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Problems in developing anodizing dye

Dear Sir,

My company is an electroplating company, and keen to develop our own color dye but failed I suspect the problem lies with the color's particle size. Maybe too big for the pores to absorb... I would like to know with regard to suitable anodising color dye: What is anodising's average pore size? What is Color pigment's suitable particle size?

Hwa Ping
electroplating - singapore
2003

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As for pore size, please see letter 19297, and there are a number of published articles on this topic if you do a computerized search of the metal finishing literature. Metal Finishing Information Services in the U.K. offers a compilation of metal finishing abstracts as a CD-ROM, an on-line database, or personalized search service. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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2003

First, anodize dyes are soluble chemicals, not inexpensive pigments (as used in paints). Some important properties are that the dye molecule adsorb to the anodize pore walls and resist fading. The latter could require long-term testing. As you suspected, pigment particles are too large for conventional anodize pores.

Of the literature to which Ted alluded, I recommend The Surface Treatment and Finishing of Aluminum and Its Alloys by S. Wernick, R. Pinner, P.G. Sheasby. A huge source of information on anodic coatings (including pore size) and the dyeing thereof.

These sound very relevant (although I haven't seen): Anodizing and Coloring of Aluminum Alloys ⇦[this on Amazon affil links] by S. Kawai (2002) and the "Aluminum Finishing" MFIS CD-ROM

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.