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How to etch aluminium coating?

How do we etch an aluminium coating from a aluminium base material without etching the base material. Using chemical reactions?

Sivaganesh Muthusamy
surface treatment engineer - Shah Alam, Selangor DE, Malaysia
2007

Exactly what aluminum coating are you referring to? I can think of chem film, anodize, dry film lube, paint and flame spray for starters.

James Watts
- Navarre, Florida
2007

Actually it's flame spray.

Sivaganesh Muthusamy
surface treatment engineer - Shah Alam, Selangor DE, Malaysia
April 4, 2008

Hi, Sivaganesh. The stripping chemical has little knowledge of the history of the part, and no knowledge of your needs, and cannot distinguish one area of aluminum from another based on your desires. So it is not easy to remove an aluminum coating from an aluminum substrate without removing any of the substrate.

One approach that might possibly work is to anodize the item, converting the aluminum coating to anodize; this will strongly tend toward giving you a consistent thickness because of the electrical resistance of anodized coatings. Then you can strip the anodized coating quite selectively. Good luck, and please let us know if you try this, because it's based on theory not practical experience :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 13, 2009

Can you give the comparison between Galvanizing & CRC powder coated sheet? Which is better against Corrosion resistance , Salt spray test , EMC compatibility..... Regards,

Anand Tambe
- Pune, India
March 13, 2009

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March 17, 2009

Hi, Anand. The big difference between these is that galvanizing is a metallic coating, and it offers galvanic protection (the zinc coating will protect the substrate even if scratched), whereas the powder coating is a barrier layer coating. Powder coating is, to most people, more attractive; and it's probably less expensive. In the real world, galvanizing is probably more robust, although powder coating may outlast it in a salt spray test.

But I fear that you will find it impractical to try to find a "general solution" to which is the "better" coating. Rather, I think you need to start with the needs of a particular part in a particular situation, and then think about what coatings may meet those needs.

Trying to approach it from the direction you are trying to do it is sort of like asking whether travel by train is better than travel by ship, without specifying the start and end points. It can result in nothing but wasted effort if the points are separated by an ocean or are landlocked :-)

Good luck!

Regards,

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