First attempt at home anodizing

[Walltoddj]

Ok took a shot in the dark today and tried to Anodize a piece of aluminum. First I got no bubbling in the lye cleaner I used Draino so we are going to try to find straight lye. Put it in the Sodium Bisulfate acid bath and did see small bubbles for two hours as the 720 calculated at 15v 1.1amp on my DC power supply. The part came out with a little yellow tint as I had read in one of the articles so I rinsed it and put it in the dye. It was in the dye for about a 1/2 an hour but did not take on any color after rinsing again the part has a nice matte finish but no color. We will have to see maybe tomorrow I'll try it again if I have time.

Todd

 

[darkzero]

Nice, I've always wanted to try anodizing alum but didn't want to mess with it at home. My buddy has sulfuric acid that I can use. Recently I needed a bunch of handles anodized clear so I thought about trying but I ended up just taking it to a local anodizer. I can only anodize titanium but that's easy.

 

[Walltoddj]

Still trying to get the part to take the dye but no luck. Did find one thing by accident I hardened the aluminum which is the main idea I had in mind. I use battery acid in the bath with a lead plate instead of aluminum at about 24v 1.2 amp. I'm going to try to repeat this again to see if I can do it that way every time and then get it to take the dye.

Todd

 

[Walltoddj]

Ok after a couple of tries I found that acid is the key to case hardening Aluminum tubes. I still can't get it to take the dye anybody got any ideas? Now I'll try acid with the aluminum cathode instead of lead to see what happens though they say the cathode never wears and I've got a 12"x 12" sheet I'm using it should last a while. I'm at 5 amps 24 volts for 2 hours which is in line with the 720 rule.

Todd

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[Alan Douglas]

I recall reading that some Rit dyes contain salt.

 

[darkzero]

I recall reading that some Rit dyes contain salt.

Funny you should mention Rit, I just bought a bottle a couple of days ago but I'm dying plastic. Yes, the bottle does say it contains salt. I know nothing about anodizing aluminum, only titanium, is salt bad & is Rit one of the dyes people use for anodizing aluminum?

 

[JoeSixPack74]

I have seen many people on the web use Rit dye and most of them have mixed results. A 4oz package of dye made for anodizing from Caswell Plating is around $15. After all the time you take to machine a part and polish it why go cheap on the dye?

 

[Alan Douglas]

Aluminum corrodes in salt water, even anodized aluminum unless it's hardcoated.

 

[Walltoddj]

Well after reading a couple of other sites the information point to the fact I stumbled on type III anodizing which is a harder surface but does not take dye. I'm going to try to make two anodizing bathes so I can try to get it to take the dye, what I'm reading is with the battery acid it needs a 50/50 dilution for type II. I think at this time I'm at a 10/1 dilution which is one of the reasons they say it is for type III. I still don't understand why the sodium bath does not work because it's still soft when hit with a file. Oh and just so you know that is my hardness test if the file cuts it it's soft, when the file slides it's hard and by that it that's a lot of pressure to cut though the anodize coating.

Todd

I can't find Rit dyes but on the dyes I've gotten you add salt or vinegar to it depending on the fabric your dying it contains no salt.

 

[Walltoddj]

I finally got what I wanted a file hard dye able part. I found the problem is the dye, I got some Rit dry that did what I wanted a nice Gold color. By using battery acid at 16 quarts of water( I used tap water they say use distilled) to 1 quart of acid, a lead cathode, at 5 amps 19-20 volts for 120 mins. the part is a tube 1 1/2" OD x 9" long which comes out to about 85 sq inches of surface (it's anodizing both the inside and the outside). The dye has no salt I've shown a photo of the box you add salt or vinegar for cloth, I mixed it 2 quarts distilled water to 1 packet of dye I might be able to add more water but it did work this time. You can see if you look at the fifth line it said add salt or vinegar to the dye and the bare spot on the part is where I filed though the anodize.

Todd

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