If someone tells you to “just use sand,” that’s outdated. Aluminum is softer than steel and needs engineered blasting media chosen for the job you have: quick paint removal, a smooth satin look, or a clean surface that coatings can really grip. This page shows which media work on aluminum—garnet, crushed glass, glass bead, soda, walnut/plastic—when to use each, and simple grit/PSI starting points. We’ll also flag what to avoid.
What Blasting Media Does on Aluminum
- Cutting vs peening. Angular media like garnet and crushed glass cut the surface to raise “tooth” for paint or powder. Rounded glass bead peens, evening out reflections to create a uniform satin.
- Adhesion vs appearance. More cutting = stronger coating grip. More peening = prettier satin. Many shops do both: strip fast, then finish for looks or adhesion.
- Residue matters. Some gentle media (like soda, walnut) can leave residues. Clean them off before coating or anodizing.
Media You Can Use on Aluminum
- Garnet — Angular, stable sizing, great for fast stripping with decent recyclability.
- Crushed Glass — Angular, very fast stripping and budget-friendly; control dust and grading.
- Glass Bead — Rounded, best for uniform satin; if you need more “tooth,” add a light aluminum-oxide (AO) 120–150 pass afterwards.
- Soda — Ultra-gentle cleaning; almost no cutting. Good near mixed materials, but not enough tooth for durable coatings unless followed by a light AO pass.
- Walnut / Plastic — Very gentle for delicate parts; again, not for strong adhesion unless you follow with AO.
- Avoid on aluminum: Steel shot/grit (iron can embed → corrosion/coating failure) and silica sand (serious health hazard, inconsistent finish).
When to Use Each Media
| Goal | Recommended Media | Typical Grit | Start PSI | Expected Ra / Look | When to Add a Light AO Touch |
|---|---|---|---|---|---|
| Fast paint/clear removal | Garnet or Crushed Glass | 60–80 | 60–80 | Medium profile; strips quickly | If final Ra must be lower, make a light pass with AO 120–150 |
| Even satin appearance | Glass Bead | 80–120 | 40–60 | Smooth, uniform matte (often Ra ~0.6–1.2 μm) | If adhesion is borderline, add a quick AO 120–150 sweep |
| Residue-sensitive cleaning | Soda | 60–120 | 20–40 | Minimal cutting; safest near mixed materials | Rinse/clean thoroughly; add AO before coating if strong grip is needed |
| Very delicate or mixed materials | Walnut / Plastic | 60–120 | 20–40 | Very gentle; almost no “tooth” | Follow with AO if durable coatings are required |
Recyclability, Dust and Safety
| Media | Recyclability | Dust / Visibility | Safety Notes | Housekeeping Tips |
|---|---|---|---|---|
| Garnet | Medium–High | Low–Medium | Low free silica; stable grading | Keep air dry; sieve to maintain cut rate |
| Crushed Glass | Medium | Medium–High | Low free silica; can be dusty | Good dust extraction; check grading |
| Glass Bead | Medium | Low | Inert; static can attract dust | Ground equipment; keep bead clean and dry |
| Soda | Low | Medium | Residue must be removed before coating | Plan a thorough rinse/clean step |
| Walnut / Plastic | Low | Low–Medium | Organic/polymer dust; can carry static | Anti-static measures; diligent cleanup |
| Silica Sand | — | High | Do not use—respirable silica hazard | — |
| Steel Shot/Grit | High | Low | Not for aluminum—iron embedment risk | — |
How to Pick Grit and PSI by Media
| Media | Typical Grit | Start PSI | Standoff / Angle | Notes |
|---|---|---|---|---|
| Garnet | 60–80 | 60–80 | 150–250 mm / 70–90° | Fast stripping; decent recycle life |
| Crushed Glass | 60–80 | 60–80 | 150–250 mm / 70–90° | Very fast; refine later if you need lower Ra |
| Glass Bead | 80–120 | 40–60 | 150–250 mm / 60–80° | Uniform satin; avoid edge dwell |
| Soda | 60–120 | 20–40 | 150–250 mm / 60–80° | Gentle cleaning; add AO 120–150 if coating grip is needed |
| Walnut / Plastic | 60–120 | 20–40 | 150–250 mm / 60–80° | For delicate/mixed builds; little “tooth”—plan an AO follow-up if coating |
Troubleshooting by Media
- Patchy matte after bead → Normalize overlap (30–50%), keep PSI moderate, finish with a short leveling pass.
- Streaks after garnet/crushed glass → Check media grading and air dryness; if you need a smoother profile, do a brief AO 120–150 refinement.
- Coating chips after soda → Not enough tooth; add a light AO pass before primer/powder.
- Dusty booth, poor visibility → Upgrade extraction, keep media dry, sieve/replace as it breaks down.
- Unexpected corrosion spots → Make sure no steel media touched the part; remove all residues and fingerprints before coating.
FAQs
Is soda blasting enough before powder coat on aluminum?
No. Soda is great for gentle cleaning but leaves very little “tooth.” If you plan to powder, follow with a light aluminum-oxide 120–150 pass.
Garnet or crushed glass—which strips aluminum faster?
Both are quick. Crushed glass often cuts fastest on heavy coatings; garnet gives steady, repeatable stripping with good recyclability. Many shops keep both.
When should I choose glass bead instead of cutting media?
Choose glass bead when a uniform satin look is the main goal. If adhesion tests are marginal, add a light AO 120–150 sweep afterward.
Do walnut or plastic media work on aluminum?
Yes—for very delicate work or mixed materials where cutting would be risky. They do not create enough “tooth” for durable coatings unless followed by AO.
Why avoid silica sand or steel shot on aluminum?
Silica sand is a significant health hazard and gives inconsistent finishes. Steel media can embed iron and trigger galvanic corrosion or coating failures.
Need the same look, every lot?
We run 800–2000-ton aluminum die-casting lines with in-line deburr → blast (bead / AO / garnet / hybrid) → powder or anodize. For A380/ADC12/AlSi10Mg parts we deliver a defined Ra, a locked media × grit × PSI recipe, and inspection data—so every shipment looks the same and coatings stick.
→ Ask for a free “media × grit × PSI” starter for your part • → Upload a drawing or photos for a finish plan
