Wet/Abrasive Blasting Applications
Wet abrasive blasting can substitute for sandblasting for virtually any application, but there are surfaces, conditions and environments for which wet blasting is especially advantageous.
Dry blasting can cast dry sparks charged with static electricity which can lead to explosions in the presence of flammable gases. Wet blasting does not completely eliminate sparks, but when sparks occur they are cold sparks (without static electricity), minimizing the explosive potential.
Wet blasters can operate effectively at lower PSI, removing coatings without damaging the underlying substrate. Vapor abrasive blasting is a preferred method for blasting antique, fragile surfaces and soft surfaces (including wood). In addition, the presence of lubricating water reduces heat due to friction that can warp metal surfaces.
Dry blasting requires substantial containment/tenting to maintain airborne dust levels within legal limits. In outdoor and urban environments, such containment is not practical or cost-effective. Due to inherent dust suppression, vapor abrasive blasting operations require minimal containment.
Dust from dry blasting presents not only an inhalation health hazard, but severely limits visibility. Whereas dry blasting operations must be sequestered from normal operations, wet blasters can work in close proximity with other workers with minimal precautionary measures.
Graco Helps Start-Up Blasting Business Find First-Year Success
ECO Vapor Blasting Solutions, LLC, located in Atlanta, GA, is a growing company providing surface restoration and cleaning for the commercial, industrial, municipal and residential industries. Using Graco’s EcoQuip® Vapor Abrasive® blasting equipment, the company wrapped up a successful first year at the end of 2016, bringing safer, more effective and efficient.
What happens on impact
When abrasive impacts a hard surface, the particle often breaks or shatters, propelling finer particles into the air as dust, in addition to dust already present in the dry media. This impact can also cause dry sparks charged with static electricity.
When wet abrasive impacts a surface, fine particles are sequestered in water droplets. The additional water weighs the particles down, preventing dust.
The presence of water also confers more mass on the particle at impact. As the water droplet disperses, the hydrostatic force blasts away surface coating, leaving a feathered edge around the perimeter for seamless recoatings.
The Truth About Dustless Blasting
There is no such thing as “dustless” or “dust-free” blasting in the surface preparation industry. All abrasive blasting equipment operating under normal conditions produces dust.
Air quality studies have shown that the most effective vapor abrasive blasting machines suppress no more than 92% of dust produced by dry blasting. Manufacturers claiming that their equipment is “dustless” or “dust-free” may be misleading you.
When a particle of abrasive media shatters, it breaks down into sub-particles. The smallest sub-particles lack the mass to descend to the ground in the presence of air turbulence produced in the blasting process.
With a wet blasting process, the original particle is encapsulated to varying degrees in a water jacket. When the particle shatters upon impact, the ensuing wet sub-particles are weighed down by the water and gravity pulls them to the floor, despite the air turbulence.
However, some sub-particles are so small, that even though encapsulated in water they do not take on sufficient mass to counteract the force of air turbulence, and they linger suspended in the atmosphere. In addition, not all sub-particles are encapsulated in water jackets. Sub-particles emitting from the dry interior of the original particle may not become moistened at all. This is why no wet-based blasting system can completely eliminate dust.