Dry blasting and wet blasting (also called slurry blasting or vapour blasting) are two cleaning methods used in several industrial and commercial applications.
While they both present valuable advantages over each other, they can also be interchanged in most applications. However, due to the higher cost of a wet blasting system, dry blasting is used by the majority.
Dry blasting uses compressed air to propel abrasive media at a high velocity onto the workpiece. A dry blasting environment involves a lot of dust, but this cleaning method delivers the best output for most applications.
Here are the advantages of dry blasting:
- Wide range of blast materials – dry blasting can handle pretty much any type of blast media without the risk of rust or corrosion.
- More aggressive blasting action – without any restrictions, the blast media stream can be propelled at a very high velocity onto the workpiece, resulting in faster cleaning rates and/or better surface preparation on most substrates.
- Cost-efficient – the acquisition cost of dry blasting equipment is usually lower than that of wet blasters.
- Versatility – dry blasting equipment is suitable for a wide range of applications from high-volume production, to surface preparation, and occasional maintenance on equipment and tools.
Wet Blasting (Slurry blasting / Vapour blasting)
In wet blasting, a mixture of water and abrasive media is propelled onto the workpiece. The main advantage of slurry blasting is that it produces a smoother finish since the water washes away abrasive residues and dust upon impact and prevents them from becoming encrusted in the surface.
The water/abrasive mixture is usually kept moving while the blaster is on for a quick blasting action. The water/media ratio must be kept intact by evacuating excessive amounts of water from the mixture.
The addition of water to the mixture provides significant advantages over regular dry blasting:
- Low dust blasting – blast residues are flushed out by the water, resulting in a less dusty process than regular dry blasting. Also, the water softens the abrasive media’s impact onto the workpiece, preventing the media from shattering into dust.
- Softer finish on most surfaces – the water acts as a cushion to soften the impact of the abrasive media onto the workpiece and flushes away the media particles, resulting in a smoother, satin finish. In regular sandblasting, the impact is usually more aggressive and media particles could impregnate themselves into the blasted surface, resulting in a rougher finish. Wet blasting is usually preferred to clean the surfaces of softer materials that need to be preserved, such as plastic or soft aluminum alloy.
- Uses finer abrasive media – water is a better carrier of finer mesh abrasive media than air. Therefore, wet blasting is usually preferred when the application involves very fine abrasive media.
- No static charges – water dissipates the buildup of static electricity. Vapor blasting does not completely remove static charges, but it generates cold charges rather than sparks, eliminating the risk of fire or explosion in cases where flammable materials, gases, or dust are present.
- Degreasing applications – while greasy and oily contaminants removed from the surface mix with dry abrasive and may cause a blockage or rust in critical components of dry blasting equipment, wet blasting is designed to withstand wet contaminants and can be effective when cleaning parts that are partially greasy or oily. This eliminates an extra cleaning process and increases productivity on such applications, which is why wet blasting is often used to refurbish motors and compressor parts.