Disolved Al in Ano tank and Ano thickness?

[ron83]

OK,
I am having a problem with my anodizing layer not being as thick as I think it should be and not sure what causes that. I am following the LCD method and only anodizing freshly milled 6061.

Checked all simply things:
Parts well cleaned and degreased and pass water bead test.

Voltage and current is from a CC/CV power supply 55v/10a and both are correct and tested with 2 VOM's.

Not getting loose connections. ( well have got a few but easy to tell when that happens)

Set Amps (current) on power supply and Voltage always shows within 5% of what 720 calculator says they should be, so pretty sure I am figuring surface area correct. ( but they never seem to go down- just slowly go up to the 15-20 peak volts that the calculator says).


Acid mix is Napa battery acid mixed 1 part acid to 3 parts bottled distilled water ( 2 gallons to 6 gallons in big cooler.

Hold ano temperature between 68-72 - and doesn't look like I am getting any dissolution as no chalky stuff on parts.



BUT, I set up my ano about 2-3 weeks ago and While waiting for some more dye, HT sealer, etc. from Caswell I had left my cathode ( 12x12x0.? roofing flashing - well cleaned and sanded and cleaned some more) in the tank.

in the 2-3 weeks it had totaly disolved so had to make another one.


So after all this, My question is, can too much dissolved Al in the Ano tank cause the ano layer to be to thin? or what does it cause?

I have read through the threads and do not have the equipment to do the titration test and will just replace the ano bath as it is cheaper and easier than all that.

Unless someone has any other ideas.

[destroyer125]

You will only need 15v total and 12ASF. You will use 15 volts no matter what.

[ron83]

Destroyer125,

Guess I should have explained better. When I use 1mil, 6ASF it goes to 15v, but, just to experiment I did 8ASF (90min) to cut time and see if time in tank was getting disolution and then my power supply showed right around 20 volts.

Isn't 12ASf outside of LCD specs? or am I reading that wrong or not understanding correctly?

The 55volt/10amp is the max my power supply will do. I still set/turn voltage knob all the way up and then set the current/amps knob at whatever the 720 calculaor says for part being done and let it run.

=72 square inches = .5 square foot at 1 mil = 6 ASF = 3 amps for 120 minutes with peak voltage of 15v. which my power supply normally shows voltage around 14-16 volts and hold amps at 3.

[destroyer125]

try doubling your amps and running for the same time. I mainly use CV anodizing even thougn caswell doesnt support it. I try not to preach about a different method. Run the parts as if you had a full 1SqFt piece

[sswee]

ron83,
Your numbers are good. LCD anodizing by the book is 3 to 6 ASF. It's set up for the hobbyist. Many of the guys that have been doing ano for a while play with or use the higher CD's. I run 8 ASF myself for the time reduction.
A higher aluminum content increases the conductivity of the tank. Usually running more current through the parts than wanted. Your voltage readings don't seem to show a problem. As far as the voltage going to peak and staying, the coating can grow in thickness but the pore size increases maintaining the same resistance of the coating.

What indicates your coating thickness has decreased?
SS

[ron83]

Destroyer,
thanks, will try and experiment a little.

Sswee,
Nothing idicates a thin anodized layer except my eyes. I guess looking at quite a few things that have been commercially anodized, it almost looks like a nice lacquer paint job on them. Where as most of what I have done, looks like a thin layer of stain on the aluminum with the grain of the aluminum visible. I have been using the 720 rule, and have done 6 and 8 amps, at .5,.75, and 1 mil for thickness, using Black and the Blue 4a caswell dyes.

[acidrain]

Are you heating your dyes?

[ron83]

Yes, to 135-140 degrees and leaving in for 30 minutes.
and Im not letting it dry between ano and dying. Spray it over the ano tank with Distilled water then dip in distilled water then right to the dye bath.

from what I have read I would guess I am loosing connection but have double checked them many times. If I take a piece off the rack when anodizing multiple pieces the volts drop. then as soon as put back on it goes back to around 15 volts so assuming they are good. all parts and connections are bolted, beaten, or threaded in tight and using Al wire (welding and Radio Shack) but have some 1/8" Titanium rod on the way and bought a butt load of titanium bolts off ebay so will see what that does.

The best piece so far had a nice golden brown tint to it when it came out of the ano bath, the worst just looked like plain AL .

So what are some secrets to getting a thicker ano layer?

[sswee]

The best piece so far had a nice golden brown tint to it when it came out of the ano bath, the worst just looked like plain AL .

The yellow to golden brown is an indicator I look for on the thicker coatings. Normally 1 mil+. It is where I get the best blacks and Blue 4A.

So what are some secrets to getting a thicker ano layer?

Drop your tank temp and use the higher CD's. Both combat dissolution.
8ASF has always worked good for me but I run my tank at 60*. The cooler temps will incease the peak voltage slightly. The more juice you run the more heat. Other than that, increase the run time.
SS