So I've done a few runs and am starting to have problems..

[yoyoboy]

I just recentily started annodizing ( 3 days ago)

The results have been pretty good sofar, but it never reaches par.
Example: I did one of the test bars(completly submersed) total Surface Area-21.375 in.
According to the 720 rule @4.5 amp/sq ft thats .67 amp, 96 min with a par of 11.25V.
My voltage went slowly from 8.9 to 8.6 and the bar dyed nicely.

http://www.flickr.com/photos/yoyoboy/102796525/

Another Example: A yoyo I did total SA of 34.143 sq in @ 6 amp/sq ft and .8 mils
Gives us 1.42 amp, for 96 min and a par of 15 volts.
My voltage looks this:
Time Remaining Volts
1:36 18.3
1:10 18.1
50 17.9~17.8
46 17.5
Then It jumps and stays relatively steady( I wasnt there for thease 10 min)
36 21.8
33 21.5
28 21.5
21 21.2
15 20.9
3 20.5
0 20.4 And I contuied to run the part for another 20 min with the voltage staying the same.
Taking a look at the part You will notice the the unannodized patches. I'm thinking they are caused by insufficient cathodes( 1 GP plate) But why is the voltage so high?
Ignore the crappy masking job http://www.flickr.com/photos/yoyoboy/102796525/
EDIT: maybe you cant see the bare spots.


So, What's causing the high/low voltage? and the bare spots?

[sswee]

Re: So I've done a few runs and am starting to have problems..

Oh man your all messed up, NOT. You only have a couple of minor problems.
1 You misunderstand the readings you are looking at. In electricity you're dealing with 3 main parts. Voltage, current and resistance. Compared to water, the current is the volume needed to do the job. The voltage is the pressure it takes to get that volume to where you need it. The resistance is any restriction to the flow. PAR (peak anodic resistance) is the coatings resistance at it's maximum. The reading for PAR is figured by dividing voltage by current and comes from Ohm's law. The readings you posted are not unusual. As the coating grows, it creates more resistance and has to have more voltage to push the current through the circuit. When the coating cannot grow faster than it is being eaten by the acid, it has reached PAR. When growing the coating and watching the readings it can be misleading. At a point the coating still grows in thickness but the pore size of the coating enlarges from dissolution by the acid. Which lowers resistance allowing the needed voltage to lessen even as thickness increases.

2 I can't view you pics so it's hard to say for sure. The uneven coverage is most likely due to prep. It could be part to close to cathode, not enough cathode.

Tank temp, connections, acid concentration, aluminum content of the electrolyte, SA mis figured can all affect voltage. A difference of +-5V isn't a problem.
SS

[yoyoboy]

Re: So I've done a few runs and am starting to have problems..

UPDATE:
Well actually I didnt want to put it all in one post.
So I did my Ego(paintball gun) And had a lot more problems.

I did half of the parts, because they would not all fit into my tank. Infact I think some of the problems might be caused by over crowding in the tank.

163" .75 mils 4.5amp/sq ft.
gives 5.1 amps for 120 mins with a PAR of 11.25
Time-voltage looks like this:
2:00 5.9
1:42 6.3
1:30 6.3
1:17 6.3
1:04 6.3
43 6.4
34 6.5
15 6.8
10 7.0
6 7.1
0 7.2
I then ran it for 5 more mins and it stayed at 7.2
The body and on/off took dye, but the grip frame , the barrel back, and the other parts didnt.
What they did do is have little speckles of dye on them. I am thinking that thease may have been because of there placement in the tank prevented them form getting areation and the hydrogen bubles built up. Also some of the parts where above the cathode level- (I got lead flashing and now having it running all the way around the sides, but it doesnt go all the way up)
I assume the blotchyness on the body is caused by how it was dyed( I was a bit more concerned with the parts that wernt dying at the time, and wans't verry carfuel while handiling it.
The way I dyed it was on a metal screen with wood runing around the sides.

So whats causing the the Spots? And why did some parts not dye? HELP!

[acidrain]

Re: So I've done a few runs and am starting to have problems..

The voltages are lower with the ego parts because the ego may be made from 7000 series... it will ano at a lower voltage than 6000 series.
As for cathode size, a good rule of thumb is to use is: make it ~equal to the largest run you will be making.
Example: with a 10 amp PS, using 4.5 amps CD = 2.2 sq. ft. of cathode.
Here is a hint: try using 6amps CD for paintball guns. It make a more durable layer, but be careful not to let the tank get over 70F. I ano to .75 mils on everything except black... go for a full 1 mil for that color. Also it is a bit quicker... 90min for .75mil, and 120min for 1mil.
When dyeing, suspend the parts in the dye. Never let the parts touch each other, or the sides of the tank. As you just learned, never handle the raw ano'd parts... always use disposable latex gloves.
Questions:
What is you acid concentration?
What temperature is your tank during ano?
How are you connecting your wires?
What agitation method?

[yoyoboy]

Re: So I've done a few runs and am starting to have problems..

Thanks for all the help!
Sswee- are you saying that I should keep the power on untel the voltage starts to drop? And considering the variables not to worry about the projected time given by the 720 rule?

My acid concentration is 1:3 acid-water
I was running the tank at 75 degrees, I'l make sure to turn it down next time cooling is not a problem in a New England basement.
I'm using alunmium grounding rod spring/press fit into the parts.
As for agatation I think that may be my greatest problem, I'm using the aquarium pump that came with the kit, but i'm not sure I have it set up right. I have one strong jet blasting air.
A note of advice to the rest of you, never strip a Grinder in your main stripper solution, while it may come out looking very nice, your whole house will *smell*

http://static.flickr.com/43/102395211_811d7f8986.jpg?v=0

[sswee]

Re: So I've done a few runs and am starting to have problems..

[quote=yoyoboy]Thanks for all the help!
Sswee- are you saying that I should keep the power on untel the voltage starts to drop? And considering the variables not to worry about the projected time given by the 720 rule?

Not that you should but you can if you want a thicker coating. The 720 rule works. The time and set current in the calculator are good but the peak voltage is just an approximate due to all the variables. As acidrain said the 7000 grade aluminum uses lower voltages. The differences in the aluminum grades has alot to do with their conductivity. I haven't had any trouble since I started using it with the exception of material that was a poor grade to anodize. As long as the voltage climbs, the anodic coating is growing faster than it can be eaten by the acid. The acid eating the anodic coating is called dissolution. Dye only penetrates .7 mil deep, so there are no benefits for dyeing in going thicker. The 11.25V you refer to as PAR is the calculated peak voltage. PAR is the peak anodic resistance measured in ohms. It has to be calculated with the two known variables of voltage and current used on the part. I hope I haven't rambled too much for you.

SS