Published 5/1/2010

The Bicarbonate Soda Blast Solution

Understanding the technology is important for yielding effective results.

It’s often thought of as sand blasting with baking soda.

Former Editor-in-Chief, Production Machining

It’s time to consider soda blasting for surface cleaning and coatings removal.

Clemco’s soda blast cabinet features the ClearView targeted, high-velocity ventilation system that helps keep the dust level down to make the process effective.

To address a variety of applications, Natrium offers three different grades of sodium bicarbonate crystals that measure 150, 300 and 340 microns.

It’s often thought of as sand blasting with baking soda. But there’s so much more to it than that, and to really appreciate the full capabilities of the process, a better understanding of the media and how to apply it is important.

Sodium bicarbonate (baking soda) is a broad-spectrum abrasive—from very gentle to moderately aggressive, depending upon particle size, blasting pressure, nozzle-to-part distance and other variables. Soda blasting offers several advantages from a process technology point of view. With the right equipment, it can be highly effective for cleaning surfaces and removing paints as well as epoxy and urethane coatings. The “spent” bicarb can then be easily dissolved with a subsequent hot wash cycle. This process is a nice option for industrial cleaning.

“I like to think of it as an emerging technology for the last 20 years,” says Charlie Ruemelin. He’s been working with baking soda blasting for that long, and he’s all too familiar with the arguments often offered against the technology. “If you try to blast in a standard cabinet with dry baking soda at any kind of normal production-level pressure, such as 60 to 80 psi, with conventional ventilation, you’ll be forced to stop in less than five seconds. The dust generated is unbelievable, so you won’t be able to see what you’re doing at all,” he explains.

Conventional ventilation struggles, and largely fails, to keep up with the dust, and without visibility, the process does not lend itself to any real commercial application. And that’s where many people give up on it. “Baking soda has unique attributes, but it also has unique obstacles for successful use,” Mr. Ruemelin says.

Mr. Ruemelin works on the hardware side of the business. He’s quick to point out the advances in the use of various nozzles with baking soda blasting. “You can do certain things with nozzles for baking soda that you can’t do with traditional media because baking soda won’t destroy the geometry of the nozzle,” he explains. “You can use wide fan nozzles or an extra long Venturi to accelerate the media. Wear on the nozzle is greatly reduced, and they sometimes last for years instead of days or weeks.” But it’s the solution to the ventilation issue that Mr. Ruemelin feels has been the biggest breakthrough.

In 1991, Mr. Ruemelin developed what he calls targeted, high-velocity ventilation. The necessary volume of ventilation air drawn into the cabinet is focused on the workpiece, thereby allowing a clear line of sight and unleashing the full benefits of baking soda blasting, particularly at higher blasting pressures.

Mr. Ruemelin has since licensed this technology, trademarked as ClearView, to Clemco Industries, manufacturer of air-powered abrasive blast equipment. It is now marketed as a feature of the company’s Aerolyte Bicarbonator soda blast cabinet, which is designed specifically for use with sodium bicarbonate media for degreasing, cleaning, and paint stripping applications.

Although Clemco is now carrying the technology forward, Mr. Ruemelin still serves as a spokesman, or as he says, “The Johnny Appleseed for the technology, continuing to plant the idea far and wide.”

“We’re trying to reach people who want a quick, effective coating removal solution and also recognize that moving away from hazardous solvents will help alleviate environmental health and safety issues in the workplace,” he says. “But we need to communicate clearly that it’s not just a drop-in solution. To do it right, you need to be committed to the full process and technology.” It’s also important that it is used for the right applications. Baking soda blasting can do some things extremely well in some cases, yet still might not provide a reasonable financial payoff.

To determine the proper payback equation, a number of factors must be considered between baking soda and other options: cost of the media (baking soda is a single-use media), disposal costs, processing speed, effectiveness and surface quality. Weighing all of these considerations together may provide a surprising outcome, and working with a company with experience in this area can help a potential user develop an accurate overall picture. Clemco offers a process laboratory that can do test work to compare baking soda and other kinds of abrasives to determine the most effective solution for a given application.

One success story is evident at General Dynamics Aviation Services, where baking soda blasting is being used on landing gear. Previously, the company used a semi-abrasive media at a low pressure to avoid damaging the under-coating. It took 30 to 40 hours to complete a landing gear set, and even then, care needed to be taken to remove the trapped media. Since implementing baking soda blasting, labor time for depainting the landing gear has been reduced by at least 75 percent. In this case, the payback period for the hardware was less than a year.

Mr. Ruemelin concludes, “Many high-value, complex-geometry parts have coatings that may have been applied incorrectly or must be removed as the first step in a remanufacturing operation. Many abrasive blasting technologies will damage the substrate in some fashion or cause crack closure or other undesirable results. You won’t get that with baking soda, and the abrasive itself is water soluble so you can clean up your mess!” PC

Supplying Soda

One of the more significant suppliers of sodium bicarbonate media is Natrium Products, Inc. Considered a niche company with a narrow focus on the soda blasting process, the company has taken large steps in helping to develop and promote this technology. The company’s marketing and sales manager, Tim Herman, points out that there are different segments to the soda blasting market that Natrium addresses. “Portable blasting is often used for graffiti and mold remediation,” he explains. “But for parts cleaning, the work is most often done in a cabinet.”

Natrium has had a relationship with Clemco Industries for more than 10 years, working together to find ways to advance the technology. Mr. Herman feels this relationship is important because of the features and quality that Clemco offers in its cabinets.

So how does one choose the best media for a given application? Mr. Herman says, “Unfortunately a lot of people will immediately default to the least expensive option, without giving full consideration to the productivity benefits of the others. And usually the productivity (time savings) of the material will easily outweigh the higher cost.”

When removing a coating, the coarser (larger) sodium bicarbonate crystals provide more momentum and energy and therefore will remove most coatings faster. The finer crystal is typically less expensive and is usually sufficient for cleaning applications. As the material strikes the surface, it shatters, creating dust. The coarser the product, the fewer fines there will be, so the easier it will be to see the work in the cabinet.

How the dust is handled by the cabinet is also an important consideration when choosing the best media. With Clemco’s targeted, high-velocity ClearView ventilation system, larger volumes of dust can be handled, allowing both practical use of the smaller crystals and higher blasting pressures. So a number of factors come into play for determining the best fit.

To address an assortment of needs, Natrium offers three different grades of crystals—150, 300 and 340 microns. Mr. Herman details, “Given the number of variables, a company should examine its options closely. It might appear a 340 is better until you put it into a system like Clemco’s that can considerably cut down on the dust. Then you might realize that a 150 was good enough. The 300 works well as a middle ground between price and efficiency, particularly for those who run a range of applications and prefer to keep only one size in stock.”