kapoor1_1

Topic: Rusting spots occur on electroplated lacquered surface after few days.

I am facing a problem that after electroplating CRC pipes i.e electroplated brass and nickel, I lacquer them but after few days rusting spots occur. If require I can mail you the pictures sent by my customers.

During my process, we pretreated items properly and after plating we wash it with sodium dicrobate and after drying properly, we lacquerd it. But after few days or after month, rusted spots occur.

Plz guide me, I will be very much thankful for it.

Puneet

jimtrottier

Re: Rusting spots occur on electroplated lacquered surface after few days.

It sounds like your laquer is not doing the job. I would check your laquer gun to see if it is operating properly and ask your laquer supplier for his input, also check your air supply to your gun for moisture. In my opinion it's not in your plating but the laquer and it's application.

Jim

DustinGebhardt

Re: Rusting spots occur on electroplated lacquered surface after few days.

Is this a new problem? Have your parts been free from rust previously, and only now are showing signs of early oxidation?

The lacquer and the electroplating are supposed to improve the corrosion resistance of the underlying metal. As Jim said, this problem could be a defect from the lacquer. But the fact that they are rusting so quickly could also mean that the nickel layer is insufficient.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

kapoor1_1

Re: Rusting spots occur on electroplated lacquered surface after few days.

Dear Sir,

Thanks for the reply. Regarding lacquer, we are using oven base dipping lacquer technique which help us to cover pipe from both side outside and inside. So there is no possibility for any gun moisture problem. Also I would like to tell you that besides the rusting spots which are present; the layer of lacquer also present there.

Regarding previously rusting, we polished each pipe properly two times with pipe polishing machine and then after plating process is done.

So please advice what is the reason if lacquer layer still present on pipe and pipe is well polished which removes previous rusting. We will be very much thankful for your guidance.

thanks

DustinGebhardt

Re: Rusting spots occur on electroplated lacquered surface after few days.

Unless you are stripping down to the base metal, polishing the base metal, and then going through a complete replate cycle, you are probably not removing all of the rust. The residual rust will easily come back.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

kapoor1_1

Re: Rusting spots occur on electroplated lacquered surface after few days.

Thanks dustin,

WE WILL DO IT FIRST NOW AND CHECK IFTHIS WORK. THANKS AGAIN


jimtrottier

Re: Rusting spots occur on electroplated lacquered surface after few days.

Rust is oxidation and needs two componants to grow moisture and oxygen. If your parts are thoughly dried as in an oven rusting should not take place and if your lacquer is working properly it should give it an airtight seal.

So that being said do you oven dry your parts after plating? Plating lines are a very humid area, is the lacquer applied away from the plating line in a drier area? Are these rusting parts being used in a steamy enviroment?

kapoor1_1

Re: Rusting spots occur on electroplated lacquered surface after few days.

Hi Jim,

After plating we put our pipes in open area to dry up. After 24 hrs, we do lacquer on it. Do you mean to say that after plating first we need to dry it in oven then put lacquer on it.

Secondly, you said that rust require moisture and oxygen,  as we have done lacquer and bake it in oven is it possible that moisture will dry up at 150centigrade automatically.

As you said lacquer will give airtight seal, our rusting spots are emerging even there is lacquer layer is present. What does it mean, we still not find this answer till now

Our lacquer unit is on seprate floor from plating line. Regarding steamy enviorment, we would like to tell you that our our rods used as curtain rod for home furnishing item and require transportation through ocean line to reach overseas. So it passes through salty envoirment before reaching final destination. Plz. tell me what will the reason of rusting spots even lacquer layer is present. We will be thankful for your guidance.

jimtrottier

Re: Rusting spots occur on electroplated lacquered surface after few days.

Yes a bake dry is the way to go. Try running your tube through your lacquer oven before you lacquer them and than again after lacquer. I suspect your parts are not totally dry after a 24 Hr. air dry.

kapoor1_1

Re: Rusting spots occur on electroplated lacquered surface after few days.

THANKS JIM, WE WILL TRY THIS WAY AND HOPE IT MAY WORK.IS THERE IS ANYWAY TO TEST RUSTING AFTER LACQUER

jimtrottier

Re: Rusting spots occur on electroplated lacquered surface after few days.

I am not sure of a test method because lacquers differ from one another, I would suggest you talk with your vendor on testing their products.  All items of this type are intended for indoor use only.

Another thing to consider is promptness after plating to drying and the application of lacquer, this should be done quickly, I suspect in your current 24Hr. air dry the nickel is already starting to carode even if it is not noticable to the naked eye which can explain the rust under the lacquer.

For several years I ran a similar operation of nickel and nickel and brass after the parts were unracked from the plating line they went on a overhead conveyor passed through a drying oven and continued to a thermoset lacquer spray booth than continued to a curing oven and exited as finished product. It worked very well.

Hope this helps you,

Jim 

kapoor1_1

Re: Rusting spots occur on electroplated lacquered surface after few days.

Thank you so much for your support. We will try with this way now.

Thanks Jim