Anodizing Tank Setup ?

[soaring]

I am setting up a 20 gallon anodizing tank and am using 1/2" PVC pipe for my aerator. In order to keep the pipe weighted to the bottom of the tank I was planning on inserting lead strips into the tubes prior to glueing them together. Does anyone know if this will cause any issues? I reasoned that since the cathodes are lead and the tubes are filled with air during the plating process that it should not hurt but want to make sure I do not ruin my acid solution. I can also remove the aerator when not in use. Thank you for any input.

[archimedes]

Greetings Soaring,
I too am a beginner so my observation will be
w/o solid experience so far. But, have you
looked thru some of the Anodizers' photo
albums? I did and I saw some very nice setups
with the lead sheet placed over the PVC tubing.
SS's photo album comes to my mind ---
Engineered well --- solves 2 tasks at same time!
BTW--- that is a big tank you are building.
Would like to hear how the progress goes.

[soaring]

I know lead must be acceptable as it is often used as the cathode but my concern is that they are not electrically tied to the cathode (not tied electrically at all) so will they become sacrificial at a higher rate than the cathode and contaminate the solution?

[sswee]

I just wrapped some lead sheet strips around the PVC to weight it down when I was using aeration. I don't take my lead cathodes out of the tank. It's been over a year and there are no signs of any problems. Also I have never glued the PVC together when using it for aeration. It allowed for reconfiguration when changing things around to find the most optimum setup. I tried several size holes at different spacing. The larger holes helped move the electrolye without creating as much mist. Just some points to ponder.
SS

[archimedes]

Just brainstorming---
If I remember correctly there was a previous post
that spoke of "moving" electrolyte around the part and
not just pushing air through a volume of electrolyte.
Perhaps the objective is to design an aeration function
that would "swirl" the electrolyte about the perimeter.
Perhaps igniting the air stream from opposite corners?
This 20 gallon project would prove a worthy test for such
as I am going to assume you intend to do a large volume
of product in one setup and therefore your temp control
needs will be pertinent.
Gathering the heat from the mass center of the product line
and move it to the tank walls for dissipation . . . . . . .
A 3.5 gallon tank wouldn't show much, but 20 just might.
scott

[sswee]

The purpose of aeration is multifaceted. It is to help keep the nitrogen bubbles that form on the part knocked off, keep electrolyte moving over the part to cut down the part temp. (a thermal pocket develops around the part increasing dissolution), and create an upwelling in the tank to help distribute the heat though out the tank to assist in dissipation.

I can't say definitely at what size tank or size load aeration becomes inadequate. I used aeration in my 20 gal. for a while but as I started to increase load size I found the need for more flow over the parts to help combat dissolution. With the guidance of Fibergeek, I decided on going with agitation instead of aeration. I plumbed a Little Giant magnetic drive pump made for acids. It had several benefits over the aeration. I still cannot max out a load size for my 20A PS due to heat being generated without additional cooling. I am using AC assisted ambient cooling. Most of this info has no bearing on smaller setups but are considerations for 20 gal or larger. Acidrain has excellent and consistent results using aeration. I don't recall the size of his setup but I think it is 15 or 20 gal.

SS

[acidrain]

My settup is ~35 gallons. I use both agitaion, and airation. With the added mist of airation, I found it necessary to add a vent hood with exterior ducting.
I also used 1/2in PVC for the airation manifold. It has four tubes running along the bottom of the tank at approximately 6in centers. These tubes are drilled at 1/16in every 4in. The manifold is weighted with the lead cathode, which runs down the side, accross the manifold on the floor of the tank, and up the other side of the tank. The air source is from my large shop compressor, which has a large in-line filter and regulator. Main line air is regulated down to 20psi, then regulated again at the tank for fine control.
Heating and cooling of the tank is done by running the PVC agitation line from the tank, through the acid pump, through a set of valves directing the electrolite to either a heated or cooled water tank, then back to the ano tank. Within the heated or cooled water tanks is the coil (a bunch of PVC pipe and elbows) through which the acid flows, and is either heated or cooled by the water as needed.
To answer your original question, yes you can use lead to weight the airation manifold without fear of damaging your electrolyte.
BTW, I glued all of my connections.

[soaring]

Thank you all for your assistance. I feel much more confident in my setup. sswee also raised the issue of temperature which I have yet to address. I too am running a 20A source so will order and acid pump and set up a cooling system. I made my first parts yesterday and they turned out gorgeous. I proceeded to laser engrave them on my CNC CO2 Laser which eradicates the pigment while leaving the oxide unharmed. I did both polished and bead blasted 6061 & 5052 dyed black and the laser rendered beautiful white text and graphics. Thanks Again

[archimedes]

Soaring,
Can you post some photos?
Sounds like a very cool project and part/product!
s-