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Runs streaks in type III black dye

60302
October 20, 2016

Q. We recently developed an issue were we are getting "runs" under our black dye type iii. Was wondering if anyone could pinpoint the issue -- containments somewhere along the line, inadequate prep work or something completely different? This is 6061-T6 being bright dipped, then type III coated with black dye.

Chris Jones
product design & manufacture - Coopersburg, Pennsylvania
  ^- Privately contact this inquirer -^


October 26, 2016

A. Chris

The blemish looks to be the result of inadequate rinsing after anodize and before dyeing. To confirm, observe the blemish before unracking. Residual acid from the anodize is heavier than the dye solution, and will run down from the origin.

If this is the case, options include better rinsing (longer, agitated, cleaner), a mild nitric acid dip, and an inspection 1 - 2 minutes after immersion into the dye solution; while the parts are not yet black, the blemish will usually be visible. If found, repeat the two previous options and dye again.

A poor man's fix would be to moderately agitate the parts for the first 1 - 2 minutes of the dye immersion to 'rinse' away the acid.

Willie Alexander
- Green Mountain Falls, Colorado


October 26, 2016

thumbs up signThank you for all of your help! We will give this a go, makes total sense.

Chris Jones [returning]
- Coopersburg, Pennsylvania, USA

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