Anodizing and Bead Blast That Skip the Polishing Step
Appearance parts are judged on the first one and rejected on the eleventh. Our default is a 180# bead blast applied straight to the machined surface, then anodized — no polishing, no buffing marks under the anodic layer.
- Default texture
- 180# bead blast
- Polishing
- Not required
- Colors
- Clear, black, custom
- Approval
- Physical chip
Why we bead blast before anodizing, not polish
Polishing is the step that makes anodized aluminum look expensive — and the step that makes it inconsistent. A polished surface hides scratches until the anodic layer is applied, then highlights every polishing direction, every wheel mark and every handling scuff.
A 180# bead blast produces a uniform matte that behaves predictably. The texture is the same across the face, edges and machined pockets, and it stays the same from lot to lot. It also removes the need for a polishing operation, which shortens the route and removes a variable.
For a housing that will be handled, matte also hides fingerprints. That is not a cosmetic detail — it is why the finish survives contact with a customer.
Finishing facts
- 180# bead blast, no polishing before anodizing
- Anodizing in clear, black or custom colour
- Colour approved on a physical chip before production
- Also: sand blast, brushing, powder coating, laser marking
- Finish decision taken at DFM, before the die is cut
Finish options and where each one belongs
The right finish depends on how the part is touched, cleaned and seen — not on what looks best in a sample photo.
| Finish | Appearance | Best for | Watch out for |
|---|---|---|---|
| 180# bead blast + anodize | Uniform matte, fine texture | Device housings, handles, visible enclosures | Texture must be agreed on a chip; deep scratches show |
| Sand blast + anodize | Coarser, more diffuse matte | Larger panels, industrial enclosures | Can round sharp decorative edges |
| Brushing + anodize | Directional grain, metallic | Audio and appliance face plates | Grain direction must be specified per face |
| Powder coating | Full coverage, wide colour range | Outdoor units, non-cosmetic housings | Adds thickness — mask sealing faces and threads |
| Laser marking | Permanent, high contrast on anodized | Logos, serials, port labels | Must be placed after anodizing; artwork needs vector files |
One colour, one texture, from the first part to the last
This tube is black anodized over a bead-blasted surface. The point of the photograph is not the colour — it is that the tone does not drift from one end to the other, and that the edge break is still visible after the anodic layer went on.
Finish is agreed at drawing review, before the die is cut. If the surface matters more than the tolerance, say so early — it changes the blast, the masking and the order of operations.
How a colour gets approved
Target
You send a physical sample, a RAL/Pantone reference, or both. A photograph is not a target — screens and lighting make it unmeasurable.
Chip
We anodize a chip of the same alloy with the same blast and send it to you. Alloy matters: 6063 and 6061 take colour differently.
Approval
You approve the chip in writing. That chip becomes the reference for every lot, stored with the job record.
Production
Lots are compared against the retained chip under the same light. Anything outside the approved range is held, not shipped.
Honest limits on colour
- Anodized colour varies slightly with alloy, blast texture and section thickness — that is physics, not sloppiness
- Two different alloys on one assembly will not match exactly; specify one alloy across the assembly
- Powder coating covers more evenly than anodizing but changes the surface dimension
- We do not publish a ΔE figure until our own measurement process is agreed with the customer
What we do commit to: the colour you approve on the chip is the colour we compare against, lot after lot.
Finish questions from product teams
The three questions that decide whether a sample is approval-ready.
Can you match our existing anodized colour?
Yes — send a physical sample or a RAL/Pantone target. We anodize a chip in the same alloy and blast, and you approve it before production. See the TWS charging case for how that worked on a two-part housing.
Does bead blasting change the part dimensions?
Bead blast removes no meaningful material and the anodic layer builds on the surface rather than into it. Where a bore or thread must stay to ±0.01 mm, we mask it or cut it after finishing, and we agree that at DFM.
Can you finish parts you did not machine?
We finish the parts we make. Anodizing a part whose blast texture came from another shop means we cannot guarantee the appearance, and appearance is the whole point of the finish.
Send a Sample or a Colour Target. We Will Send a Chip Back.
Tell us the alloy, the texture and the colour reference. You get a physical chip to approve before any production lot is anodized.
What to send
- 2D drawing or 3D model (STEP, IGES, DWG, DXF, PDF)
- Alloy and temper
- Surface finish and color
- Estimated annual quantity