How to finish aluminum?

[jason_n]

Don't know if this is the best forum, but I'll give it a shot.

I've got some small aluminum pieces that I need to make look nice. My plan was sand to 600 then spray with shellac. Well I got to 600 and now they are smooth but dirty. What can I use to clean them before I spray?

I appreciate the help.
Jason

[Regnar]

At work we always used NeverDull or Mothers Chrome and Mag Polish.

[schiada96]

409 and hot water

[Anodizer]

In my shop at work, before anodizing, I use Simple Green to remove all fluids and polishing compounds.
If the item needs polishing, I use a Dremel tool, buff wheels and Flitz metal polish.
You probably do not have access to one, but a small vibratory tumbler for brass shell polishing does a great job. Start with treated walnut hulls, then go to the corn cob for a near mirror finish. You can get these items at Midway, a supplier for firearm reloading, etc. You just cannot put too large of an piece in this size.

Fred
The Anodizer

[WoodSnarfer]

Originally Posted by jason_n Don't know if this is the best forum, but I'll give it a shot. I've got some small aluminum pieces that I need to make look nice. My plan was sand to 600 then spray with shellac. Well I got to 600 and now they are smooth but dirty. What can I use to clean them before I spray? I appreciate the help. Jason

Does shellac on aluminum come out okay? Does it adhere well with no crazing due to material (thermal) differences)? Maybe a very thin film buildup is the trick (?)

-Chris

[Anodizer]

Chris,
I would not use shellac, rather a polyurethane like Minwax spray polyurethane. This is what I use in my shop and it appears to be pretty durable. It does require a slightly rough surface to bond.

[jason_n]

Thanks for the ideas everybody.

Fred, does the spray poly dry yellow like it does for wood?

I'm going off something I read a couple of years ago, and I thought they recommended shellac. Maybe my new question should be:

How does one do a DIY finish on aluminum. Dull is preferable (is that brushed aluminum?), but shiny is OK. I just want something to keep from turning my fingers black and leaving prints all over the aluminum (the way raw aluminum does). Who knows an easy way?

Thanks again,
Jason

[Anodizer]

Shellac is made from an insect, a beetle I think, and yellows over time and is brittle. The Minwax looks clear with no perceivable coloring. You can get it in gloss or satin. So far, I have not seen any deterioration in the finish on the boxes I coated. You could also try Krylon clear.
I make a satin finish by using a very fine grad of Scotchbrite. If I need a matte finish, either glass bead blast or vibratory tumble with plastic media.
I mostly anodize the items I make as this is about the hardest surface you can put on aluminum. It is not that hard to do and you can get a kit from Casewell Plating to do it. Check out their web site.
I have been thinking about setting up an anodizing workshop at home to take in work. But, I need an area I can keep people out as the anodize bath is sulfuric acid diluted, but will still give a serious burn.

[SORCHEROR]

how many are you making?i send mine out for clear irridite,or comonly known as clear anodizing,would cost to much for just one,but many wouldnt be bad,they all have a certain minimun lot charge,best way to keep aluminum clean and gives a harder surface,just a thought
steve

[Anodizer]

Anodizing and irriditing are two different processes. anodizing is a chemically produced oxide coating to the aluminum surface, giving it the hardness of sapphire. Irriditing, or alodising, is a chromate conversion coating to a clean aluminum surface, giving it a gold or green transparent color. Alodising prevents corrosion and gives a good bond for painting. It has no strength and can be worn off.
There are two steps to alodising, a caustic cleaner to remove any deposits and surface aluminum oxide and the actual alodise bath. Henkle makes these chemicals and they can be bought through aircraft maintenance suppliers.
This process is being discontinued as chromate is a severe carcinogen.
My anodizing process is seven steps, I do the whole schmear. a single piece takes about 2.5 hours.
I have been doing both processes for about six years. I am getting away from alodising because of the cancer risk and the alodise chemical has a shelf life of one year.
If there is sufficient interest, I might go ahead and start a cottage anodizing setup as home units are too small for the EPA to care. I still dispose of used chemicals in an approved manner.

[martinw]

I stumbled on this site a few weeks ago that shows some DIY anodising.

http://astro.neutral.org/anodise.shtml

I have not tried using the method described, but it looks pretty straight-forward.

Best wishes

Martin

[Anodizer]

Just be careful. The actual anodizing treatment bath produces hydrogen and hydrogen sulfide gases. One, very explosive, the other toxic.