Best Blasting Media to Remove Rust on Steel and Aluminum

People often say “just sandblast it,” but removing rust properly depends on what the part is made of and what coating you’ll apply next. Steel and aluminum are very different: steel forms red rust; aluminum does not—it forms white/grey oxidation and sometimes pitting. This guide shows what rust removal really requires, why media must differ for steel vs aluminum, and how to choose media, grit, and PSI so you get fast removal and a surface that coatings can grip.

What Rust Removal Really Needs on Steel and on Aluminum

• Steel
  Steel rust is iron oxide that can be flaky or deeply bonded. To refinish properly, you need to:
  1. Remove rust and mill scale completely (not just make it look cleaner), and
  2. Create an “anchor profile”—a fine roughness so primer or powder can lock in.
     If the profile is too low, coatings chip easily. If it’s too high, you waste coating, trap air, or get orange peel.
• Aluminum
  Aluminum doesn’t make red rust. It forms a natural oxide layer (and in harsh use, pitting or white corrosion). For aluminum, blasting is about:
  1. Removing oxidation and contaminants, and
  2. Setting a controlled surface that either looks good (satin) or has enough “tooth” for paint/powder/anodize.
     Aluminum is softer; the wrong media can embed contamination or cut too aggressively.

Why Media Choice Must Differ Between Steel and Aluminum

• Steel tolerates steel media. On steel, steel shot (S) and steel grit (G) are common, fast, and recyclable. They can deliver an excellent profile for heavy-duty primers.
• Aluminum must avoid steel media. On aluminum, steel shot/grit can embed iron into the surface, which later corrodes and ruins coatings. Aluminum also should avoid silica sand because of health risks and poor finish control.
• Use engineered media on aluminum. For aluminum, rely on aluminum oxide (AO), glass bead, garnet, or crushed glass. Gentle media like soda or walnut/plastic are for delicate cleaning, but usually need a light AO pass afterward if you’ll coat.

How to Remove Rust from Steel Step by Step

Tools and Materials

• Blasting cabinet or booth with dust extraction
• Compressor with dry air (water trap + desiccant)
• Nozzle (check wear; replace if the orifice is oversized)
• Media: steel grit G25–G40 (heavy rust), garnet 36–60 (heavy), garnet or crushed glass 60–80 (general), fine garnet 80–120 (flash rust)
• Clean rags, solvent or alkaline degreaser, masking tape/caps
• Primer system ready (epoxy or zinc-rich primer)

Safety Checklist

• Blast helmet, gloves, protective clothing, hearing protection
• Ventilation running and dust collector purged
• Grounding straps on equipment to control static
• Confirm no silica sand in your media supply

Set Up the Area

1. Dry the air supply; drain receivers and check filters.
2. Sieve or refresh media; log current nozzle size.
3. Arrange stands so you can walk all sides without stopping.

Step 1 Diagnose the Rust

• Heavy rust or mill scale: thick, flaky, black or blue scale.
• General rust: brown/red oxide, occasional pitting.
• Flash rust: light orange film after washing or humidity.

Step 2 Choose the Media

• Heavy: steel grit G25–G40 (fastest, recyclable) or garnet 36–60.
• General: garnet 60–80 or crushed glass 60–80.
• Flash: fine garnet 80–120.

Step 3 Prepare the Part

1. Degrease thoroughly.
2. Mask threads, bearing seats, machined faces.
3. Position the part so edges are easy to pass without dwelling.

Step 4 Dial In the Settings

• Start PSI: 70–100 PSI for steel.
• Standoff: 150–300 mm.
• Angle: 70–90°.
• Traverse: steady, with 30–50% overlap.
• Tip: tune standoff → angle → travel speed first, then adjust PSI.

Step 5 Blast Technique

1. Make a light, even “proof pass” to see coverage.
2. Work from edges inward; never park the nozzle on corners.
3. Keep the hose straight; avoid whipping the nozzle.
4. Check one small area to confirm rust is fully removed and profile looks right.

Step 6 Inspect the Surface

• No visible rust or scale, uniform grey metal.
• Target profile suits your primer (coating datasheet).
• Blow down all pockets; no media trapped.

Step 7 Prime Without Delay

1. Wipe clean and keep gloves on.
2. Prime as soon as practical (epoxy or zinc-rich).
3. In humid shops, use dehumidified space or temporary passivation per spec.

Common Mistakes and Fixes

• Flash rust returns quickly: dry the part, reduce time to primer, control humidity.
• Orange peel later: profile too high—use finer media or reduce PSI, check film build.
• Poor adhesion: profile too low or contamination—raise tooth slightly, re-clean, re-prime.

