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geekhack Projects => Making Stuff Together! => Topic started by: Photoelectric on Fri, 03 February 2017, 09:02:59

Title: Sandblasting aluminum for a semi-gloss finish?
Post by: Photoelectric on Fri, 03 February 2017, 09:02:59
I'm a little confused what the preparation process is for a semi-gloss finish of anodized aluminum.  For example, GON used to offer his keyboards in "no glare", "semi-glare", and "glare" options--all were textured, sand-blasted type, but I think the size of grain different, from fine grain being matte to large grain being shiny.  I know a number of custom keyboard makers routinely offer this finish, such as LifeZ, Duck (especially), FMJ, some others.  I've asked one of them about the process and was told "sandblasting" + "bright anodizing".  So bright anodizing, as done in the U.S. shops I've called, basically is done on more satin type finishes, smoother ones, and I thought that doesn't really add gloss on its own.  Just makes a part lighter prior to anodizing, unless I misunderstood.  It's the underlying texture that can be glossy or matte, and anodizing itself (that is converting top layer to an oxide) actually slightly dulls a surface anyway. 

So I called a local shop that does metal finishing, including sand- and bead-blasting, and the guy told me he'd never heard of a glossy finish after sand or bead blasting--that it's usually more on the matte side.  That it does have some sheen on it, but not much.  I don't know if he means that it's simply not as glossy as a high polish aluminum surface, but what I'm looking for is Duck keyboard-level of gloss, like this:
(http://i.imgur.com/yn6CCwQl.jpg)

Not matte like this (outer case):
(http://i.imgur.com/rT4QrVyl.jpg)

If anyone could give me some tips on what to request when speaking with a finishing shop, that'd be great.
Title: Re: Sandblasting aluminum for a semi-gloss finish?
Post by: OverKill on Fri, 03 February 2017, 17:52:43
The top picture is zinc plated and the bottom picture looks like it was anodized.
Title: Re: Sandblasting aluminum for a semi-gloss finish?
Post by: Photoelectric on Fri, 03 February 2017, 19:49:14
They are both anodized, not plated with anything.

I've figured it out.  Bright dip anodizing is the key, it adds the extra gloss by smoothing out the finish in a certain way.