2 evaluation of cleaners for government issued headstones

Evaluation of Cleaners for Government Issued Headstones

Mary F. Striegel and Jason ChurchNational Park Service

National Center for Preservation Technology and Training

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NCA Maintains 3 million+ gravesites.

• Today’s marker is tomorrow’s historic headstone.

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NCA preserves historic headstones which are 50 years or older.

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NCPTT is a leader in advancing preservation technology.

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NCPTT was contracted by NCA to evaluate cleaners for marble headstones based on soiling and biogrowth.

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Recommendations must meet NCA National Shrine Standards.

• Headstones, markers, niche covers are clean, free of debris and objectionable accumulations.

• Headstones, markers, niche covers are not damaged by cemetery operations.

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Definitions

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The StudyPhase I (2004-2005)

• Define Goals

• Choose Cleaning Criteria

• Evaluate commercially available cleaners based on:

– Appearance

– Biological Re-growth

– Physical and Chemical Changes

– Ease of Use

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Selection of Cleaners:

Table 1. Chosen Cleaners are ordered from Acidic to Basic.

Cleaner H2Orange2 Grout Safe Kodak Photo-Flo D-2 Marble Cleaner Daybreak

pH 3.81 7 9.5 10.5 12.1

pH Acidic Basic Alcohol Chelate Solvent Surfactant Bactericide

D-2 9.5 X X

Daybreak 12.1 X

H2Orange2 Grout

Safe 3.81 X

Kodak Photo-Flo 7 X X X

Marble Cleaner 10.5 X X X X

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Bath National Cemetery

• Bath, NY

San Francisco National Cemetery

• San Francisco, CA

Santa Fe National Cemetery

• Santa Fe, NMAlexandria National Cemetery

• Pineville, LA

Jefferson Barracks

National Cemetery

• St. Louis, MO

Field Test Sites

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Implement Field Studies5 cleaners + water

1,440 test patches

240 stones

5 National Cemeteries

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Micro-organisms• Bacteria: can

slowly cause stone loss

• Fungi: Can change visual appearance

• Algaes: provides the most visual changes

Fungi sample found on marker in San Francisco.

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Phase II (2005-2007)

• Monitor regrowthin the field for 18 months

• Evaluate cleaning effects on test stone in the lab

• Elimination: H2Orange Cleaner and Kodak PhotoFlo

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Elimination: Bath National Cemetery

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Phase III (2008-2011)

• Long-term monitoring at two sites

• Pineville and Jefferson Barracks cleaned study headstones

• Alternate laboratory study was devised at Harvard University

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Results

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Significant Findings from the Study

• Field studies showed:

– Kodak Photo-Flo was the first cleaner to fail in the field (greatest biological regrowth)

– H2Orange Safe Cleaner failed after six months at Jefferson Barracks National Cemetery (killed bacteria but left green fungi)

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Significant Findings from the Study

• Lab studies showed:– Daybreak cleaner left

significant salt deposits on stone

– D2 Biological solution left small amounts of salts on stone (pH buffer additive?)

– D2 Biological Solution was reformulated, no salts found on repeat testing with new formula

Daybreak

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Significant Findings from the Study

• Further biological studies showed:

– WEG Marble and Granite Cleaner failed after 188 days in laboratory accelerated studies.

– D2 Biological Solution performed as well as Daybreak without harmful salt residues.

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ClimaticDifferences

Semi Arid Steppe: Santa Fe

Humid Subtropical: Alexandria

Mediterranean: San Francisco

Humid Continental: Bath Jefferson Barracks

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Location Differences• Sunny areas:

Biocidal effects last much longer.

• Shady areas:

Fungal growth is more likely to return.

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Issues to Consider

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Headstone Soiling

• Dirt

• Air Pollution

• Biological Organisms

• Bird Droppings

• Plant or Tree Sap

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Other Threats to Headstones

• Salt Damage

• Freeze Thaw Cycles

• Improper Cleaning

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Preservation Practices

• Use the gentlest least invasive method

• Consider long-term effects

• Minimize cleaning impacts

• Don’t remove original surface

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Cleaning known to damage stone

• Bleach and Bleach like products

• Strong acids or bases

• Power tools

• Pressure washing

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Cleaner Factors to Consider

• Manufacturer’s Recommendations

• Dilution ratio

• Dwell time

• Biocidal Cleaners

• Lightening with time

• Temporary non-permanent color changes during cleaning

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Recommended Actions

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Cleaning Recommendations

• Use D2 Biological Solution or similar biocidalcleaner, following manufacturer’s directions. Do not dilute.

• Apply to WET stone surface using a sprayer.

• Gently agitate with a soft bristle brush.

• RINSE thoroughly with water.

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Cleaning Frequency Factors

• Research offers observations, but frequency of cleaning will depend on location and climate of individual cemeteries.

• Different locations will need different cleaning schedules.

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Spot Cleaning

• Minimize the frequency of cleaning the entire cemetery by scheduling spot cleaning on those headstones located in shady areas that exhibit more biological growth and soiling.

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Summary

• Of the five cleaners tested, D2 Biological solution was most effective and left no harmful residues.

• Daybreak is a bleach solution.– Continued use of Daybreak will result in long term

damage to headstones.

• Use of high pressure power washers can erode the headstone surface and deteriorate headstone.

• Use of chemical cleaners can be successfully accomplished by a three-person team.

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