Where the
world gathers for metal finishing
Q&As since 1989


-----

Black Anodize Turning Brown

Has anyone heard of black anodize, class II type II turning brown? If the seal was not good enough, would it cause the browning?

Daryl Gillum
- Santa clara, California
2001

---

First of two simultaneous responses-- 2001

Hello Daryl,

Poor seal and/or exposure to U.V. light can fade the color. Have a sample part seal tested. One such test is dye absorption. Check with your local anodiser to see if they offer this.

Good luck,

Bill Grayson
- Santa Cruz, California, USA

---

Second of two simultaneous responses--

You did not say the conditions for turning the black color into a brown color. I have seen the black parts that are well sealed turn to brown color under a temperature of 80 °C for 20- minutes. This has to do with the heat resistance of the black dye.

S. Y. Yuen
- Hong Kong, China
2001

---

Hi Daryl,

I have a similar problem w/some parts from my customer turning brown. Did you happen to find the cause of this problem.

Trung Nguyen
- San Jose, California
September 10, 2008