The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Is non sealed anodized suitable for external use

Can anodized aluminium without a seal be used externally ? If yes how long would it last in non sea area environment. Can anodized aluminium with out a seal be used in place of Aluchrome to provide a suitable surface to powder coat ?

Best Regards,

Richard Rinn
Insight Sign Systems - Glasgow, Scotland, UK

---

Heavy hard coat anodizing is sometimes left unsealed to retain the maximum hardness. It can be done. But unsealed anodizing will not only have greatly reduced corrosion resistance, it will be a magnet for soils, dirt, and stains.

Yes, it probably can be powder coated, although it might take a study of the whole coating system to say whether it's a sound plan or not. It would however, almost surely cost more than chromate conversion coating.

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

---

To my knowledge, the only reason for not sealing a anodic coating is for hardness/wear resistance. The sealing process decreases these properties. If you don't seal, you will have an anodic coating with "open" pores..which will be succeptable to corrosion, and.. in the case of dyed parts.. rapid fading. You can powder coat over sealed, or non-sealed anodizing, as long as the parts are free from dirt/oils..ect.

Marc Green
anodizer - Boise, Idaho