The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Calculating the surface area of plating anodes

Hi,

I will be using titanium anode baskets in a 50 gallon copper tank.

The baskets are 9 inch wide and 8 inches high by 1 inch deep. How do I calculate the anode surface area if filled with 1 inch copper chunks

If I were to use copper slabs, how do I calculate the anode surface are accounting for the back.

Thanks

Ken Fefferman
- Harwood Heights, Illinois
1998

---

1998

Ken,

There is no correct answer since as the anode material is used, it is no longer one inch. Also, no two baskets of anodes will "nest" exactly the same. If the basket is against the tank, you can not count the back in area calculations. if it is several inches from the tank wall, you may get 20% effective area. You may see an effective 10% increase in the area of a basket of chips vs a slab, but this is going to vary over time.

I would assume 8X9=72 Sq In of area, up that to 80 and then watch your anodes to make sure that you are not over/under on your anode current density.

Does this help?

James Watts
- Navarre, Florida

I realize a lot of people are going to disagree with this, but in my experience using these baskets for copper, nickel, and silver anodes, I don't think you actually increase the effective surface area that much. Of course, the concept is that you have all the surfaces of each "nugget" in the basket in theory increasing the anode area to near infinite values. I found that the effective area is little more than that obtained by the actual dimensions of the basket. We still use them because of the convenience.

George Brackett III
silversmiths, Sherrill, NY
1998

---

I agree with you George, because the anode current densities suggested in the literature are not based on an actual study of the diffusion dynamics anyway, they're just empirical. That is, the researchers found that x was not enough anode, y was just right, and z was too much--then they had to tell the readers what y was. And I think they just used the envelope dimensions of the baskets to describe y because I've never read differently.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

If you are looking to keep a smaller anode mass in the tank with the same available surface area, try using round anode baskets.

The net anode consumption is the same but it is less expensive to get started when considering the cost of the anodes. Round baskets are also sturdier than rectangular baskets made of the same material. The disadvantage is that you need to buy more baskets.

You should get 1/2 pi (1.5+) inches of area for every inch of buss bar (times the depth in solution, of course). And it takes fewer chunks to fill in that same inch than if you have rectangular baskets. The round baskets are also easier to move around if you want to rearrange the electrical field and improve distribution.

Bill Vins
microwave & cable assemblies - Mesa (what a place-a), Arizona
1998