Guide to Mold Removal by Media Blasting

Post-Cleanup using a baking soda spray process

Test report on the effectiveness of baking soda media blasting for removing mold contamination
- Media Blasting Procedure to Remove Mold
- Mold Lab Testing Results Before & After Media Blasting
Questions & Answers about mold removal using media blasting: how to remove mold contamination from irregular or hard-to-access surfaces
References

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Guide to media blasting for cleaning mold-contaminated surfaces: this document reprints our article on use of baking soda media blasting for surface cleaning in the removal of mold and fungal growth from building surfaces. This material is reprinted from "Testing the effectiveness of baking soda media blasting for cleaning fungal contamination in buildings," Daniel J Friedman, Dennis Melandro, Indoor Environment Connections, Rockville MD, June 2003.

The media can be baking soda (discussed here) or dry-ice particles. Both are equally effective. The dry-ice or frozen CO2 method has the advantage of producing less media particulates which add to the volume of dust and debris needing to be vacuumed and removed after blasting--DJF].

Report on Tests of the effectiveness of baking soda media blasting for cleaning and removal of fungal contamination in buildings

Dennis Melandro, First Alert Emergency Services, Rockville Centre, NY,
Daniel Friedman, American Home Service, Poughkeepsie, NY.

Media Blasting Decision and Procedure for Mold Remediation

Media blasting is particularly useful for thorough cleaning of irregular building surfaces such as the under-side of a roof deck or other attic or building surfaces where nails protrude, or where cross bracing or bridging obstruct building surfaces and prevent easy cleaning by simple scrubbing.

Media blasting is also suitable for thorough cleaning in difficult-to-access areas such as tight crawl spaces and attics where mold growth needs to be removed.

[OPINION: Media blasting is a very effective way to clean irregular or hard-to-access moldy surfaces in buildings, and it avoids the moisture surge and possible moisture damage to other building areas that can occur when wet methods such as power washing are used indoors.]

In the first half of this article, Dennis Melandro, a mold remediation contractor reports on field experience regarding baking soda media blasting for surface cleaning during mold remediation.

In the second half of the article Daniel Friedman, a building diagnostician and forensic microscopist reports on laboratory test results for samples collected to evaluate the effectiveness of Mr. Melandro's cleaning effort.

This mold remediation example photograph (by DJF) shows an oriented strand board (OSB) subfloor after cleaning using a blasting method and sealing using Fosters 4051™ clear coating. The remaining photographs in this article were taken at the study site or in the laboratory described in this report.

While we have performed the baking soda media blasting technique many times to clean irregular building surfaces, here we report on a specific test case for which we collected a variety of samples selected to test the effectiveness of the cleaning process at several points.

Remediation of large areas of fungal contamination in residential and commercial buildings is usually performed by a company with experience in construction demolition and cleaning, airborne particle contaminant control and use of special equipment to protect both workers and building occupants from contaminated or irritating dust and organic debris.

When large areas are contaminated, mold remediation should follow a protocol specified by an independent third party who has expertise in defining the scope of work and experience in recognizing, sampling, and identifying problematic mold in buildings. These experts are drawn from several professions including industrial hygiene, mycology, aerobiology, and building science.

Dennis Melandro, received a protocol for a single-family, two-story home with full, unfinished basement. The house was wood-frame construction. It was an unoccupied rental property in which a basement pipe break and leak had gone undiscovered for approximately three weeks.

By the time Melandro was contacted, the basement had heavy visible mold growth on the two- by eight-inch joists, sub-flooring of the floor above, and on the triple two- by 10-inch main headers. Insulation and the building contents were assumed to be contaminated as well. The first floor consists of four rooms, all of which had mold on plaster walls, and ceilings. The second floor has two bedrooms where mold was visible on the walls.

The client's insurance company's protocol specified removal of all basement ceiling joists, supporting girders, and first floor subfloor, along with the building contents. In other words they specified that the entire first floor structure be removed. There was no mention of how the house was to be supported during this step. All wall and ceiling coverings were also to be removed.

