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-----Phosphate and oil finish degrading?
June 16, 2008
Team-
For many years we have used a standard "off the shelf hardware" that is steel, that comes with a "PHOSPHATE PLUS ONE COAT SPECIAL OIL DIP" applied.
Until now, we have no reported issues with it (until now).
The mfr gave me this information on the part and finish:
Salt Spray Exposure - Red Rust: 72 Hours
Salt Spray Exposure - White Rust: N/A
Customer Cross Reference
GM: GMW3179 CODE G
Normally this finish is dark in color, with a satin luster.
We have found some that appear to be changing appearance, and have a whitish speckled look.
We actually sent some that appeared normal, from Houston to Japan, and they changed appearance during shipment.
I am not familiar with how a phosphate and oil finish looks when it degrades.
Does anyone have an educated guess for cause of color change?
Thanks for your attention,
product designer - San Jose, Ca.
Jon,
Have you realized you are using gelatinized steel pretreated by zinc phosphate and prevented by oil? The info from mfg is typical for your application; also, the difficulty you are running into is typical for phosphating operation. You may need some help to maintain your phosphating bath in good shape to consistently product dark parts.
- Cincinnati, Ohio
June 26, 2008
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