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topic 30092

How to etch and color anodized aluminum


A discussion started in 2004 but continuing through 2019

2004

Q. I need to etch and color letters on anodized aluminum plates for signage for a new building. I haven't done it before and don't know where to start. Being screenprinters we do etch brass. Is it more or less the same process?

Jurina Krynauw
Screenprinters - Stellenbosch, Cape Province, South Africa


2004

A. My dear sir, etching and colouring on aluminium plates and alloys is possible. Please provide the full drawing and the procedure being adopted by you so that we can guide you.

Ajeay Kumar
- DELHI, INDIA


2004

Q. Thank you for the response. All I want to do is the word LABORATORY (In a bold arial font) etched on natural anodised aluminum and filled with blue. The size of plates - 400 mm x 35 mm and lettering - 20 mm high

Jurina Krynauw
Screenprinters - Stellenbosch, Western Cape, South Africa


2004

Q. I have the problem of wanting to recoat some bronze coloured anodized aluminum.

Neville Westbury
- Melbourne, Victoria, Australia


2004

A. Jurina: Yes, the aluminum can be etched and colored. letter 22035 describes some etching procedures. After etching and desmutting you could anodize, then silk screen the blue filling, then seal. That's one way.

Another way, perhaps easier and better, is to mask everything except where you want the lettering, then etch, anodize, dye with blue dye, seal, and remove the masking.

Neville, your problem is a bit different. The anodizing needs to be stripped, then the aluminum re-anodized, then re-dyed. Bronze aluminum for outdoor use is usually not done with organic dyes (because of lack of light fastness) but with a special "two-step" process that electrolytically deposits metal in the pores as a bronze "dye".

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


2005

Q. I am trying to etch a aluminum sheet.

I want 3D effect designs to be coloured etching on aluminum sheets.

Please guide me

Thanks

DILIP DODIA
windoors - MUMBAI, MAHARASTRA, INDIA


2005

A. Hi Dilip. You can etch, anodize, dye and seal as previously described, but sorry, I don't quite understand what you want. Please provide a photo, or a reference, or additional detail. Thanks.

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



August 16, 2013

Q. We are currently Etching SS Plates, but wish to know --

1. How to etch colored anodized aluminium?
2. Will it etch by HCl? If yes, please suggest proportion?
3. If no, what should be use?
4. Does it gives sharp result and will it show the base color of aluminium?

Nilesh Sinkar
- Maharashtra, India


August 22, 2013

A. Hi Nilesh. What you could try if you wish, is masking what you want to leave unetched, and then selectively removing just the anodizing with chromic-phosphoric acid (per letter 3397), which would leave bare aluminum covered material there. Obviously this etch would not be very deep, but it should be sharp. Otherwise, see letter 22035 for the various aluminum etchants and techniques. Good luck.

Regards,

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



August 28, 2019

Q. Hi, my name is Mike Judge and I have a question about stained aluminum building materials that may relate to this topic.
Wet concrete tile mortar has been deposited on the aluminum threshold of our exterior door and allowed to dry. When the concrete was cleaned off, it left an unsightly stain that can't be removed with cleaners. The chemicals in the concrete appear to have etched the aluminum.
If that etched area can't be removed, is it possible to etch the entire threshold to regain a consistency of the patina? I've heard of etching aluminum with bright colors, but in this case it would need to be more subdued.
Thanks in advance for any help you can provide.
Regards,
Mike

Mike Judge
- GRIMES, Iowa, USA


August 2019

A. Hi Mike. Concrete is alkaline, and alkaline materials can attack and etch aluminum. So your interpretation of what happened seems reasonable.

But the cure might be prohibitive. A finisher would need to clean the aluminum, etch it deep enough that the stain has hopefully been removed, probably de-smut it, anodize it, and seal it. Time is money, and processing one threshold is sufficiently time consuming that, unless the threshold is really special, replacement is probably less expensive than repair. Good luck.

Regards,

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

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