Finishing
Bead Blasting vs Sand Blasting
Bead blasting drives spherical glass media against the surface to peen and clean it, leaving a soft satin finish with almost no material removal. Sand blasting uses angular abrasive, typically aluminum oxide or garnet now that silica is restricted, to cut the surface fast and leave an anchor profile for coatings.
| Bead Blasting | Sand Blasting | |
|---|---|---|
| Media | Glass bead, 60 to 120 mesh | Aluminum oxide or garnet, 30 to 80 grit |
| Finish result | Uniform satin, Ra 0.8 to 1.6 µm | Anchor profile 1.5 to 4 mil |
| Material removal | Near zero, peening action | 0.01 to 0.1 mm, cuts base metal |
| Blast pressure | 40 to 80 psi | 80 to 120 psi |
| Coverage rate | 1 to 3 ft2/min light cleanup | 3 to 10 ft2/min on scale and rust |
| Media cost and life | $1.00 to $1.50/lb, 8 to 10 recycles | $0.50 to $2.00/lb, 4 to 8 recycles |
| Typical use | Cosmetic finish, pre anodize | Coating prep, scale and rust removal |
Choose Bead Blasting when
- Cosmetic satin finish on aluminum or stainless
- Thin walls or tight tolerance parts
- Uniform matte surface before anodizing
Choose Sand Blasting when
- Rust, mill scale, or old coating removal
- Anchor profile for paint or powder coat
- Fast cleanup on heavy weldments
The verdict
These are not interchangeable. Bead blast for appearance and pre anodize work where dimensions must hold; blast with aluminum oxide or garnet for scale removal and coating prep where you need a 2 to 4 mil profile. Never run actual silica sand; OSHA silica exposure limits make it a liability.
Cost comparison
Cabinet bead blasting a small machined part runs $2 to $8 in labor at 1 to 3 ft2/min, and glass bead at $1.25/lb survives 8 to 10 recycles. Aluminum oxide blasting for coating prep runs $1 to $3 per ft2 in a shop, double or more in the field. Masking and handling drive 30 to 50 percent of most jobs. Match media to the requirement; a thin wall part cut 0.1 mm deep by the wrong grit costs the whole part.
Common questions
Can I bead blast before powder coating?
You can, but adhesion suffers. Glass bead leaves a smooth peened surface around Ra 1 µm with almost no anchor profile, and powder coat specs typically want 1.5 to 3 mil of profile. Use 80 grit aluminum oxide for prep and save the bead cabinet for cosmetic work that will stay bare or get anodized.