Media Blasting Myths
August 1, 2006
A few short years ago a small revolution occurred. Media blasting for architectural restoration - baking soda, dry ice, and other blast media - became a mainstream tool for mold remediation, fire restoration, and other large cleaning and reconstruction jobs. It seems that this revolution is in full swing today. The leading technologies, dry ice blasting and baking soda blasting, are still growing in effectiveness, use and acceptance.
This doesn't mean, however, that these two allies in the revolution always agree. In fact, one of the raging debates involves the question of which process is "right."
As the leading manufacturer/distributor of both processes, I hear the debate every working day. While I understand the arguments from both sides, I do have to say that there is a great deal of misinformation, or misunderstanding, about both of these technologies. In an effort to clear the air, I will attempt to expose some of the more popular "myths" I must debunk almost every day.
Myth No. 1 - All Media Blasting Gives the Same ResultsAssuming that dry ice and baking soda blasting are equal in their results is probably the most misunderstood, and overlooked, area contractors consider when evaluating the two. I even fall prey to this on occasion. For instance, when asked to compare and contrast the processes, many times, for argument's sake, I will allow that the results are equal. Then I forget to remind the listener that they are not the same. Typically soda and ice give similar results in light blasting applications, e.g. mold remediation on wood. The difference in results come when you get into harder applications, such as smoke and fire damage (Image 1 and 2), or paint stripping (burnt paint on cinder block or concrete.) Baking soda is mild when necessary, aggressive when required and, without a doubt, more effective, up to five times faster, and cheaper to use in these applications.
When comparing all blasting processes, only baking soda media has the ability to deodorize by neutralizing the alkalinity of soot and fire damage. Further, damage to wood, and other soft substrates is far less with baking soda than similar blasting with dry ice pellets (Image 3 and 4).
Myth No. 2 - There's Nothing to Clean up with Dry-Ice BlastingThis statement is incorrect. I have heard the term "secondary waste" used recently. This refers to the spent media: in the case of dry ice, gaseous carbon dioxide. I guess that means that we can refer to the stuff were blasting off the surface (mold, soot, wood fibers, insulation, etc.) as the "primary waste." Remember, when you're done media blasting you should still clean every surface with a vacuum, or damp-wiping, or both, irrespective of what's on the surface or if it's "primary" or "secondary" in nature.
Keep in mind also that the "secondary waste" of dry-ice blasting is a large quantity of invisible, odorless gas. In normal concentrations, we take it in with every breath. In heavy concentrations, however, CO2 poses a very real danger of asphyxiation. While this can be overcome with the use of proper ventilation equipment and procedures and gas level monitors, the possibility of an oxygen deprivation injury still exists.
Myth No. 3 - Baking Soda Blasting Will Envelope Me in a "Cloud of Dust" and Limit My Ability to be ProductiveJust like any process, correct procedures need to be followed to get the right results. For good blasting visibility, three areas need to be addressed when setting up a soda-blasting job; media flow control, proper lighting, and proper ventilation. Get all three correct, and productivity will be maximized.
Media flow control means, simply, choosing a soda blaster that can effectively meter small quantities (1 to 1.5 pounds per minute) into the blast stream. In the right system this is all that is required to be very productive, while eliminating unnecessary dust in air and waste on the ground. Proper lighting, simply put, means a bright, portable light in the area of the blast nozzle. Many blasting jobs occur in crawlspaces and attics with very poor lighting. If the operator has good lighting, the blasting is much quicker because the "before" and "after" are easier to discern. Lastly, proper ventilation requires "turning over" the air in the blast area. While several techniques are commonly used, fans ducted to an external, reusable dust sock typically provide adequate, air-clearing ventilation (Image 5).
Myth No. 4 - Baking Soda is Too "Messy" to be Contained in One AreaIt is definitely true that media blasting, of all types, can be hard to contain. The forces of compressed air and blast media are strong. Actually, the "myth" is that dry ice doesn't suffer from this problem. If you breach containment on a mold job while blasting with soda, you will likely have dust and other contaminants (mold spores) in the breached area. Similarly, if you breach containment while ice blasting, you will still have contaminants, just no accompanying telltale dust. Most contractors using media blasting learn the tricks to better containment quickly, and proper training at start-up can shorten the learning curve even more.
Myth No. 5 - Media Blasting Machines Require a Certain-Size CompressorThis is almost totally based on a simple misunderstanding that comes up most often when a contractor is ready to buy a system and wants some way to compare one system to another. This tends to be a poor indicator of system performance or effectiveness, mainly because, as common sense might dictate, large nozzles require more air than small nozzles. Therefore, if a system comes with a large nozzle, it will use large quantities of air and probably cover a large area when blasting.
To be productive, a blast system will likely require large quantities of compressed air. Think of it like this: would you rather sweep a warehouse with a push broom or a whiskbroom? Embrace the fact that you're using a large compressor; small ones don't get nearly the same amount of work done.
Myth No. 6 - All Blasters Are Equal; Price and Color Are the Only DifferenceBaking soda and dry ice are blast media that have specific problems associated with their use. Heat, humidity, and compressed air laden with water and contaminants all have a negative impact on the way these exotic media behave.
Baking soda tends to get lumpy when wet, and small quantities (1.5 pounds per minute and less) are hard to meter into the blast stream consistently. Dry ice begins deteriorating rapidly from the time it is made, becoming less aggressive and harder to flow through the machinery, and both the dry ice and the equipment tend to freeze up when you have a little water in the mix.
Choose a machine based on its ability to consistently flow, or feed, the medium into the blast stream and out the nozzle at the rate the job requires. There is no hard rule of thumb here, but you usually get what you pay for. Cheap blasters, whether for ice or soda, are generally inferior to more costly ones. Quiz your supplier and find out whether his or her system is capable, and make wise choices based on their ability to answer that question. When in doubt, request a demonstration or several references.
Myth No. 7 - Be it Soda or Ice, Blast Media is All the SameWrong. Of course, baking soda is sodium bicarbonate. Baking soda, however, can be treated with flow agents and moisture-repellent materials to enhance its "flowability" and resistance to moisture. These additives are either hydrophilic (for most applications) or hydrophobic (for extreme moisture conditions.) All soda-blast systems run more consistently and with less maintenance when using baking soda with these flow agents added.
Dry ice is 100% solid carbon dioxide. This material is usually made to order and shipped to the end user. Manufacturing techniques, humidity levels, packaging, and other factors can alter the initial quality of the ice. Since dry ice is perishable, with a lifespan of less than a week, distance from the manufacturer and delivery schedules may be a factor in ice quality when blasting.
Myth No. 8 - Training and Start-Up Assistance in the Field is Not RequiredI've heard it before: "my guys are mechanically inclined, they don't really need the training." Mechanically inclined or not, most technicians are unfamiliar with blasting systems. Those that are familiar with blasting are generally knowledgeable about traditional media blasting. Both dry ice and baking soda applications are distant cousins to more traditional methods. From a safety and performance standpoint, competent startup training and assistance is a requirement. Demand this from your supplier.
Myth No. 9 - Field Support Doesn't ExistSooner or later, you will have a problem with whatever system you use for blasting. Chances are you'll pick up the phone and call the distributor or manufacturer of the blast equipment you own. What do you expect to get? An optimist would expect prompt, competent answers that will get the situation resolved. A pessimist would expect a voice mail, bad advice, and help worth less than the cell-phone minutes required to make the call.
Get references from your supplier (before purchasing) and ask tough questions. Find out ahead of time whether you should be optimistic or pessimistic about support for your equipment in the future.