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topic 31391

Stripping/removing cadmium plating safely

Please see also --

Topic 3212, "Stripping Cadmium plating and choosing a method"



Current question:

December 16, 2020

Q. Safety Considerations for Stripping Cadmium Plating from Steel Using Ammonium Nitrate Solution Per MIL-STD-871?

I will be stripping cadmium plating off of mild steel parts and plating with zinc with dichromate conversion after repairs have been made to the parent material. Embrittlement is not a concern.

MIL-STD-871 [link is to spec at dla.mil / Defense Logistics Agency] uses a blanket statement for safety "CAUTION: Some materials listed in this document are classified as hazardous and toxic substances." Personnel exposure to such materials shall be within the limits specified in OSHA Standard Title 29 CFR 1910-1000 Subpart Z." In the aforementioned CFR and the MIL-STD, there is very limited information regarding safety equipment or apparatus for using Ammonium Nitrate Solution for stripping Cadmium plating. I am very aware of the dangers of Cadmium and that the waste generated is hazardous. The disposal will be done through the proper channels.

My question is, are any gasses given off from the solution poisonous? Are surrounding materials (i.e. steel parts, machinery) in close proximity going to accumulate corrosion?

Thank you very much for your responses.

Brandon Sayles
- Monroe Wisconsin




Previous closely related Q&A's starting in:

2002

Q. When abrading a surface that is Cadmium plated should precautions be in place for the plating that is being removed? i.e., rubber Rubber Gloves [affil. link to info/product on Amazon], face mask? Can the material being removed be absorbed through contact with your skin?

Scott Adkins
Northrop Grumman - Huntsville, Alabama


2002

A. Without knowing the details, I think everyone would agree that breathing cadmium dust is not a good idea.

victor waldman
- Naugatuck, Connecticut


2002

A. Cadmium plating is virtually always chromate conversion coated, and the chromate can probably be absorbed through the skin to some extent.

When working with a toxic material like hexavalent chromium, plus a cumulative poison like cadmium, I certainly think you would need proven local ventilation and PPE.

I don't know the details of your situation, but it would probably be better to chemically strip the chromate and cadmium before machining if possible.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



2004

Q. I have steel bolts that are cad plated and I need to remove the plating safely.

Betty Ryan
engineering - Clearfield, Utah, USA


2004

You can remove it either by blasting or by a short immersion in muriatic acid.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


simultaneous 2004

A solution of ammonium nitrate in water is safer and will cause less problem with hydrogen embrittlement than muriatic. If you strip bolts, consider a 375 °F bake for 4 hours after strip. Not required if blasted.

James Watts
- Navarre, Florida


2004

Metallic cadmium IS toxic as opposed to other hazardous plated metals for which only their solutions are. So, in both instances suggested you will have to consider the outcome toxic and dispose of it accordingly, be it the blasting media or the spent hydrochloric liquor.

Guillermo Marrufo
Monterrey, NL, Mexico


A. Hi again. James is right that ammonium nitrate is usually a better stripping method than hydrochloric acid. Please see Topic 3212, "Stripping Cadmium plating and choosing a method".

Luck & Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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