In Melandro's view, the call for complete framing removal was drastic and unnecessarily costly, particularly as in this instance there was no report that the building structure had been damaged by fungal contamination.

As an alternative approach, I proposed removal of mold contamination from the framing surfaces using the Armex Accustrip™ system. This method entails a high-pressure compressed-air spray (consisting of a hopper holding the baking soda and a handheld gun for precision) using a baking soda abrasive.

We've found that this method cleans irregular and problem surfaces such as subfloor with protruding nails and the multiple building framing cavities which would otherwise be both labor intensive and difficult to clean by manual scrubbing and vacuuming. I proposed that the Armex™ process be used to remove mold spores from the ceiling joists and main triple headers (as well as other surfaces).

The spray blasting was to be followed by HEPA vacuuming to remove any media or debris residue, followed by vacuuming with a bio-wash. The client accepted my proposal. The problem area before and after our blasting treatment is shown in Photos 1 and 2 above.

In order to contain the mold, debris and baking soda residue while using the Armex Accustrip™ system, we kept the first-floor sub-floor in place until the media blasting was completed. Then, we removed the first-floor sub-floor and we hand sanded the now-exposed top side of the joists, followed by HEPA vacuuming and damp wiping.

In other scenario's where there are windows, doors and opening we would set up critical barriers to contain the residue from the media blasting, while an air scrubber is filtering the air borne mold spores, baking soda and residue from the surface of which this method is being applied. During this procedure, all personnel were equipped with protective clothing and respirators.

When the mold remediation was complete, samples of the remediated surfaces were examined. To evaluate the effectiveness of our cleaning effort, we called on Daniel Friedman, an independent aerobiologist with expertise in both building inspection and fungal spore identification.

Mold Removal by Media Blasting of the Moldy Surface: A test of effectiveness - Mold Lab Testing Results

In the aerobiology lab Daniel Friedman examined the tape samples of surface particles and debris from the remediation project. Samples were studied using a very high powered light forensic microscope (up to 1920x polarized light microscopy and simple micro chemical methods) and appropriate slide preparation methods. Melandro and Friedman had agreed on the time, type and location of surface samples to be collected during the project.

Friedman's own research as well as that of others in the field indicate that surface sampling combined with visual inspection is both more reliable and more important than stand-alone air sampling or culturing methods for characterizing building contamination.

Chaetomium globosum, Chaetomium aureum and Stachybotrys chartarum are dark "black molds" frequently found in buildings that have been subjected to flooding. Their medical risk has been somewhat overblown by the excited news media, but they are indeed telltale organisms very often pointing to a presence of more serious fungal contaminants such as Penicillium sp. and Aspergillus sp. in the same buildings.

These latter molds are lighter in color and often grow hidden within building cavities. Unless they are quite heavy, colonies of these genera are often missed by a casual inspection which finds and reports "toxic black mold."

Because we wanted to understand the effects of blasting and to evaluate the possibility of recontamination of the 'cleaned' surface by fungal debris that might be transported by airborne blast-media, we decided to examine samples of surface conditions at several steps in the cleaning process:

Surface Mold Contamination Screening Tests performed after media blasting with baking soda and before HEPA vacuuming

Photograph of cellulose fragments on the test surface after media blasting with baking soda, before vacuuming

Photograph of Chaetomium mold spore on the test surface after media blasting with baking soda, before vacuuming

After media blasting with baking soda and before HEPA vacuuming, the sample area included contamination, which I speculate settled as airborne debris.

In these mold test samples, Mr. Friedman found fiberglass fragments, debris, cellulose fragments more frequent than in after-HEPA vacuuming sample below, and he found both individual fungal spores spore clusters including basidiospores, Periconia sp., and unidentified fungal conidia and hyphal fragments which appeared to be Chaetomium globosum particles, perhaps fractured by the blasting process.

See the photos here which show cellulose fragments and Chaetomium globosum. On other studies, Daniel Friedman has also found fairly uniform surface contamination by fungal debris, mostly hyphal fragments, when an inexperienced contractor used contaminated wipes and a contaminated vacuum attachment across many surfaces.

