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topic 60447

Reducing smallest trace of salt on the surface before coating


May 2, 2017

Q. Hello everybody,

I face a difficult salt problem in my company.
Some of our clients impose us to have a chloride sodium (NaCl) rate on the surfaces of our devices below 1,8 µg/cm2 (= 18 mg/m2).

We use the Bresle patch method to determine this rate.
As an indication, our tap water show a 600 mg/m2 salt rate.
After meticulously degreasing our devices, we still have a rate around 100 mg/m2.
We tried some industrial products to apply before coating but none of them met our expectations.

I am starting to believe that our only option is to wash our devices with ultra pure water (type III).
So here is my question : have any of you already faced this kind of problem?
Do you know what solution we have to remove even the most tiny trace of salt?

P.S.: We apply coatings on raw aluminium, steel, inox. All that with or without cataphoresis. And we are far from any source of salt.

Thanks in advance for any information ! =)

Ludovic Dumont
Process engineer - Paris, France


May 2, 2017

A. Sodium chloride is very soluble in water which is the best solvent to remove it.
The water must be ultra pure.
Degreasing by any method is useless and probably a source of sodium chloride.
You are trying to detect very small amounts of contaminant so the patches must be handled with great care. Contaminated patches are a common source of erroneous readings.

geoff smith
Geoff Smith
Hampshire,
       England



May 3, 2017

A. In general, ultra-pure water is not required, but a DI water rinse with a conductivity of <5 µS is usually sufficient to meet your specs.

Lyle Kirman
Consultant - Cleveland Heights


May 4, 2017

Q. Thank you for your answers.
I hoped there was a cheaper method than washing everything with DI water.
Did anyone ever find a degreaser which can also get rid of salt?
And thank you Geoff for your advice about patches' contamination but, sadly, I found it out "in the field" ^^'

Ludovic Dumont
- Paris, France


Salt-Away

May 2017

A. Hi Ludovic. There are proprietary formulations which claim to remove salt. It would be interesting if you tried one and told us the result of your surface analysis after using it because we have numerous threads on the subject.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


May 10, 2017

Q. Okay, I already bought a bottle of "Chlor*Rid" and tried it manually (without dilution and pressure). I had to rinse my samples with ultra pure water after that and the results were kind of random (between 12 and 70 mg/m2).
We consider degreasing with a process involving steam distilled or DI water, added with a degreaser and Chlor*Rid.
I'll tell you if it's working! However if you have any tips, I'd be glad to read them.

I just spent 1 hour seeking threads about salt removing on this forum and I just find the discussion going on since 1995 ^^ (https://www.finishing.com/0000-0199/071.shtml)
You still cannot compare the different products here?
If you know some other guys working on this I would love to speak with them. Or let me know if there is an ongoing thread here where people work on that.

And thanks for your answers =)

Ludovic Dumont
- Paris, France


May 2017

Hi again. All threads here are ongoing, but we started a new thread for you rather than appending your inquiry to another because no applicable ones were really active. Everyone naturally wants all services tailored to their exact desires of the moment, but that isn't always possible. This is deliberately a "no registration required" site, and thousands of postings over 22 years have proven repeatedly & absolutely that testimonials and comparisons of name brands cannot work in such a format. For example, we've received numerous testimonials offered under fictitious names where the IP address of the "satisfied customer" was the IP address of the product's website :-)

If you were the sales manager for a product, would you let stand a recommendation for a competitive product without posting paragraphs of spam (as happened here repeatedly), posting fictitiously (as happened here repeatedly), or threatening legal action (as happened here repeatedly)? Ideas like "Android is great but Apple sucks", or "Chevy Trucks are fabulous but Ford & Ram trucks are worthless", or "Salt Remover X is much better than Salt Remover Y" are 99.9% worthless fanboy stuff anyway.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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