How to Remove Corrosion from Aluminum Step by Step

Tools and Materials

• Blasting cabinet or booth with dust extraction
• Compressor with dry air (very important for aluminum finish)
• Nozzle in good condition
• Media: crushed glass 60–80 or garnet 60–80 (fast strip), aluminum oxide 100–150 (adhesion), glass bead 80–120 (satin look)
• Clean rags, solvent/alkaline cleaner, masking tape/caps
• Coating system ready (primer + powder/paint) or anodize line

Safety Checklist

• PPE as above; avoid cross-contamination from steel areas
• Strictly no steel shot/grit and no silica sand
• Keep handling with gloves after blasting

Set Up the Area

1. Dry the air; moisture causes streaks and patchy matte.
2. Use clean, graded media; separate aluminum jobs from steel jobs.
3. Arrange soft supports to avoid denting thin sections.

Step 1 Identify the Condition

• Heavy coating or oxide build-up
• General oxidation and staining
• Cosmetic refinish where appearance matters most

Step 2 Choose the Media

• Fast strip: crushed glass 60–80 or garnet 60–80.
• Max adhesion for coating: aluminum oxide 120–150 (100–150 band).
• Uniform satin look: glass bead 80–120 (can add a light AO touch if adhesion is critical).

Step 3 Prepare and Mask

1. Degrease thoroughly; rinse and dry.
2. Mask threads, bores, sealing faces, and delicate edges.
3. Plan your passes so you never dwell on thin ribs or edges.

Step 4 Dial In the Settings

• Start PSI: 40–80 PSI depending on media.
• Standoff: 150–250 mm.
• Angle: 60–80°.
• Overlap: 30–50% for even matte.
• Tip: aluminum cuts quickly—favor technique over high pressure.

Step 5 Blast Technique

1. For fast strip, do a quick pass with crushed glass/garnet to remove coatings.
2. For final finish, switch to glass bead (satin) or AO (adhesion).
3. Keep the nozzle moving; never park on edges or thin spokes.
4. Confirm even coverage under consistent light.

Step 6 Inspect the Surface

• Satin goal: uniform, no shiny glare or streaks.
• Adhesion goal: clean, consistent tooth (AO), no embedded debris.
• Blow out all holes and pockets; remove masking carefully.

Step 7 Coat Within the Window

1. Blow down and wipe; handle with gloves only.
2. Prime and powder/paint within 4–24 hours.
3. For anodize: prefer white AO 120–150 and transfer promptly to pretreatment.

Common Mistakes and Fixes

• Shiny glare patches: lower PSI, increase standoff, even the overlap; switch to finer bead.
• Patchy matte: dry the air, sieve media, standardize passes.
• Poor coating adhesion: add a light AO 120–150 touch after bead; coat within the time window.
• Unexpected corrosion spots: check for steel contamination and fingerprints; keep tooling and benches clean.

Which Media When: Steel vs Aluminum

Use this table to match substrate and rust/corrosion level to a media choice that removes the problem and leaves the right surface for coatings.

Media Selection at a Glance

Substrate	Rust / Corrosion Level	Recommended Media	Typical Grit	Start PSI	Expected Profile / Look	Notes and Aftercare
Steel	Heavy rust or mill scale	Steel grit G25–G40 or Garnet 36–60	G25–G40 / 36–60	80–100	Aggressive cut, high profile	Prime quickly (epoxy or zinc-rich); control dust
Steel	General rust	Garnet 60–80 or Crushed Glass 60–80	60–80	70–90	Clean metal, moderate profile	Good base for most primers; verify target profile
Steel	Flash rust	Fine Garnet 80–120	80–120	60–80	Light clean-up, low profile	Avoid over-profiling; prime soon to stop return
Aluminum	Heavy coating/oxide	Crushed Glass 60–80 (strip) → AO 120–150 (refine)	60–80 → 120–150	60–80 → 45–70	Fast strip → controlled tooth	Avoid steel media; clean thoroughly
Aluminum	General clean for coating	AO 100–150	100–150	45–70	Sharper micro-profile	Great for primer/powder; test adhesion
Aluminum	Cosmetic satin	Glass Bead 80–120	80–120	40–60	Uniform satin, lower Ra	For higher adhesion, add a light AO 120–150 pass

Recommended Grit and PSI Starters

Grit & PSI Starters (Steel vs Aluminum)

