At my wit' end with wire

[jc88usus]

I have been having wonderful results with everything I have been doing (even made a custom color that was spot-on) EXCEPT with the 18ga. wire. The alloy is the same as the 16ga., according to the supplier, prep is the same, and calcs are the same (even ran both in same batch). The problem is this: the 18ga. turns very dark grey fairly quickly and it starts darkening closest to the elec. connection. I am making coils of wire with 5/32" ID and measuring the length of wire before coiling so I know exactly how much is going into electrolyte. I am coiling loosely so that all sides are exposed. The first few trials (boy have they been trying) I was using 4.5A/sq.ft. and desired thickness of .5mil b|c any thicker just got even darker. I just finished a run attempting only 3A/sq. ft. and it started "burning" after only 45 min. so I stopped the run after 100 min., instead of 120 as Rule of 720 indicated, b|c whole coil was getting pretty dark. It seemed to take the dye well but not a lot of depth of color,DUH, and very "muddy".

Please help, I'm going crazy! I need the wire for an upcoming show and need nice bright colors in the 18ga. to match the 16ga. and 14ga..

[cameraman]

You didn't say what amperage you're setting on your power supply. Based on the 68" length mentioned in your other post, I'm calculating 8.6 in² of surface area, so you should be using .27 amps for 4.5 amps/ft² or .18 amps for 3 amps/ft². Is that where you're at?

[acidrain]

You mentioned "same as 16ga alloy" but you didn't say what that alloy was.
I suspect that they are not the same alloy, but in any case, if the alloy of the 18ga is 2xxx or 7xxx, your ano times will be cut in half.
Try 1 hr at 6A CD for black or other dark colors, and 45min for all other colors.
Make sure you have good agitation, and the tank temp. is 68F to 70F.
Another way to tell if they are the same alloy is to dip both samples in etch, and observe the smut... dark black easily wiped off is 7xxx, and gray black with a blue tint sometimes, not easily wiped off is 2xxx. Very little smut (but a little) is probably 5xxx, and no smut all is 6xxx. Treat 5xxx and 6xxx the same, and 7xxx and 2xxx the same.

[jc88usus]

Originally Posted by cameraman

You didn't say what amperage you're setting on your power supply. Based on the 68" length mentioned in your other post, I'm calculating 8.6 in² of surface area, so you should be using .27 amps for 4.5 amps/ft² or .18 amps for 3 amps/ft². Is that where you're at?

I have 68" @ .048 (according to supplier) which gave me 10.25 sq.in.. this meant that @ 4.5A/sq. ft. I set current at .32A and @ 3A/sq. ft. I ran at .20A.
I am trusting the supplier in their diameter and alloy (5183).

[jc88usus]

Originally Posted by acidrain

You mentioned "same as 16ga alloy" but you didn't say what that alloy was.
I suspect that they are not the same alloy, but in any case, if the alloy of the 18ga is 2xxx or 7xxx, your ano times will be cut in half.
Try 1 hr at 6A CD for black or other dark colors, and 45min for all other colors.
Make sure you have good agitation, and the tank temp. is 68F to 70F.
Another way to tell if they are the same alloy is to dip both samples in etch, and observe the smut... dark black easily wiped off is 7xxx, and gray black with a blue tint sometimes, not easily wiped off is 2xxx. Very little smut (but a little) is probably 5xxx, and no smut all is 6xxx. Treat 5xxx and 6xxx the same, and 7xxx and 2xxx the same.

I am trying to get orange in the 18ga. I got a spectacular orange with the test bar that came in the kit and with the 16ga. that I bought from the same supplier , at the same time, as the problem 18ga.
The temp. is held steady at 70 by frozen water bottles. Isn't 6A awefully high, especially since the wire seems to be "burning" now? I am using an aquarium bubble strip for agitation with the coil hanging right over it. It has been enough for the 16ga....
After stripping, there doesn't seem to be much smut at all on either wires and they come out a beautiful silvery grey.

[cameraman]

.048 is closer to 16 ga, at least by the table I'm looking at:
16 = .0508
17 = .0453
18 = .0403
but that should be close enough anyway - main thing was to make sure you weren't putting a couple amps through it.

Using the higher current density will result in smaller pores, which may lighten the color a bit, but requires more aggressive agitation (not necessarily more than you're providing, just more than lower CD).