Finishing the Top Plate Chemically

[karl]

I would like to finish the aluminum top plate in a fashion similar to blueing steel. I know that such processes exist, but I can't remember what they are called.

Any help on processes and products for accomplishing this would be appreciated.

Regards,

Karl

[Doc B.]

There is anodizing, and there is some stuff by Birchwood Casey (the guys who make the most commonly available cold blue for steel) called aluminum black. Anodizing is very effective, a zillion colors are available, it requires an electrode and it is probably a bit expensive to have one panel anodized. The aluminum black comes off the shelf in a bottle and can be easily applied by wiping. In my experience it is useless, basically just turns aluminum a dirty gray.

I heartily suggest that anyone interested in DIY metal finishes check out the Caswell Plating website

http://www.caswellplating.com/kits/index.html

[karl]

Doc -

Thanks for the suggestion. I am looking for the process that will turn aluminum to a dark plum color. Anodizing would be very cool, but I can't justify it right now.

Regards,

Karl

[Doc B.]

As far as I know plummy aluminum is usually an old black anodized finish that has "gone plummy".

[tdogzthmn]

I have a similar question about finishing the top plate.  I wanted to get the nice matte look that you find on most apple computers.  I don not think it brushed aluminum since it does not have a grain.  Would this be done by sand blasting or can I achieve this matte look by hand sanding. 

Thanks in advance.   

[ironbut]

Good question. I really like the finish on Apple products too.
I don't think you could ever get rid of the scratches that sandpaper makes. I would imagine that their finish is anodized but I could be wrong.
Maybe I'll try and scratch off some of the finish on the inside of my Mac Pro tonight and have a look see.

[Doc B.]

Matte finish on alu is usually done by bead blasting, then anodizing. The existing grain would make that tough to do without polishing the plate first. You might blast it with sand instead, which would make a lot heavier texture. This is a pic of a Seduction whose plate I taped off except for some narrow bands, that were then sandblasted to match the finish on the Ampex 934 tape deck next to it.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.bottlehead.com%2Floosep%2F960andpreamp.jpg&hash=717ecd0c741900dccfe5b7da985d2b4891549c1e)

[tdogzthmn]

Matte finish on alu is usually done by bead blasting, then anodizing. The existing grain would make that tough to do without polishing the plate first. You might blast it with sand instead, which would make a lot heavier texture. This is a pic of a Seduction whose plate I taped off except for some narrow bands, that were then sandblasted to match the finish on the Ampex 934 tape deck next to it.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.bottlehead.com%2Floosep%2F960andpreamp.jpg&hash=717ecd0c741900dccfe5b7da985d2b4891549c1e)

I was talking to someone in the shop that mentioned using walnut shells, or glass beads to get that mac-like finish.  Either way I will probably seek professional help.  For the base I am planning to ebonize the wood.  I am going for minimalist look, clean and simple.  Thanks for providing the lovely example of your work!

[syncro]

A tumbler will produce a nice matte finish, but finding one large enough for a plate would be tough.  Metal fabrication industries have them to finish and polish parts.   I tumbled the much smaller bell housing of the FP3 transformer, which is steel, in an ultra-sonic tumbler primarily used for rocks and minerals.

Anodizing can be done multiple times, combining different colors and darkening with each, to achieve unusual coloring.   Take a look at http://www.linetec.com/ANODIZE/EcoFriendly_Anodize.html  The etching may be all you need to have done for interior application.  You might research what acids are used and/or experiment to achieve a look.  I would not expect to be able to get a consistent/smooth surface like a mac product.