Substrate	Media Family	Typical Grit	Start PSI	Standoff / Angle	Notes
Steel	Steel grit (G)	G25–G40	80–100	150–300 mm / 70–90°	Heavy rust/scale removal; highly recyclable
Steel	Garnet	36–80	70–100	150–300 mm / 70–90°	Broad use; stable grading
Steel	Crushed Glass	60–80	70–100	150–300 mm / 70–90°	Fast, economical; verify profile
Aluminum	Aluminum Oxide	100–150	45–70	150–250 mm / 60–80°	Adhesion before primer/powder/anodize
Aluminum	Glass Bead	80–120	40–60	150–250 mm / 60–80°	Uniform satin; lower Ra
Aluminum	Garnet / Crushed Glass	60–80	60–80	150–250 mm / 70–90°	Quick strip; refine with AO if needed

Recyclability, Dust and Safety

Recyclability & EHS

Media	Recyclability	Dust / Visibility	Safety Notes	Housekeeping Tips	Use on Steel	Use on Aluminum
Steel Shot/Grit	High	Low	For steel only	Track nozzle wear; keep dry	✅	❌
Garnet	Medium–High	Low–Medium	Low free silica	Keep air dry; sieve media	✅	✅
Crushed Glass	Medium	Medium–High	Low free silica; can be dusty	Good extraction; grading checks	✅	✅
Glass Bead	Medium	Low	Inert; static possible	Ground equipment; keep dry	—	✅
Aluminum Oxide	High	Medium	Hard, consistent cut	Manage dust; dry air; screens	—	✅
Soda	Low	Medium	Residue must be removed	Plan rinse/clean steps	✅	✅ (cleaning only)
Silica Sand	—	High	Do not use—health hazard	—	❌	❌

What to Do After Blasting

• Steel: Keep parts dry and clean. If you rinsed or washed, dry immediately to prevent flash rust. Apply the primer promptly—many systems use epoxy or zinc-rich primers over blasted steel. If your spec allows, a phosphate or passivation step can add corrosion resistance.
• Aluminum: Prime, powder, or anodize within 4–24 hours of blasting. Handle with gloves only. If you must wait, bag parts dry with desiccant and re-wipe before coating. For anodize, ensure the blast leaves a clean, uniform profile (white AO 120–150 is common).

Troubleshooting Steel and Aluminum

• Rust “comes back” quickly on steel → Part wasn’t dry or was left uncoated too long. Improve drying; control humidity; prime sooner.
• Coating chips easily → Profile too low or contamination present. Increase tooth slightly (coarser or AO touch), clean thoroughly, re-prime.
• Orange peel texture → Profile too high or coating too thick/over-baked. Refine blast (finer media) and check film build/cure.
• Patchy matte on aluminum → Inconsistent overlap/pressure or dirty media. Standardize passes, keep PSI moderate, clean/grade media.
• Shiny spots on aluminum (glare) → PSI too high or edge dwell. Lower PSI, increase standoff, keep the nozzle moving.
• Unexpected corrosion on aluminum → Steel media contamination or fingerprints. Never use steel media; handle with gloves and clean before coating.
• Media trapped in holes/threads → Improve masking; blow down from multiple angles; never coat over trapped media.

From Rust Removal to Die-Cast Finishing

If you need consistent results at scale, we run 800–2000-ton aluminum die-casting lines with in-line deburr → blast (AO / bead / 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 rust-removal media plan for your part • → Upload a drawing or photos for a finish spec

FAQs

What is the best media to remove heavy rust on steel?
For thick scale and deep rust, steel grit G25–G40 is fast and recyclable. If you don’t run steel media, garnet 36–60 also removes heavy rust efficiently.

Should I use steel shot or steel grit on steel?
Shot (S) peens and cleans with a rounded shape; grit (G) cuts more aggressively with angular edges. For heavy rust removal and profile, grit is usually preferred.

What media works for light flash rust on steel?
Use fine garnet 80–120 or crushed glass 80. You want to clean without creating an unnecessary high profile.

Can I use the same rust-removal media on aluminum?
No. Do not use steel shot/grit on aluminum—iron can embed and later corrode. Use AO, glass bead, garnet, or crushed glass depending on your goal.

Bead or AO on aluminum if I plan to powder coat?
AO (120–150) gives stronger adhesion. If you prefer the bead look, you can bead first for satin, then add a light AO pass to raise tooth.

What grit removes rust fast without hurting adhesion later?
On steel, garnet/crushed glass 60–80 is a good balance. On aluminum, AO 120–150 is a common sweet spot before primer/powder.

How do I prevent flash rust on steel after blasting?
Keep humidity low, avoid water/oil contamination, and prime quickly. If required by spec, use phosphate or zinc-rich systems for extra protection.

Why is silica sand a bad idea for rust removal?
It’s a serious health hazard (respirable silica) and its grading/shape make finishes inconsistent. Use engineered media with dust control and proper PPE.