Sand Blasting & Bead Blasting Finish

What it is and when to specify it

Sand blasting, also called abrasive blasting or bead blasting when glass bead is the medium, propels a stream of abrasive grit against a machined surface with compressed air. The grit scours the top layer, removing machining marks, tool lines, light oxidation and shop grime, and leaves an even matte finish. It is a mechanical surface treatment, not a coating: it changes texture rather than adding a film.

You specify sand blasting when a part needs a uniform satin look, when it must be cleaned before coating or plating, or when a surface has to be keyed so paint, powder or an adhesive will bond. It is common on aluminium enclosures, brackets, housings and hardware where a bright machined face is not wanted, and where the finish should look consistent across the whole batch.

For parts that will be coated, blasting gives the surface a micro-roughness that a smooth machined face does not provide. That keying is why many painted and powder coated aluminium parts are blasted before they are coated.

Specifications

The main decision is the grit type and the resulting finish, not a coating thickness. Common media are glass bead, aluminium oxide, garnet and steel grit. Glass bead produces a softer, satin finish and is the usual choice for aluminium. Aluminium oxide and garnet cut more aggressively and are used to remove heavier scale or to key steel before coating. Steel grit is reserved for ferrous parts where a coarser profile is wanted. Grit size is selected per part so the finish is uniform without damaging fine features.

Finish is described as a matte or satin texture, and surface roughness is set by the drawing where it matters. We match the grit and pressure to the material and the required look, then confirm the result on a sample where appearance is critical. Masking is available for threads, bores, sealing faces and other features that must stay untouched.

The process runs through our vetted partner network, managed under one quality process, so you keep a single point of contact and one set of documents for the whole order.

Which materials and parts it suits

Sand blasting works across our metal range: aluminium in 2024, 5052, 6061 and 7075; stainless steel in 301, 303, 304, 316 and 17-4PH; carbon and alloy steel in 1045, 1215, 4140, D2 and O1; plus brass, copper, bronze and titanium. Each takes a slightly different grit and pressure, but the result is the same even matte surface. Grade detail lives on our materials index, then aluminum parts, stainless steel parts, steel parts, brass and copper parts and titanium parts pages.

Typical parts are enclosures and housings, custom brackets, knobs, panels and hardware that will be seen or handled. Blasting is also a standard prep step before anodizing, powder coating or plating, where the blasted profile helps the coating bond. The full finish range is on our surface finishes page.

Corrosion, wear and dimensional impact

Blasting does not add a protective layer the way anodizing or plating does. On its own a blasted surface keeps the corrosion behaviour of the base metal, and the increased surface area can hold moisture slightly more than a polished face, so exposed steel parts are usually coated after blasting. The real benefit is preparation: a blasted and then coated part holds its coating far better than a smooth one.

The main engineering concern is dimensional. Blasting is mildly abrasive, so sharp edges soften, fine details can round, and the texture adds a little roughness. Threads and precision bores must be protected, which is why we mask them. On a drawing we review which features carry a tight tolerance and make sure blasting either avoids them or that the finishing allowance still holds ±0.01 mm on the machined features that matter.

Blasting is not shot peening. Shot peening uses rounded media at higher energy to deliberately cold-work the surface into compressive stress for fatigue life, while blasting is about cleaning and texture. If your drawing specifies peening, tell us, and we will route it to the correct partner process rather than treating it as a cosmetic blast.