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Ted Mooney, P.E. RET
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for Metal Finishing 1989-2025
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Power Outage During Salt Spray Test
Quickstart (no readers left behind):
Accelerated corrosion testing is ubiquitous in the metal finishing industry, and is generally called salt spray or salt fog testing. Sample parts are put into carefully designed chambers and exposed to a specific temperature and a fog of specific salt concentration (and possibly other specific corrosive agents) for a given period of time.
At worst, they are a good QA tool, giving early indication is something has gone wrong in the processing that will cause reduced life.
At best, some people feel they may have some limited predictive value for real life, although others feel that corrosion is such a complicated phenomena that no accelerated test can properly simulate real-life corrosion.
Q. Hi,
I'm the plating manger at an Aerospace finishing shop in Florida. We've been in the process of setting up our own salt spray cabinet for internal testing. So far the testing is going well, but being that we are going into the rainy season I'm concerned about losing power during our test due to the bad storms. My question is what would the recommended procedure be for logging and continuing the test after we regain power?
Thanks for your time.
- Oldsmar Florida
March 18, 2025
A. Hi Andrew,
If this were for your company's own internal use you would get to write the rules. But because you are in aerospace, the answer is almost surely that the test has no validity if it was done in start stop fashion. Sorry to deliver bad news.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Andrew,
I would think that for salt spray, realistically, one interruption would not affect the outcome by any meaningful amount. At the very least, I certainly would not expect a "false pass" to result. However, in the manufacturing world, any deviation from the accepted procedure can be legitimately objected to, if somebody chooses to make an issue out of it.
Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois
A. Buy an UPS, uninterrupted power supply, for the chamber. You should be able to get 4-8 hours of power so the test can be run without interruptions. If the power is out longer than that you might have to retest.
GEORGE SHAHINretired chemist - Rock Hill, South Carolina
⇩ Related postings, oldest first ⇩
Chromate Conversion Coating Salt Spray Failure
Q. Recently received notification from an outside laboratory that All our salt spray samples for conversion coating failed. There was a note on the bottom of the test report that their salt spray chamber lost power for 24 hours during our test. Could this be the cause of our failure or should I be looking elsewhere. We have been passing fine before this.
Ray Handwerker- Bensalem, Pennsylvania, USA
2002
A. Hi Ray,
Your question lacks specifics (e.g., you don't really define failure for your test), so any answer you get here may not necessarily address the problem. The fact that the cabinet was off for 24 hr is not a good sign. I will assume that the cabinet has run almost continuously in previous tests. Is it the cause of the problem? Hard to say, but it is a culprit. Check my reply to letter #17172 for hints on where to start looking for clues on the pretreatment and painting side of the equation.
by Gustavo Cragnolino (ASTM)
on AbeBooks
or Amazon
(affil links)
- Naperville, Illinois
A. Ray - It's hard to say whether 24 hours w/o power would make a difference without knowing the total length of the test. The most important question is...Did the lab add another 24 hours to the end or just leave the samples in the chamber?
Cynthia L. Meade- Sylvania, Ohio, USA
A. No one could state that your parts failed. The test conditions are clearly specified: collection rates, degree of angle, temperature, etc. Certainly the lab violated the temperature and collection rates and a host of other conditions during the time the cabinet lost power. One thing I'd suspect is that when the temperature of the cabinet started to drop, the corrosive 5% salt solution condensed directly on the panels. This would be far more corrosive than the salt spray alone. I'd go back to the lab and insist that they re-do the test for free! Your entitled to it!
Milt Stevenson, Jr.
Syracuse, New York
A. Hi Ray,
Since this incident is so 'sudden', I can't tell if your test is failed. Like others, I'd suggest you could discuss with the lab personnel what happened during the power failure-resume interval. My application (proposed by JIS) is SST shall be carried out through CONTINUOUS time (24, 48, 100, 200 hrs). Sometimes, machine breaks down/maintenance, run out of DI water supply or power failure. We will retest the samples, and this always happened when we're undergoing the 200 hrs SST.
To share with you guys
According to Robert Baboian:
"The salt spray fog test, when it's used properly, is one of the most valuable corrosion tests in the world. It has impacted all industries. It has been very valuable in terms of quality control and comparative behavior materials and that's in all walks of life: in the automotive, aircraft and compliance industries, in transportation and infrastructure. Paint coatings are used in all of these industries."
"The test is used widely for paint systems. When it's used properly, for quality control or comparing behavior of materials, it is extremely valuable. For example, cyclic tests that are used now in various industries incorporate the use of ASTM B117. These tests are extremely valuable because they more closely duplicate what happens in service."
Seems like there are many critical parameters to be properly controlled in order to obtain reliable SST result
Chee Hong, Lee
- Singapore
Salt spray tests do a great job of predicting how materials will react in a salt spray test :-)
- Honolulu, Hawaii, USA
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