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acetic acid for pH adjustment

I'm curious on what acetic acid [on eBay or Amazon] will do to a black dye bath for controlling ph. My ph meter has been going up and down and I put some acetic acid to lower the pH some, but after I did that my dye is coming out light. Most likely I shouldn't have put any of it in, but my main question is, would putting acidic acid in my dye bath compromise my dye bath? I'm lacking many details I'm sure but any help is appreciated.

Ryan Zettlemoyer
- Melrose, Florida, USA
2006

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First of two simultaneous responses -- 2006

That will depend on which black dye you are using. I used diluted acetic to control pH on our black dye tank.
That said, you have some reason that your pH is going up and down. It should do one or the other, most of the time. You appear to have a drag in problem or are not using the pH meter correctly. pH papers do not work in a black dye tank and organic indicators do not either.
I would reread the instructions for the pH meter and probe, paying particular attention to temperature.

James Watts
- Navarre, Florida

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Second of two simultaneous responses --

Most anodizing dyes call for acetic acid to lower the pH. do it in a bucket first and see what happens. Sounds like your pH meter and standardization is improper. Cheap hand held pH meters are worthless after the first day.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2006

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I use acetic acid as well to adjust my pH in my black dye, Sounds to me that the meter is either bad, weak batteries will commonly make the readings extremely erratic, Probe is bad, or Calibration could be bad.. Change your batteries first, then soak PH probe in 20% HCl (hydrochloric Acid) for 10 minutes. rinse probe thoroughly in DI water until the probe reads nearly neutral. Calibrate the probe according to the manufacturers instructions. and try the Ph read again.

(HCL will get rid of any Metal salts or organics that have built up on the salt bridge of the probe thus "cleaning it" of the contaminants)

Ryan Cook
Toccoa, Georgia
2006

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Ryan,
Try Formic acid (approx. 40% v/v) in a black dye solution. Depending on the solution volume; mix and allow approx. an hour before re-testing.

Joanne Dunford
- Gloucester, UK
2006