Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Anodize Dye Problem
What would cause the color/dye of a Type II anodized part appear to be mottled or inconsistent on a part surface. This apppearance is random but usually on the corners or radii of a given part.
Alan B. Pirnat- Willoughby, Ohio
Mottled usually means incomplete removal of organic soil (cleaning). You mentioned high current density areas, so that could be burning or just barely too much current to get the same pore structure in the high current density areas. A proprietary glycolic type additive might help. Also if the dissolved aluminum is high it will clog the pores more in the highs than in the lows and thus contribute to dye inconsistency.
Come back to me with dye temperature, aluminum alloy, dissolved aluminum, and let's brain storm some more!
Take two aspirin and call me in the morning.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
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