Anodizing Multiple Pieces

[DeanP]

I'm fairly new at this and had question about anodizing multiple pieces. How important is it that every thing in the run is close to the same size(surface area)?

I made a run today with three pieces that were 16, 46 and 69 sq in. (131 total). I ran at 6 a/sf (5.5 amps) for 108 minutes shooting for 0.9 thickness. It appears that the smallest piece turned out the best (It seemed to take the black dye better).

Thanks for your help.
Dean

[acidrain]

They will all anodize the same if they are all the same alloy.
You could have lost connection too.

[Ready2Dye]

I was wondering the same thing


thnx acid.

[M_D]

The larger parts do tend to have connections go bad because of the higher current flow, and also larger parts need a heavier wire to carry more current. So, even if the connection didn't go bad, a wire too small will cause too much resistance, in effect making the actual current density higher on smaller parts and lower on larger parts.

[Ready2Dye]

Ok so I ran these 2pcs (smaller is 36"sq and larger is 63"sq) @ CD 6asf with a cc of 4.1A it started at 14.9V and held then jumped up to 21V I shut off agitation and examined connections, restarted agg and and all of a sudden it was @ 14.6V this happened a couple times through the run.

Was shooting for .7mil and ran for around 80-90min.

I dyed the part in gray bl for 5min at 140deg. and sealed for just over a half-hour

so my ? is what happened when the V's went up many times to like 20-22V (other than bad connection) did it ruin or distort the growth (disolution?) did it grow more on one than the other?

I forgot to take a pic when they came out of the ano bath but the smaller one was very dark and yellow and the larger part was a beautiful clear ano shade. After sealing in boiling Nickel bath for over a half-hour the small part's dye rubbed all over the place but the larger one sealed fine.

why did the larger one come out good and the little one like poop?

nice picture utility site: Shrink Pictures.com

[kco1196]

If you don't mind me jumping in here my guess is the smaller part didn't have a good connection. Otherwise, the dye wouldn't rub off.

So far I have ran about 5 batches of parts. Something important I learned is this: When hanging parts with aluminum wire hold the part up by the end of the wire that will connect to the bus bar. Next, wiggle the wire and see if the part remains 'fixed' or if it moves. If the part moves when I shake the wire the connection isn't good enough (for me). Ever since I have checked my connections using that method they have come out 100%.

[Ready2Dye]

If you don't mind me jumping in here my guess is the smaller part didn't have a good connection. Otherwise, the dye wouldn't rub off.

Don't mind at all; infact I apprectiate any input to this problem- Thank you!

What's funny is the connection on the smaller part was more solid than the larger one. The smaller part has a larger dia. hole that lets me get a much more tighter loop than the small dia. on the big part (that one just "flops around).

No more of this twisting wire BS! ( I have just ordered .5 inch titanium screws for like a $1.50 a pc from Chris @ Tico Titanium )

What gets me is that I thought the larger one had not ano'd and the smaller one was REALLY ano'd to the max by looking @ them when they came out of the ano bath.

Also I took a rag AND my thumb and wiped off ALL the coating/dye I could and THEN took the pics. SOOOO......

Why is there dye in someplaces and not others? If it lost connection wouldn't ALL the dye come off?

[Ready2Dye]

What gets me is that I thought the larger one had not ano'd and the smaller one was REALLY ano'd to the max by looking @ them when they came out of the ano bath.

Also I took a rag AND my thumb and wiped off ALL the coating/dye I could and THEN took the pics. SOOOO......

Why is there dye in someplaces and not others? If it lost connection wouldn't ALL the dye come off?

(Light bulb goes off)
Just a thought here: If I DID infact coat the small part WAY MORE than the big one, did I not seal long enough?
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[kco1196]

Looking back on what you've said...

clue #1
"when they came out of the ano bath but the smaller one was very dark and yellow and the larger part was a beautiful clear ano shade"

One evidently anodized proper, which one?

clue#2
"Why is there dye in someplaces and not others?"

Surface preparation-
How did you prep each part? Did you try the water break test on both? Could there have been something oily on the smaller part.

Seal temp? How warm was the bath? 160-200'?

Honestly I cannot answer these questions for you because I don't have enough experience but I wanted to share those thoughts with you.

[sswee]

Are both parts the same grade of material?
The yellow or golden color usually indicates a heavier coating.
The hazing or color wiping off usually indicates dissolution.
It looks like part prep and connection problem.
I didn't see what your tank temp was for the run.
SS