WET BEAD BLASTING
Alternatively known as vapour blasting or aqua-blasting, wet bead blasting has some distinct advantages over dry bead blasting.
It is a less costly process because it requires lower air pressure and fewer CFM as the bead/water slurry is pumped to the blast gun while dry blasting requires higher pressure and CFM to produce the vacuum developed in the blast gun’s venturi to draw the media up to the gun. Lower pressure means reduced electricity consumption, less machine wear and less media breakage.
the media is suspended in water so no dust is produced and there is no need for vacuum systems and filters. Parts cannot overheat because the water cools the workpiece, meaning thinner sections may be blasted without distortion. The slurry jet obviates the need to earth the component to eliminate static shock.
Finally, wet bead blasting is recognised to produce a more aesthetically pleasing finish and the process can be controlled to produce different finishes.
DRY ABRASIVE BLASTING
Abrasive blasting is used to clean surfaces of contaminants (eg corrosion or paint) and etch them to aid adhesion of a subsequent layer such as paint or powder coating.
There are many types of abrasive media such as crushed glass, garnet, aluminium oxide and silicon carbon with differing properties of hardness, toughness, aggression etc. We use medium grade crushed glass for removing paint from steel prior to painting or powder coating where the etched surface encourages adhesion.
Where soft metals have been heavily corroded and caked in burnt-on oil, a pre-blast with fine aluminium oxide at low pressure removes all the contamination leaving a finely honed or etched finish which can then be peened with glass beads to a lustrous finish.
Crushed glass has one drawback: its useful life is limited as the sharp corners of the glass particles get worn down and the particles themselves fracture so it becomes less effective. Also, we regularly change our glass media because free iron particle contamination from blasting ferrous metals causes corrosion of stainless steel.