Surface Mold Contamination Screening Tests After HEPA vacuuming and wiping

Photograph of a mold test sample from a previously moldy surface after cleaning
by baking soda media blasting

After HEPA vacuuming and wiping, the sample was clean of fungal spores.

It contained incidental occurrences of media particles less than one micron in size, cellulose particles that Friedman speculates were removed from the blasted wood surfaces, and skin cells.

There were no fungal spores found in the sample, as shown in the photograph.

Media Blasting Test Results, Comments by Daniel Friedman

These results suggest that the media blasting approach is effective in cleaning exposed wood surfaces of fungal contamination, but that special care needs to be taken to avoid recontamination by airborne, contaminated dust, vacuum attachments, or surface wipes. Contractors need to look carefully at dust control, vacuuming and wiping methods to take full advantage of the cleaning provided by surface blasting.

While more research would be useful to refine the procedure and confirm its long-term efficacy, even with these incomplete pre and post-blasting tests there was good evidence that there was no substantial post-blasting and cleaning surface contamination.

Media Blasting Test Results, Comments by Dennis Melandro

First Alert Emergency Services has completed numerous mold remediation projects. We have saved structures and have received successful final clearance test results leaving both residential and commercial building owners very pleased with our completed projects.

The media blasting process is more cost effective and less time consuming than extensive demolition. Most importantly, the final result is a cleanup which has successfully removed the problem mold in order to provide a mold-safe indoor environment.

We've had great success using the media blasting method for mold, and we've also used it for the removal of soot from roof rafters, ceiling joists, sub-flooring and wall framing. As it is less abrasive and thus less destructive to brick than sand blasting, it and can be used on masonry exteriors as well.

By contrast with common remediation methods which hand clean and seal the framing and sub-floor, leaving everything white or shiny with paint, the media-blasting process leaves a fresh, clear wood surface at which you would never know that there was a previous fire or mold problem. The contamination has been removed.

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Technical Reviewers & References

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About the Authors

Dennis Melandro is an ASCR certified restorer, MEHRC mold supervisor, IAQA certified mold remediator and an expert in mechanical hygiene for HVAC systems. He founded First Alert Emergency Services and has been servicing the insurance industry for fire, water, smoke and mold remediation for the past 14 years. He can be reached by e-mail to info@firstalertemergency.com or by phone at (800) 924-1119.

Daniel Friedman is an aerobiologist specializing in fungal spore identification. He has worked as a building failures investigator since 1978 and has specialized in indoor mold contamination and fungal spore identification since 1986. His laboratory is in Poughkeepsie, N.Y. His background and credentials are at InspectAPedia.com/danbio.htm. He can be reached via his online contact information. In-depth building diagnosis and repair research and advice can be read at Mr. Friedman's website InspectAPedia.com. Reprinted with permission from the JUNE 2003 edition of Indoor Environment Connections newspaper. Daniel Friedman - principal author/editor of the InspectAPedia^® Website.

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The Use of Ozone Generators Indoors for Control of Odors and Mold Removal in buildings: A Summary of Hazards and False Claims
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
Environmental Health & Investigation Bibliography - our technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
Adkins and Adkins Dictionary of Roman Religion discusses Robigus, the Roman god of crop protection and the legendary progenitor of wheat rust fungus.
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention Program for Certain Vegetable Crops," David B. Langston, Jr., Extension Plant Pathologist - Vegetables, University of Georgia (PDF document) original source: www.reeis.usda.gov/web/crisprojectpages/209797.html
"Disease Prevention in Home Vegetable Gardens," Patricia Donald, Department of Plant Microbiology and Pathology, Lewis Jett
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
"Management of Powdery Mildew, Leveillula taurica, in Greenhouse Peppers," Ministry of Agriculture and Lands, British Columbia - Original source: www.agf.gov.bc.ca/cropprot/peppermildew.htm
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
Fungi, Identifying Filamentous, A Clinical Laboratory Handbook, Guy St-
US EPA: Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
Mycology, Fundamentals of Diagnostic, Fran Fisher, Norma B. Cook, W.B. Saunders Co. 1998, ISBN 0-7216-5006-6 (buy this book at Amazon)
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