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Letter 148
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----- Absolutely! I don't have 'hands-on' in this, so I can't give you the process step-by-step, but I do know that anodizers commonly anodize aluminum plates, silk-screen the legend onto the plates, then seal the inks into the anodized film.
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 Surface Finishing and Treatment of Aluminum and its Alloys, Wernick, Pinner & Sheasby |
Regarding putting pictures on aluminum, there has been a process for doing this for at least 20 years. I don't have the article I read about this anymore. You would have to go to a technical library and look it up. As I remember, it involves absorbing the photographic silver salt chemicals into the porous anodizing coating. This would have to be done in a light-tight room with only dark room red lights. Sorry I can't help you more.
joseph l. andersom, jr.
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The process the writer is referring to was developed by Peter Laakmann of Synrad Corporation (CO2 lasers) and first published in the early '90s. Basically it involves laser etching the desired information into the anodized plate, then using the remaining anodization as a sort of resist. Dye is applied to the etched areas, given a few moments to be absorbed, the excess wiped off the resist area, and the whole is sealed. Synrad is in a northern suburb of Seattle, I'm sure they can supply a copy of the article. Problems are: a) its labor intensive; secondary and then *tertiary* operations, and b)frankly, we've never had particularly good success with it, although I can't say we've really applied ourselves to getting it right either. Laakmann claims it works great.
What about re-anodizing plates which have been selectively laser-etched back down to bare metal? Has anybody had any experience with this or similar processes?
Josh Drexler
Pepperell, MA
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--- Try
Ed. note 11/27/06: that page is apparently no longer functional
+++ Regarding the use of lasers to create colored letters - The process is actually quite simple. You use the CO2 laser to burn off the anodize layer down to the bare aluminum. Then you use an active colorant, like an alcohol based ink (sharpie marker) which bonds to the bare aluminum and voila, permanent stain in the aluminum. If you look at older Synrad lasers, the faceplates were all labeled in this fashion. If done manually it is time consuming, but if done correctly, you end up with a mark that is essentially a colored anodize layer. This can work pretty well in conjunction with a laser marking system to scribe in the pattern in the anodize and color it in afterwards. Daniel Perreault
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