Turning alum. black

[flailing]

Anyone know what chemical I can use to turn alum. black?

[JoeR]

Don't want to be a smarta$$ but paint works good for me... Actually if there is a way to anodize it black at home...

[Mr.RC-CAM]

Here is a source for some plating stuff and info: http://www.caswellplating.com/

[Quacker]

Other than paint (you must prep aluminum in order for paint to stick), you might look into anodization. This is the most common way to apply black or other colors. You didn't tell us how much aluminum, so seeking a local anodizing shop (there are lots of them under anodizing/plating) may not be practical if it's a small order. On the other hand, some platers might be friendly and do small requests for free. You might also search the web for a "how to" for anodizing. This is not a magic process and with a little effort you just might get it to work at home.

Q

[flailing]

Anodize would be best but I don't think a shop will do it at a price I can justify. I really don't want to use paint the parts are very small with tiny little holes in them. I was thinking of a chemical soak kind of like the patina kits sold at craft stores I am going to look for one tomarrow that works on alum. The parts are the rigging fittings for my Hansa Brandenberg G1.

[Mr.RC-CAM]

The web link posted above has details to a $175 alum anodizing kit that might do the trick. That is about what you will pay at some plating shops for a couple of small jobs. If your needs are ongoing then the investment may be worthwhile.

http://www.caswellplating.com/frames.php?bottom=/aluminum.htm

Here is a link with photos to model parts plated with the kit:
http://www.caswellplating.com/frames.php?bottom=/other_projs.htm

[deadduck]

Anodizing would be best.

There are gun blue touch up pastes and pens but you would have to check if they work with aluminium.

[gcampbel]

The product you want is Birchwood Casey Aluminum Black Metal Touch Up. It is a gunsmithing product. It is very cheap, comes in a 3oz bottle. You can usually find it any where they sell gun cleaning products and almost every sports or gunshop has it. You have to make sure your part is abslolutly clean and oil free. Steel wool the part (fine) then apply with a cotton swab or dip. let stand for a minute or so and rinse with water and there it is, black. after it's dry you may polish off some oxidiation powder with a cloth. If the black is not deep enough, just do it again.

Glenn

[Red Baron 47]

flailing,

I've had very limited success with gun bluing. It occasionally turns some types of Al black. I have better luck with a magic marker. The ink is very thin and might do the trick. I frequently flick them in a safe place with the cap firmly on like you would a body temp thermometer to get the Mercury down if you're old enough to have done such a thing. You can then use a tiny brush in the ink collected in the cap.

I just tried both Brownell's Dichropan and Birchwood Casey Perma Blue cold bluing solutions on a piece of K&S Al tubing after wiping it with acetone. It didn't touch it. I also put on some Easy Off spray oven cleaner. It etched it. I then put on one of the bluings and it still didn't do anything.

I've posted a picture of Aluminum Black. They say it works. I vaguely remember having tried it in the past with mixed results, but I can't find it. The bottom line is that in my experience of trying to turn Al black over 30 years experience is that it's hit or miss.

Hi Glenn,
I see you posted while I was doing tests and looking for things. I'm glad to hear the BC Al Black works.

Sorry I can't think of anything else.
Good Luck!
RB

[gcampbel]

I must stress that when using Any cold metal blackening chemical, the metal must be absolutly clean of any oils including finger prints. Use the strongest degreaser you can find or you will have an uneven finish.

I also use a black baking lacquer. You air brush a primer on, then the Black Lacquer and bake in oven at 200. Real black and real hard finish. availiable from http://www.brownells.com/

Glenn.

[Red Baron 47]

I found my BC Al Black. It's probably 20 years old but it works like a champ on K&S tubing.

Glen, I doubt that flailing will be able to steel wool his tiny parts so I just wiped a piece of 1/8" tubing with acetone and dipped it in. It's a rather vigorous bubbling reaction. It turned black very quickly, maybe 20 seconds. I then wiped strongly with a paper towel and most of it came off. I dipped it in again and ran it under cold water before wiping and most of it stayed on.

One problem flailing might run into is that when it comes out of the solution the black is very rough and lumpy. Wiping with a towel cures this, but might be difficult with tiny parts. Diluting the solution might alleviate this.

Here's a pic.

[flailing]

Thanks guys I will try the Alum black we have plenty of gun shops this is Texas after all.

[Stregone]

I read an article on how to anodize aluminum a while ago, but the site its on seems to be down right now. It was pretty simple, you just needed some rather nasty chemicals.

[flailing]

Kind of like photo etching some nasty stuff there but the results are great.

[Stregone]

Here (http://www.maxxtraxx.com/tech/tech006.shtml) it is. I dunno why I couldn't get to the site earlyer. Have fun!

[Red Baron 47]

Hi flailing,

Something I was thinking about later. The stuff gives off what smells like Hydrogen sulfide. It's meant to wipe on small nicks in Al pieces. If you dump in a handfull of small fittings, you may get quite a stink.

Also be sure to do plenty of tests. As I said, you get a loose flocculated layer at first. After the cold water rinse and wipe, it lays down and sticks, but it might clog your tiny holes. Dilution with pure water may be the key.

[Kevin Murray]

Here is another at home anodizing link.

http://www.focuser.com/atm/anodize/anodize.html

[ghoti]

I black anodized aluminum parts in my garage a few years back.

1) clean Al in solvent
2) etch (for ultimate cleaning) in NaOH solution until frosted all over
3) rinse in water
4) dip in battery acid (H2SO4) and pass DC current through the part to a second aluminum electrode in the bath. About 2-4 amps from about 20 volt source (if my memory serves me... forgot what polarity was which) This might take 30 minutes or thereabouts. Use a ceramic crock for this.
5) remove and rinse in water It is now anodized but clear.
6) dip into boiling solution of black rit dye. (Better dyes are available i forget the source) The dye enters the pores and boiling seals them. I think I started cold and brought it to a boil with parts immersed.
7) rinse and dry

after step 2, don't touch metal surface with anything.

I hung the parts using Al house wire (romex) stripped.
If lots are parts are to be processed watch acid solution temperature, it will ramp up.

I hated it for the toxic waste left over and the hazardd of aggressive chemistry. Get someone else to do it for you.

Bill