The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Chromate vs anodise in outdoor conditions

Dear Sir/Madam,

We use air/air heat exchangers for cooling outdoor cabinets. The two main aspects of such a device are the fans and the aluminium core. Though we are satisfied with a chromate conversion coating (Alodine 1200) for the HE covers we require anodising for the aluminium core. Some manufacturers are trying to persuade us that chromate conversion coating would also work for the core which is certainly going to face high levels of humidity during its life. Of course they 're trying to reduce cost. Do you think we can really trust the mil (Alodine) coatings for an aluminium surface whose thermal conductivity (K) is very important for the HE's cooling performance?

Thank you for your help.

Dimitrios Vergos
INTRACOM S.A. - ATHENS, GREECE

---

The same day you wrote this, we received a letter from someone else who uses chromate conversion coatings on a limited area of his anodized landing gear and finds it unsatisfactory corrosion-wise. If you change from a good process to a questionable process to save money, you won't.

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