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topic 50132p2

Salt Spray Test -- ASTM B117 Operational Problems

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A discussion started in 2003 but continuing through 2019

Can't hold pH in collectors high enough

December 2, 2013

Q. Hi !

I have some problem with the pH of my collectors in my old Harshaw salt spray chamber. My salt water solution is around 5% salt, I have to adjust my pH to 8.5 - 9.0 to get 6.50 - 6.60 pH in my collectors. I cleaned my salt water tank, my DI water tower, the chamber itself. All running conditions are good. I just have hard times to get my 6.50 minimum.

My pH-meter is well calibrated, buffers changed regularly, and temperature compensated.

I just don't know where to look anymore. The water is filtered, the salt is ACS. The filtered water is clean, but I have some microbiological contamination in my salt water tank. I'm running a test to see if I've got contamination in my collectors. Can it be caused by that?

Anyway, thank you !

Alex Fournier
Lab Tech - Galvano - Beloeil, Quebec, Canada

December 9, 2013

A. First, empty and scrub your salt water reservoir: it could easily be the biological contamination.
Otherwise, perhaps your feed tubes from the salt reservoir to the bubble tower need to be replaced: tubing is pretty cheap.
The main problem I've encountered with salt spray chambers is copper contamination in the bubble tower coming from the copper compressed air line. The water in the tower acts as a filter, and if you have a greenish-white buildup on the cylindrical casing, you need to dismantle it and get that buildup off. It dissolves easily with paper towels soaked in dilute (25 - 50%) HCl laid on the buildup for about 10 minutes - wipe & repeat if necessary. Though the manufacturers recommendations don't cover it, one should drain and refill the bubble tower once monthly to avoid this possibility.
I don't believe the copper issue has anything to do with altering the pH, but it helps with multiple other problems - like premature or false corrosion of test panels.

Fauna Tester
- Seattle, Washington, USA

February 28, 2014

Q. I scrub my water tank and all but my pH are still low. My salt water reserve has a pH of 9.00, the water coming out of the nozzle is still at 9.00. But the water in my collectors has a pH of 6.50. I cleaned my collectors, changed it for new ones, but the pH is still low. I really don't get it. What could bring down my pH like that? I tried boiling my collected water to remove the CO2 (like in ASTM B117), but nothing.

Any ideas?

Alex Fournier [returning]
Lab Tech - Galvano - Beloeil, Quebec, Canada

March 2, 2014

A. Hi Alex, did you check whether there were drops from the cover falling into your collector? This is impossible if you got correct pH at nozzle but incorrect in your collector; as you know, the fog drops into collector directly and contacts nothing after going out from nozzle. Or did you collect fog with products been tested? If yes, whether there were drops from products fall into collector?

Davey Shaw
Shenzhen, Guangdong, China

Specific gravity after collection is TOO LOW

December 18, 2014

Q. I has prepared 55 salt solution and I checked the Specific gravity it gives 1.040. But after collection it comes 0.9815. So what is the problem?

B Sankar
- Hyderabad,Telangana, INDIA

A. Hi Sankar. Although I haven't run a salt fog cabinet, I think it's some kind of measurement error. The specific gravity of pure water is 1.00 and it should be heavier with any salt in it.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Specific gravity after collection is TOO HIGH

December 18, 2015

Q. My pH is fine, making up my own solution. Unfortunately the Specific Gravity keeps rising. How do I get it back under control and keep it there? I've lowered the amount of salt but it's still reading 1.047 as of today.

Kay Lane
- Hazel Park, Michigan USA

Very high mass lost in salt spray test

May 8, 2015

Q. I have completed the panel testing in my Harshaw salt fog cabinet (96 hours following ASTM B117) and my results for loss of mass are extremely high at 7.22g of mass lost! I have good pH, specific gravity, level 4 DI water, and using a 5% NSS. Any insight as to why the loss is so great?

Tonya Moses
- detroit, Michigan USA

May 12, 2015

A. Tonya,
Use a calibrated temperature probe to verify that you are 95 °F. (A 10 °C increase in temperature will double the rate of corrosion.)

