Abrasive Blast Media Selection Chart by Material and Application

1. Carbon Steel — Structural and Industrial

Carbon steel is the most common blasting substrate worldwide and the one for which the widest range of media options exists. The selection decision is driven primarily by equipment type and production volume. For automated wheel-blast facilities — shipyards, structural fabricators, rail car manufacturers — steel grit in the G-25 to G-40 range is the near-universal standard. It delivers profiles of 2.5–4.0 mils to meet SSPC-SP 10 specifications, recycles 100–300+ times in closed-loop systems, and generates minimal dust inside enclosed blast rooms.

For field blasting — bridges, pipelines, storage tanks — pressure blast with aluminum oxide F20–F36 or garnet 16–30 is standard. The choice between them depends on dust tolerance at the site: AO blasts faster and costs less per ton; garnet generates significantly less dust and is preferred in populated areas, over waterways, or where containment of blast debris is difficult.

The surface profile required for carbon steel is determined by the coating system. Confirm requirements from the coating TDS before selecting grit size. For detailed profile-to-media mapping, see our surface profile chart and anchor pattern guide.

2. Stainless Steel

The defining constraint for stainless steel blasting is iron contamination. Any media that contains metallic iron — steel shot, steel grit, recycled blended media, or even contaminated mineral abrasives previously used on carbon steel — will embed iron particles in the stainless surface. These embedded particles will rust and bleed through any subsequent coating, destroying the aesthetic appearance and potentially compromising the corrosion performance of the stainless substrate.

Glass beads are the standard for stainless steel applications requiring a clean, bright satin finish — pharmaceutical equipment, food processing vessels, architectural panels, and decorative fittings. They create a uniform peened finish without a high anchor profile and carry no iron contamination risk. For stainless that requires a surface profile for coating adhesion — such as stainless pipe being painted in a chemical plant — garnet (very low iron mineral) or white fused aluminum oxide (99.5%+ Al₂O₃, zero iron) are the correct choices. Never use brown fused aluminum oxide, which contains trace iron oxide that can contaminate stainless surfaces.

3. Aluminum and Non-Ferrous Metals

Aluminum presents two critical constraints that eliminate most media types used on steel: first, its relatively low hardness (Brinell 15–100 depending on alloy and temper) means that hard angular mineral media will erode the aluminum surface, changing dimensions and potentially initiating stress cracks in fatigue-sensitive components. Second, contamination with iron particles from steel-derived media will cause galvanic corrosion under any subsequent coating.

Plastic abrasive grit — in melamine (Mohs ~4), urea (Mohs ~3.5), or polyester formulations — is the solution for stripping coatings from aluminum without these problems. Its hardness is below aluminum at most tempers, making it physically incapable of eroding the base metal while still being hard enough to strip organic coatings efficiently. For aerospace applications involving fatigue-critical aluminum components, the specific plastic grit type, grit size, blast pressure, and exposure time must be validated against the relevant aircraft maintenance manual (AMM) and process specification (Boeing BAC 5748, Airbus AITM 4.0016, etc.). Media must be virgin — never recycled or previously used on steel — to prevent cross-contamination.

4. Cast Iron and Foundry Parts

Cast iron foundry work represents one of the highest-volume blasting applications globally. Freshly poured castings carry foundry sand, oxide scale, and metallurgical surface irregularities that must be removed before inspection, machining, or coating. Wheel-blast systems using steel shot in the S-230–S-460 range are the industry standard for this application — they clean castings at very high throughput rates, peen the cast surface to improve its fatigue characteristics, and achieve 100–300+ reuse cycles in automated equipment.

When cast iron parts require painting or coating, steel grit G-40–G-50 provides the angular anchor profile needed for coating adhesion while maintaining the high recyclability advantage of metallic media. For smaller runs in cabinet systems, aluminum oxide F36–F60 is effective. Cast iron’s graphite microstructure makes it more brittle than steel and more susceptible to chipping under very aggressive blast conditions — use the coarser end of the recommended range only when the casting geometry and wall thickness support it.

5. Concrete and Masonry

Concrete surface preparation for industrial coatings — epoxy floors, polyurethane overlays, cementitious waterproofing — requires achieving a specific Concrete Surface Profile (CSP) as defined by ICRI Guideline 310.2. Most heavy-duty coating systems specify CSP 3–5, which corresponds to a moderately to aggressively textured surface with visible pores open and laitance removed. CSP 3 is achievable with F24 aluminum oxide at moderate pressure; CSP 4–5 requires F16–F20 or, for high-throughput floor areas, a dedicated floor shot-blast machine using steel shot S-330–S-390.

Floor shot-blast machines are the most efficient option for large horizontal concrete surfaces — they are self-contained, contain all blast debris internally, and can prepare 300–600 m² per hour at production settings. Garnet 16–24 is used when the environment is occupied or near food production areas where mineral dust must be minimized, trading some speed for lower airborne particle levels.

