .
. . .Colorimetry. . .
Testing Methods
Laser profilometry
Visual appearance ranking
Results: Color change
H-B Red H-B Black L-B Black M Red M Black0.000
0.100
0.200
0.300
0.400
0.500
0.600
Percent Change in L Value
Peel AwayLaserStripperWipeout
Laser Profilometry: Texture change
Improvement of Visual Appearance
0
10
20
30
40
50
60
70
80
90
100
Poultice
Laser
Stripper
Gel
H-F Brick Red H-F Brick Black L-F Brick Red L-F Brick Black Marble Red Marble Black
Percent Ranked #1 in Visual Appearance Survey
What have we learned?
Of the products tested:Peel Away was most efficient for removing paint and the
least physical damage to the surface, but it was difficult to remove from some surfaces
Sure Klean Fast Acting Stripper was a gel that limited penetration into the material. It was a poor performer overall.
Wipe Out was difficult to control during application and caused the relocation of pigment. It performed well on the high fired yellow brick.
Laser ablation required a great deal of pre-experimental examination to be effective.
Where do we go from here?
Limited study established methods for evaluating graffiti removers
A greater range of products must be tested, with an emphasis on cleaners that are: Environmentally friendly Effective at removing a range of materials Safe for the cultural resource, the environment, and the user
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