Media Blasting and Mold Remediation
April 9, 2008
Conduct a quick Google News search for “mold,” and see what you find. Mold continues to make headlines, appearing everywhere from homes and apartment buildings to courthouses and medical facilities. Mold problems can be brought on by flooding, roof or plumbing leaks, damp basement and crawl spaces, or anyplace moist air is left to condense on cold surfaces. Mold will most likely be found where there is water damage, a high relative humidity or dampness.
Mold in small amounts should not cause much alarm; however, mold should never be allowed to multiply. When it is found in large amounts, mold can cause health problems, odors and damage to building and home materials, and even structural damage in wood.
Conventional Mold RemediationThe primary step in removing a mold problem is to correct the moisture problem. If the mold is removed but the moisture problem is not controlled, it will return. Once the source has been addressed, the next step is completely cleaning and removing any existing mold.
There are a number of methods contractors are using in mold remediation, and while many of these methods are effective, some have the potential to also cause it to spread into other areas. Wet vacuums, for example, are used when the material being vacuumed is still wet. If the material is not wet, the vacuums may actually aid in spreading the spores.
Conventional cleaning methods require mold remediators to manually sand, scrape or wire brush the mold from the contaminated surface. This can be a slow, tedious and generally unpleasant process to endure. It is also virtually impossible to completely remove the mold through these methods; contractors are often limited by tight angles and close and confined spaces, which can lead to difficulties when trying to sand mold off of wood.
Other methods include the use of biocides, which can help kill germs and prevent health risks associated with the mold after the cleaning has taken place. However, they do not replace the need for a detailed cleaning. The allergic reactions experienced from mold are due to metabolites found in the mold spores, which seep into the material the mold is growing on. Biocides kill the spores, but do not always fully remove the metabolites, leaving the allergen source in place. Dead mold is still allergenic. The only ways to eliminate the metabolites is to completely clean, or remove, the moldy material.
Media BlastingOne of the most popular techniques for mold remediation is media blasting, primarily because the blasting systems provide a very thorough cleaning without the need for intense manual labor.
There are a number of different media blasting methods on the market being used by contractors, from water and corncobs to dry ice, steel grit and walnut shells. Water blasting is typically ineffective if the mold particles are adhered to the surface.
Sand and grit blasting (steel, silicon, walnut, etc.) are considered aggressive cleaning methods and are used more frequently for rusted surfaces; graffiti removal; coatings; surface preparation or floor cleaning. While sand and grit blasting disturb the spores, the mold is often broken up into smaller particles, which can pass through a HEPA filtration system and contaminate other areas. Sandblasting is generally messy and creates fugitive dust, which is usually toxic and potentially damaging to moving parts in the area.
Plastic chip and sponges with abrasives blasting are often designed to be recyclable, enhancing cost effectiveness. According to the “IICRC S520 Standard and Reference Guide for Mold Remediation,” the recycling of blast media for mold removal is not advised, therefore plastic and sponge blasting should only be used once when cleaning mold.
Soda blasting is a very effective and popular method of media blasting for mold remediation, particularly because it does not cause much damage to wood. Soda blasting is softer than the other blasting media; however, it produces a significant amount of dust and leaves a good deal of debris from the blast media that has to be cleaned.
With regard to mold remediation, dry ice blasting works somewhat like sandblasting or high-pressure water blasting, but without causing significant structural damage to the wood surface. Instead of using hard, abrasive media to grind on the affected wood, dry ice is accelerated to supersonic speeds, creating mini-explosions on the surface to lift the mold off the wood.
Dry ice blasting will typically remove about 1/32 of the wood surface being cleaned, using kinetic energy and a scrubbing action to clean. This blasting application is enough to effectively remove the mold spores, but not enough to alter the structural integrity of the wood in the contaminated area. The carbon dioxide gas sublimates into the atmosphere after it impacts the surface being cleaned, leaving no additional waste streams. The residual mold and wood removed by the blasting process is then removed through vacuuming.
When considering which media blasting methods to use, it is important to look at the impact that the media will have on what is being cleaned, as well as the environment. Mold remediators can get in between beams and into roof sheathing, allowing for complete mold spore removal and eliminating the need for encapsulation and sometimes biocides.
While there will always be some levels of mold in the air, certain media blasting methods can provide a safe and efficient way to obtain a thorough and complete spore removal on wood surfaces affected by mold.