Guides / Finishing
Anodising and E-Coating Compared for Case Makers
September 21, 2026
Most keyboard cases are anodised. When they are not, the reason is almost always colour, and the alternative is almost always e-coating. Knowing which one your design needs before you send the drawing out saves a prototype round.
What each process actually does
Anodising converts the surface of the aluminium into a porous oxide layer, pulls dye into the pores and seals them. Nothing sits on top of the metal. The colour is inside the metal’s own oxide, which is why it survives abrasion so well and why the alloy underneath influences the final shade.
Electrophoretic coating, usually called e-coating or electrophoresis, deposits a resin film onto the part electrically and then cures it. It is a coating in the ordinary sense: an opaque layer on the surface.
That structural difference drives every practical trade-off below.
Colour range
This is the reason anybody chooses e-coating.
Anodising is translucent. The aluminium shows through and the alloy tints the result, so an anodised white is always a very light grey and an anodised pastel always has metal underneath it. Deep saturated blacks are possible but tend towards a dark charcoal with a visible metallic quality.
E-coating is opaque. True whites, clean pastels and flat dense blacks are all straightforward. If your colourway is the selling point of the board and the colour is not achievable in a dye bath, this is your answer.
Surface defects
Anodising is transparent to whatever is underneath, so every machining mark, blast inconsistency and handling scratch shows. The scrap rate on a fine blasted anodised case reflects that.
E-coating covers. Not everything, and not a deep gouge, but a film hides minor surface variation that would scrap an anodised part. On some designs that meaningfully lowers the cosmetic scrap rate.
Thickness and fits
Type II anodising adds a small amount per surface. E-coating adds noticeably more.
In a pocket, both walls get coated, so the pocket shrinks by twice the build. A plate pocket drawn as a precise fit and then e-coated may simply not accept the plate. This is one of the most common reasons a case that measures correctly fails assembly, and it is why the drawing needs a line saying whether dimensions apply before or after finishing. More on that in which tolerances actually matter.
Durability
Anodising wins on abrasion, particularly at edges and corners where a coating is thinnest and a converted oxide is not. A board that gets moved around a lot will show wear on an e-coated edge before it shows wear on an anodised one.
E-coating wins on chemical resistance and on uniformity across a complex shape. Both are fine for a keyboard that lives on a desk.
Cost and availability
Both are batch processes with similar economics. Anodising is more widely available, and almost every machine shop that does cosmetic aluminium has an anodiser it works with. E-coating is a smaller field, so it is more often a separate vendor with its own queue.
That makes e-coating more of a scheduling question than a cost question. Ask specifically who does it and what their lead time is, because it is a link in your chain you cannot see.
Mixing the two on one board
It happens: an anodised case with an e-coated accent, or e-coated halves with an anodised weight. It looks good and it is legitimate.
Understand what you are buying. Two processes means two vendors, two queues and two chances to slip, and the two finishes will never be quite the same texture even in nominally the same colour. If the parts sit side by side, get a sample of both together before you commit.
The decision, in one line
If your colour is achievable in a dye bath, anodise. If it is not, e-coat and design the extra thickness into your fits from the beginning.
Everything else is secondary. And whichever you pick, agree the colour against a physical sample rather than a render, because that failure mode is identical in both processes.
Frequently asked questions
Why do some colours need e-coating?
Anodising dyes sit inside a translucent oxide layer, so the metal underneath always shows through. That makes deep flat whites, true pastels and some very dense blacks effectively unreachable. E-coating deposits an opaque film, so those colours become available.
Is e-coating less durable than anodising?
It is a film on the surface rather than a converted layer of the metal, so it can chip at a sharp edge where anodising would wear. In normal desk use both last for years, but anodising handles abrasion on corners better.
Does e-coating affect my tolerances?
Yes, noticeably. It builds more thickness than Type II anodising and it goes on both walls of a pocket. A plate pocket designed as a precise fit can close up enough to stop the plate going in. Design the allowance in from the start.
Need a quote for your case?
Send the files. We match you with up to 3 shops that machine keyboard cases and reply within 24 business hours.
Get matched with a keyboard case shop