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


-----

ASTM B633 appearance standards.

 

I am having two problems with Zinc plated material, plated per ASTM B633. One in that I am trying to locate appearance parameter standards after zinc is applied to cold Rolled steel? I am not looking for surface prep (substrate) appearance but rather Plating finish appearance (cosmetic) ie, rainbow, browning effect, etc. The second is what cleaners are safe to use on Zinc coated surfaces and how long do I have to wait to clean ie, fingerprints, streaks, etc...

Inquiring mind,

Richard A. Ornellas
- San Jose, California USA

---

Hi, Richard. There are no industry-accepted appearance standards (although maybe there should be). All you can do is make sample boards showing examples of what is acceptable and what is not. Good luck. You should try cleaning a test part with isopropyl alcohol [on eBay or Amazon] or acetone [on eBay or Amazon] after the chromate is dried (24 hours). But there should be no fingerprints or streaks on the parts.

Regards,

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

---

One of my vendors in Colorado Springs is zinc plating some chassis for us per ASTM B633, Type 1 with clear chromate conversion service class 1. After the parts come out of the tank at final rinse they have a white cloud appearance. This is not acceptable to our quality dept. and I could use some ideas on what that white residue is. Thanks

Ron Durham
- Denver,Colorado
 

---

Hi, Ron. A cloudy appearance can have a number of causes and your plating shop must resolve it, but probably the most common cause is a brightener imbalance. You probably will not be able to remove it, and it is probably underneath the chromate.

Regards,

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