6. Wood and Timber

Abrasive blasting of wood is a specialist application that requires organic, biodegradable media soft enough to remove coatings and surface contamination without damaging the underlying wood fiber structure. Walnut shell grit (Mohs 4.5–5) and corn cob grit (Mohs 4–4.5) are the established choices. Both are available in a range of mesh sizes — coarser grades for faster coating removal, finer grades for delicate or decorative timber where surface quality is paramount.

Blast pressure is the most critical variable when blasting wood. Standard mineral media pressures (80–100 psi) will fray, furrow, and permanently damage wood grain even with the softest media. Effective wood blasting uses pressures of 35–60 psi with walnut shell or corn cob. At these pressures, old paint and weathered wood fiber are removed while sound wood below remains intact. This technique is used widely in historic building preservation, log home restoration, and removal of lead-based paint from wooden architectural elements. Both media generate biodegradable waste that can typically be composted or disposed of without hazardous waste classification.

7. Glass and Natural Stone

Glass and natural stone (granite, marble, limestone, sandstone) are among the hardest materials blasted in non-industrial applications. Both require media harder than the substrate itself to produce a controlled cutting action. Silicon carbide at Mohs 9–9.5 is the only commercially available blast media hard enough to cut glass cleanly and engrave granite efficiently. Its extremely sharp cutting edges produce crisp, well-defined edges on etched patterns — critical for monument lettering, architectural signage, and artistic glasswork.

Aluminum oxide F80–F120 provides a more economical alternative for applications where etching precision is less critical — large-area glass frosting, texture work on softer stones (limestone, sandstone), and volume production of frosted glass panels. AO produces slightly less crisp edge definition than silicon carbide on glass but costs significantly less per ton. Blast cabinet systems with precision pressure regulators and stencil-compatible blast guns are the standard equipment for both glass and stone etching work. Dedicated ventilation systems and full respiratory protection are essential — fine glass and stone dust is a serious respiratory hazard.

8. CFRP Composites and Aerospace Materials

Carbon fiber reinforced polymer (CFRP) composite panels used in aerospace, automotive motorsport, and defense applications present the most demanding media selection challenge in industrial blasting. The carbon fiber reinforcement within the composite laminate is structurally critical and cannot be touched by the blasting process. Even minor erosion of the surface resin layer can expose fiber, alter fiber orientation, or initiate delamination — all of which constitute structural damage requiring panel replacement or complex repair.

Plastic abrasive grit — specifically urea formaldehyde (Mohs ~3.5) or polyester types — is the only media capable of removing aircraft topcoat and primer without eroding the underlying CFRP. At the relatively low blast pressures used (40–70 psi), plastic grit fragments progressively on impact, transferring its energy to the coating above the composite surface while generating insufficient force to disturb the harder, denser carbon fiber below. The specific validated media type, size, blast pressure, nozzle distance, and pass count for any given aircraft type must be drawn from the aircraft manufacturer’s Structural Repair Manual (SRM) or the appropriate MRO process specification — never selected generically. For glass-fiber reinforced plastic (GRP), walnut shell is also effective and offers a lower-cost alternative where the fiber preservation tolerance is less tight.

9. Galvanized and Pre-Coated Steel

Hot-dip galvanized steel presents a specific challenge: the zinc coating that provides its corrosion protection is itself relatively soft (Mohs 2.5) and will be rapidly removed by any media harder and more aggressive than glass beads or plastic grit. The goal in most galvanized steel blasting scenarios is to lightly activate or clean the zinc surface — removing white rust (zinc carbonate), contamination, or excessive zinc spangle — while retaining the galvanic protection the zinc layer provides.

Glass beads at 80–120 mesh applied at reduced pressure (50–70 psi) achieve this by peening the zinc surface gently, removing superficial contamination and improving coating adhesion without significant zinc removal. When the galvanized steel is being completely repainted and the residual zinc will be supplemented by a zinc-rich primer in the new coating system, a light scuff with plastic grit at 20–40 mesh provides an adequate adhesion surface without compromising the remaining zinc thickness. Hard mineral media or any form of steel abrasive will strip zinc entirely and must not be used when zinc preservation is required.

10. Marine and Offshore Steel

Marine and offshore blasting imposes a specific combination of requirements that makes media selection more constrained than most industrial applications. Hulls and offshore structure sections must be prepared to Sa 2.5 (SSPC-SP 10 Near-White Metal) or better for anti-corrosion coating systems designed for seawater immersion service — demanding profiles of 2.5–4.0 mils and complete removal of all rust, mill scale, and old coating. At the same time, the near-water location creates strict requirements on media dust levels, heavy metal leachability in residue, and waste classification.

Garnet has become the predominant choice for marine pressure-blast work outside enclosed facilities precisely because it meets both requirements simultaneously: its sub-angular geometry achieves profiles of 2.5–3.5 mils on structural steel, its very low free silica content minimizes health risk, and its low leachable heavy metal levels (typically below detection limits for arsenic, lead, beryllium) make spent media disposal straightforward in most port jurisdictions. Steel grit G-18–G-25 remains the preferred media inside enclosed shipyard blast halls with full media recovery systems, where the cost advantage of metallic media’s recyclability outweighs the logistical simplicity of garnet in open settings.