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Is salt spray test justifiable for zero micron coatings?

Sir, my coating has thickness of 0.0 microns.and technical people are asking for salt spray test to conduct . according to my knowledge salt spray test is conducted only on zinc, cadmium and nickel coating with least thickness of 30 microns .so is it justifiable to conduct salt spray test on my coating which has no thickness? if yes, please let me know in hours

Sagar Deshpande
student - India
2007

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It is possible to conduct salt spray tests on any coating or even a bare substrate,Sagar. But at this point it will only add another layer of questions and obfuscation, and there is no way of saying what the right number of salt spray hours is. Please introduce the topic by explaining what you are trying to do and why. Thanks.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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2007

Sagar

To have a coating implies thickness. It may happen to be less than conventional measuring techniques will quantify.

A chromate conversion coating on aluminum is similar, yet to be compliant to various specifications, it must pass a 168 hour salt spray.

To answer your question, yes, the testing is justifiable. How else do you know your coating is meeting a requirement?

Willie Alexander
- Colorado Springs, Colorado

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2007

Dear Sagar,
Is the word "coating" confusing us all? Take the following sentence (not very good English but it does make sense) "The coating we supplied using the clients coating process, has been approved. The applied coating will now be evaluated for salt spray resistance".
a) The first 'coating' refers to the material
liquid/powder).
b) The second 'coating' refers to the application.
c) The third 'coating' is referring to a material that has already been applied to a substrate.

The word 'coating' used in the context of a & b would not have a film thickness associated with it.
The situation I think is that - you have produced a 'coating' (liquid/powder) that your tutor now wishes you to evaluate. To carry this exercise out, you must first apply your 'coating' (which has zero microns), ensure that it attains complete cure -- then submit this applied 'coating' (that could be 60 microns) for salt spray evaluation.

Terry Hickling
Birmingham, United Kingdom