TABLE 1. Hardness, shape and some of the particle sizes available for the most popular airbrasive powders.

Air-abrasive Powder Hardness
(Mohs)
Shape Available Particle Size
(μm)
Aluminium oxide 9 Blocky and sharp 10-150
Silicon carbide 9 Blocky and sharp 20-50
Glass beads 6 Spherical 35-100
Crushed glass 5-6 Blocky and sharp 50-75
Pumice 6 Blocky and sharp 75
Dolomite 3.5-4 Blocky 150
Plastic 2-4 Blocky 50-200
Walnut shell 3-4 Blocky 250
Sodium bicarbonate 3-4 Monoclinic 50-100
Wheat starch 2 Lenticular and spherical 100

 

 

TABLE 2. Elements incorporated into blast cabinets. * Of the remainder (66.7%) who responded negatively, 58.7% said they wore protective gloves.

Element/Equipment % Responders
Dust Extraction/venting 98.3
Integral lighting 84.5
Magnifying lens 60
Integral gauntlets 33.3 *

 

TABLE 3. The results of the trench scatter tests.

Powder Angle Working distance
(mm)
Scatter width
(mm)
Scatter length
(mm)
Trench depth
(μm)
Aluminium oxide (10 μm) 30 30 8.58 16.42 450
Aluminium oxide (50 μm) 30 30 7.9 16.94 50
Aluminium oxide (50 μm) 30 15 7.57 12 375
Aluminium oxide (50 μm) 15 30 8.39 26.23 <10
Aluminium oxide (50 μm) 45 30 11.23 16.1 100
Aluminium oxide (50 μm) 90 30 11.73 11.79 500
Crushed glass (50 μm) 30 30 6.85 13.37 375
Crushed glass (50 μm) 45 30 6.96 13.32 430
Glass bead (50 μm) 30 30 8.73 14.93 350
Pumice (50 μm) 30 30 8.31 14.01 75
Silicon carbide (50 μm) 30 30 1.31 17.76 425
Sodium bicarbonate (50 μm) 30 30 6.06 11.06 30
Plastic (50 μm) 30 30 5.54 9.63 20