color issues

[jc88usus]

I have only run 6 or 7 runs so far. The batch with green dye came out beautifully, but the orange is more of a copper color rather than a nice bright orange. All prepping and onodizing were consistent within runs. I ran the green pieces first and then the orange. I did notice that the aluminum is darkened by the anodizing process in the last couple of runs and this seemed to affect the color. The color was a very greyed orange even after only a few seconds in the dye. All temps and rinsing are per the LCD manual. Please help, I am trying to create "U.T. orange".

[destroyer125]

are your parts bead blasted /peened? overblasting your part can cause them to get dark greyish spots in the coating

[sage]

The final color is pretty dependant on almost everything in the process. If your aluminum is turning quite dark during anodizing and it was bright and shiny before, it might be that you are anodizing too much. If you keep the time and current down to get you 0.7mils, at least with 6061 alloy the color shouldn't change too much. 0.7 mils is all you need to get good color. Also the color shade will change the longer you dye. If you haven't done so you should only dye in until you see the color you want. Depending on the process parameters you might only need to dye for a 30 seconds or so.
You might want to quote some of your process details so we can suggest a solution to your problem.
Please include time,temp sq/in and all details you went though in every step.

Sage

[jc88usus]

Current and time were set to get .5, 1.0, and .75 mils in separate runs and the dye color did not change that much with more or less time, it just got deeper.
The parameters were as follows:
Material: 18 gauge (.048" diameter) aluminum wire (sold as alloy 5154-H1 spooled to different inside diameters with different lengths. The lengths were measured before spooling so that Amperage could be calculated using dia.*length to be anodized*pi = sq. in.; then sq. in. * .03125 = Amps.
Preparation: Spools were put in stripper briefly until nice pale grey, almost white and passed water break test. They were rinsed thoroughly with distilled water, put in de-smutter/de-greaser at correct temp. for about 3 - 5 min. and rinsed again.
Anodize: Electrolyte is a 1:3 ratio of battery acid and distilled water held between 68 and 70 degrees with ice (frozen bottles of water). Work piece is held over aeration strip in center of tank about 3" from each gp plate. Electical connections are using 14 gauge electrical wire and alligator clips. Constant current source is turned on with current set as determined using above calculations. The color change in the metal from pale grey to dark grey was almost immediate ( in 10 minutes or less). Anodize time varied according to thickness of layer being tested. Thorough rinse afterward prior to dying.
Dye: Dye was prepared according to directions and a test strip (provided in kit) was treated initially with great results, a nice vivid orange. Dye was brought to approximately 140 degrees prior to use and time in dye varied from just a quick dip to the full 15 minutes. The dark grey of the metal made for a "muddy" orange that only intensified with longer dye time. The piece was then rinsed and sealed.
Sealing: The sealant is the one included in the kit and prepared according to instructions and brought to a full boil before and during the sealing process. The piece was left to seal for 15 minutes and then rinsed for a last time and hung to dry.
What is very curious to me is that the test bar came out spectacularly as did some 16 gauge from the same dealer. Could it be the diameter of the 18 gauge wire is just too small, or just the alloy is not as advertized? I am beginning to get fairly frustrated.
I hope this is enough info to be of some help, if not I will send any details you need. Thanks.

[ken_the_stp]

hmmm.
If all your calculations are correct and they are the same alloy there is one factor that i think may be the culprit. The thiner wire will heat up more than the thicker wire. The extra heat may have lead to dissolution. To test this you could connect more than one end of the wire to the power. Or you could use several pieces of TI wire an hook it to evenly spaced parts of the AL wire. This would shorten the path the current has to travel and prevent the wire from getting too hot.

[cameraman]

I think the 18 ga wire is probably carrying the current ok, although it certainly wouldn't hurt anything to connect both ends to the anode.

You don't have to use the stripper unless there's a coating that needs to be removed. I would suggest trying a run that's been desmutted but not stripped, and I wouldn't desmut for very long - maybe a minute and a half max.

I believe the flats which come in the kit are 6061. I had some unknown alloy that I'd gotten at a hardware store that turned very dark with black streaks when anodized; I suspect that your darkness is due to the alloy - you might try some different wire. I got some at the hardware store that is again unknown alloy. It's sold for 'sculpting, hobbies, crafts', in a little plastic dispenser package. I'd gotten it for use as connection wire but it comes out a really beautiful blue.

Something else to try, and this is just total guesswork but is something I'd try next, would be to hit it with 6-10 amps/ft² to a thickness of .5 mil with really aggressive agitation. .7 is generally better for dying but with the orange you may be better off with .5. I've also noticed that it doesn't take much immersion time with the orange. It sounds like you're already doing it, but like sage suggested, you may want to pull the piece after only a few seconds to inspect the tint.

The ice bottles are positively brilliant; I can't believe I didn't think of that - I regularly do that on camping trips but it never occurred to me for the ano tank.

[sage]

Seems like you have all the details covered. I wasn't quite understanding how you are anodizing a spool of wire though. Obviously couldn't still be on the spool.

As mentioned, the alloy is most likely the culprit. I can't speak for the alloy you have. I'd have to look it up. I think High silicon is a no-no (Or maybe it's copper??)
Is this MIG welding wire - assumed because it's on a spool? I do a lot of TIG welding (same wire) and Lincoln recommends 5356 as the only welding wire alloy that will anodize well. I can vouch for that. I've used it.
Maybe you can get some 5356 #18 MIG wire on a spool. That's pretty big for welding wire but it probably exists.
If you want to try it go to the welding supply and get a couple of sticks of 5356 TIG rod - same thing - and you should be able to buy it a rod at a time.
I've used it and it to weld 6061 and it anodizes and dyes almost exactly the same.

Sage