Summary for 1000 hour salt spray Discussion
The thread on the 1000 hr salt spray RoHS question shows that there is no single universally accepted finish named as a guaranteed answer; several contributors stress that the result depends on what corrosion endpoint is required and what the part is made of. Faiz Jalal says stainless steel is an option, while noting passivation and non-hex chrome blue passivation have much lower salt-spray performance. James Watts says he has heard electroless nickel at about 0.0015 in. per side can reach 1000 hours, and that powdercoat over zinc phosphate may also do it, but advises checking with the plater or painter. Gene Packman emphasizes defining whether the target is red rust or white salt and identifying the substrate and critical surfaces. T.K. Mohan says 1000 hours is achievable with systems such as zinc nickel plus trivalent thick passivate, epoxy-pu electrophoretic lacquer, or zinc cobalt with sealant, but selection depends on the application. A later reply adds that e-coat may reach 1000 hours on tubular or edgeless parts, but not sheet metal edges, and that zinc iron with trivalent ch…
I have had a customer request for a plating/coating to meet 1000 hr salt spray
(ASTM B117) and also be RoHS compliant. Is there such a plating/coating?
Perry Longhurst
– Peterborough, Ont., Canada
2005
2005
Hi,
You can use stainless steel. Which is the best for your application. Passivation can withstand max of 500. Super black zinc passivation can withstand max of 500 hours to get Red Rust and max of 150Hr to Red Rust. Next best is Non Hex Chrome Blue passivation which will withstand 350 hours for Red Rust and 125 hours for white Rust.
Best Regards,
Faiz Jalal
– Hyderabad, India
First of two simultaneous responses —
I have heard that a minimum of 0.0015″ per side of electroless nickel will get to 1000 hours. I have also heard that a good powdercoat over zinc phosphate will get 1000. Check with your plater or painter.
James Watts
– Navarre, Florida
2005
Second of two simultaneous responses —
Both you and your client need to determine what type of corrosion you are looking for 1000 hours to. Is it red corrosion (rust) or white salt? On which significant surfaces? What is the substrate? What properties must the finish possess or not have?
Information is vital to getting accurate helpful answers and also to performing processing correctly in the clients estimation.
Gene Packman
process supplier – Great Neck, New York
2005
First of two simultaneous responses — 2005
Hello Perry,
It is entirely possible to exceed this 1000 hour standard. There are a number of coatings
Zinc Nickel alloy followed by Trivalent Greenish Thick passivate.
Electrophoretic lacquer of the Epoxy Pu type.
Zinc Cobalt allot with a sealant of the inorganic type after the light green thick chromate.
You need determine the end point of the 1000 hours is white or red rust and what is the base metal and where the component will be fitted before selecting from the myriad choices that are readily available of which the above is a sampler.
Regards,
Asif Nurie [deceased]
– New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016
Second of two simultaneous responses —
Electropolishing should get you to 1000 hours in a salt cabinet or more. I recall one test that was terminated at about 1200 hours… no rust yet on the electropolished stainless.
Todd Turner
– Monroe, Louisiana
2005
2005
Dear Perry,
I will add to what Asif Nurie said.
Alkaline Zinc-iron with followed by trivalent black passivation and a sealant will give you 1200+ SST Red Rust.
If you are more specific about your requirement and SST, I may be able to give more details.
Regards,
T.K. Mohan
plating process supplier – Mumbai, India
You should try E-coat. This will give you a minimum of 1000hrs salt spray. Most e-coat processes have a zinc phosphate pre-treatment. This is necessary to give the paint the proper adhesion. The mean thickness is usually .8-1.2 mils. This means that you can paint threads and small enclosures.
Adam Adkisson
– Seminole, Oklahoma
2005
2006
Hi Perry,
I’d like to clarify and add a few points:
1. E- coat may pass 1000 hours SST only on tubular/ wire/edgeless parts only.
2. Sheet Metal parts with edges will see shrinkage and will not get you past 1000 hours without Red Rust.
3. Zinc Iron that passes 1200 hours will contain Hex-Chrome. It will not be RoHS compliant. It is not an option.
4. Zinc Iron with Trivalent Chrome will not last 1000 hours.
5. You may require a duplex coat of zinc-nickel or zinc-iron plating with Trivalent chromate followed by a topcoat of E-Coat.
None of the above alone will work.
Khozem Vahaanwala
Saify Ind
Bengaluru, Karnataka, India
Q. Dear Mr. T.K Mohan,
I require 1000 hrs of Red rust in Zn-Fe Trivalent. Please guide related to my requirement.
Kuldeep
– Gurgaon-Haryana, India
December 26, 2012