The authoritative public forum
  for Metal Finishing since 1989
-----

Anodizing ID of 6061 tubing

August 27, 2009

I need to find out if its possible to anodize the inside of a aluminum tube that is 5/16" OD and a .033 wall.The length of the tube will be 4-1/4". Any help with this would be great. Also I need it to be FDA food contact approved.It would be great to have it finished in a variety of colors.Not looking to do this myself but need information for getting these manufactured.

Thank You,
Adam

Adam BOehm
Product Designer - Ruidoso, NM, USA

---

First of two simultaneous responses -- August 31, 2009

Gut feeling is that FDA will not approve most colors on anything that touches food. Better check with FDA to see what is and is not allowed.
Anodizing the inside of a tube of that dia is going to be tough. It probably can be done with proper racking and solution flow thru the tube. Do not expect it to be uniform.

As a job shop, I would not even bid on the job unless there were thousands per year.

James Watts
- Navarre, Florida

---

Second of two simultaneous responses --

Hi Adam,

Interesting..

Though I haven't yet tried, make the job anode by passing thru' an appropriate diameter aluminum wire through the center of the tube(job) and make the wire cathode. Which should work.

I am not awreof FDA approved Anodizing but anodizing is very widely used in cookwares.Rememeber seal the anodic coating only with D.I water. I also doubt for approved dyes. Because may dyes may not be good for health.

Good luck

Keshava Prasad M
- Chennai, India
September 1, 2009

---

September 11, 2009

Mr. Keshava is right...work with an inner wire or round piece of aluminium inside the tube. Connect it to the cathode and start anodising.

Be careful that the inner tube (cathode) will not touch the product (anode) you're anodising.

Harry Goossens
- Netherlands