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Blackening aluminum for solar collection

I am building solar panels for my shop and have some 4 X 4 sheets of aluminum, very thin , I think they were originally used for some type of photography. I would like to chemically turn them black insted of painting them do you have an idea that would be economical?. I used to work for Rosemount Inc in Eden Prairie and we would dip our aluminum exacto ⇦ this on eBay or Amazon [affil links] blade handles in something to turn them black but I don't know what it was.

Thanks,

Peter Rudh
sell cars - Rothsay, MN, USA
2005

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Take a look at www.finishing.com/339/56.shtml

Goran's method works very well for darkening Aluminum, I think that repeating the process would eventually give you a good rich brown black.

Marc Banks
- Elizabeth City, NC USA
2005

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2005

For best results you can use 2o% shellac solution(200 gm shellac/1 lit pure alcohol),just paint it on,when dry heat(slow) to max .400 C(if you think that is expensive you can use any edible oil or fat ,or even milk ,or egg white). Repeat if need.

Good luck!

Goran Budija
- Cerovski vrh Croatia

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Does anyone know how durable the darkened finish on aluminim is? Are any of the darkening methods more durable? Oil vs. Shellac,ect.. After darkening, is there a wax,coating,finish, that should be applied to enhance or protect the darkened finish?

Thank You

Gerald Garrett
Wilson Associates/Architecture - Oakland, California, USA
2006