Guides / Finishing
Finishing Audio Parts: Anodize, Brush and Blast
A faceplate is judged on its surface before anyone reads a spec sheet. This section is about controlling that surface, and about the fact that most of it is decided long before the part reaches the anodizing tank.
Generic machining blogs cover anodizing as a list of colours. That is not the problem a hi-fi brand has. The problem is that the panel and the sleeve came out different shades of black, that batch two does not match batch one, and that nobody can say why.
The answers are almost always upstream of the finisher: alloy, mill lot, surface preparation, rack position and dye lot. This section works through each of them, with the drawing language that turns an appearance into something a supplier can quote and repeat.
What this section answers
- Why 6061, 6063 and 5052 anodize to visibly different colours, and what to do about it
- How to write an anodize specification a finisher can repeat next year
- Brushed grain: grit, direction and continuity across two parts
- Bead blast media and grit, and why blasting is the best tool for matching mixed alloys
- Marking a panel: engraving, laser, silkscreen or pad print
- Brass and copper, and how to stop them turning brown on the shelf
- What low volume anodizing costs and six ways to bring it down
- Where a surface roughness number helps, and where it misleads
8 guides in this section
In reading order. Each one stands alone, but they are written to be read in sequence.
- Finishing
Sep 2, 2026Which Aluminum Alloy to Use for an Anodized Audio Part
6061, 6063, 6060 and 5052 all anodize differently. What each one does to colour, clarity and machining, and why mixing two alloys in one product causes trouble.
- Finishing
Sep 20, 2026Anodize Colour Matching Across a Batch and Across a Year
Why the faceplate and the knob come back different shades of black, what controls anodize colour, and how to write a spec a finisher can repeat next year.
- Finishing
Aug 28, 2026How to Specify a Brushed Finish on an Audio Front Panel
Grit number, grain direction, dry versus wet brushing and why the grain has to continue across two parts. The callouts that make a brushed panel repeatable.
- Finishing
Aug 24, 2026Bead Blasting Before Anodize: What It Fixes and What It Hides
Glass bead, aluminum oxide and grit size all change how an enclosure looks after anodize. How to specify a blast finish so batch two matches batch one.
- Finishing
Aug 20, 2026Marking a Front Panel: Engraving, Laser, Silkscreen or Pad Print
Five ways to put a logo and channel labels on a front panel, what each costs, how each survives ten years of use and when in the process each one happens.
- Finishing
Aug 16, 2026Making Brass and Copper Audio Parts That Do Not Turn Brown
Brass knobs, copper trim and bronze feet look superb and tarnish fast. Alloys, lacquers, plating and the drawing notes that stop a batch ageing on the shelf.
- Cost
Aug 12, 2026Getting 30 Parts Anodized Without Paying for 300
Anodizers price by rack and by tank time, not by piece. What that means for a boutique audio run and six practical ways to keep a small batch affordable.
- Finishing
Sep 16, 2026Ra, Rz and Why Neither Describes How a Panel Looks
Surface roughness numbers are useful on a sealing face and misleading on a cosmetic one. What Ra measures, what it misses and what to specify instead.
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Other sections
Chassis
An enclosure is three or four parts made by different processes that have to end up looking like one object. This section covers how each part is made, what it costs and where those two things fight each other.
Parts
These are the parts people pick up, turn and look at closely. They are small, which makes every cosmetic requirement harder, and they almost always come in matched sets.
Sourcing
Machining a front panel is not difficult. Making the same front panel again in a year, to the same appearance, is the whole job. This section is about buying that rather than buying a price.
For shops
The other half of this business. These are written for the shop owner rather than the buyer, because a match only works when both sides understand what the job actually costs.