Dan Mack
- Horicon, Wisconsin

September 10, 2015

Q. Does anyone know the effect of running a salt-fog cabinet at 2 ml fog collection per hour versus 1 ml/ hr? With all other variables the same. Does it make a difference on corrosion of parts?

David Entrekin
- Madison, Mississippi, USA

Salt Spray cabinet collectors are collecting more than the required amount

September 16, 2015

Q. Recently, our Salt Spray cabinet collectors have been collecting more than they should. The collector closest to the chimney has been collecting over the required amount for several days regardless of the position of the atomizer. The other collector is within specification, but is also collecting more than usual. The pH has been within spec as well. The plant air pressure has not gone up, either. How do I reduce the amount in the collectors? What am I missing? Any help would be greatly appreciated!


Scott Acosta
Quality Auditor - Agawam, Massachusetts

September 23, 2015

A. Adjust (lower) the pressure regulator on the airline.

Fauna Tester
- Seattle, Washington USA

May 15, 2018

Q. Hello. I've recently noticed that the rate of collection in the cabinet collectors is higher than it should be. Instead of it being 1-2 per hour, it is roughly 4 ml per hour. Any ideas?

Abdul J Mathlib
- Paterson, New Jersey, USA

May 2018

? Hi Abdul. What is your response to Fauna's suggestion? Thanks.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Choosing a brand of salt spray test cabinet

December 30, 2015

Q. Picking a salt spray chamber.
Anyone had any experience with Inland salt spray testing chamber Model WTS 90. I'm trying to decide between it and Singleton.

James Langley
- Opp, Alabama United States

December 2015

thumbs up signHi James. Hopefully readers will discuss general aspects of salt spray chambers with you but, sorry, comparing brands is something that we have found to be incompatible with this no-registration-required site :-)

Most of the people posting here are real, but the anonymity of the internet has allowed shills to post with fictitious names here, posing as "satisfied customers" :-(

Plus, it has sometimes led to rancor instead of camaraderie, and it encourages spam. Apologies, but we do not post brand comparisons on the site anymore.

Good luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Salt spray cabinet problem: Blue buildup on atomizers

June 7, 2016

Q. We are running a ASTM B117 [affil. link to spec at Techstreet] salt spray chamber, recently I have seen a blue color build up on the atomizers. I clean everything and the next day it has build up again.

Does anyone know what could be causing this? I been running the salt spray testing for about a year and never seen this before.

Dave Clouse
- Monroe, Michigan USA

June 15, 2016

A. My guess would be copper contamination, probably from the air lines. Take an air filter off the line & swap the interior of the connecting pipe to check. If there's buildup, replace your piping. Also drain & clean your bubble tower, as it acts as a filter & gets contaminated.

Fauna Tester
- Seattle, Washington USA

June 29, 2016

Q. We often test large panels (10-15" in height) and smaller panels (6") at the same time in our Q-Fog chamber. Is there any concern that there is a "shadowing" effect if large panels are placed in front of small panels? Or even between the large specimens placed next to each other?

Olivia Isaac
- Sunnyvale, California

June 30, 2016

A. Good day Olivia.

I too, had the same concern as I had designed racks for panels some years ago, and had arbitrarily chosen 1.5 inches separation based on monthly panel requirements and square footage of cabinet area.

According to NADCAP regulations regarding salt panel separation:

"10 inch panels @ 6 degrees from the vertical shield approx. 1.0 inches."
"6 inch panels @ 15 degrees from the vertical shield approx. 1.6 inches."

See ASTM B117 [affil. link to spec at Techstreet] , Section 7 "Position of Specimens During Exposure."
Hope this helps.
From a fellow salter.


Eric Bogner, Lab. Tech
Aerotek Mfg. Ltd. - Whitby, Ontario, Canada

July 5, 2016

Q. Thank you Eric. Could you point me toward the Nadcap documentation? I'm not familiar with it, only ASTM B117.

Thank you,

Olivia Isaac [returning]
- Sunnyvale, California, USA

July 14, 2016

A. Good day Olivia.

Google "NADCAP Website" for programs, info...
There is a contact available.


Eric Bogner, Lab. Tech
Aerotek Mfg. Ltd. - Whitby, Ontario, Canada

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