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Testing bath solutions for acid concentrations and mineral deposits

2004

To the experts,

I am in the market for some testing equipment. I would like the experts to advise me according to their personal experiences.

1. I am looking for an accurate way of testing the acid concentrations in different anodizing bath tanks. Of course I'll be working with sulfuric, nitric, phosphoric and chromic acids. My gut feeling tells me that the pros are going to advise titration. I have nothing against titration at all but I am curious to know how the pros feel about hand held meters. Their simplicity and speed are appealing to me.

2. I wish to test my sulfuric acid electrolyte solution for aluminum deposits. What do the experts advise a person to do in this case?

3. To test rinse waters (DI) for contamination on an anodizing line, would the pros advise towards the use of a TDS tester or something else?

Thank you for your advice in advance.

Daniel DeGueldre
anodizing shop entrepreneur - Ste. Anne, Manitoba, Canada

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2004

No responses? I'm really lost when it comes to analyzing my bath solutions and would greatly appreciate some guidance. Because I am really new to this and have so much yet to learn, how about I rephrase the entire question above. How's this :

On a sulfuric acid type II anodizing line consisting of the following stations :

(1) - Cleaner & Degreaser station
(2) - Rinse Water station (distilled H20 @ 68F)
(3) - Etching station (sodium hydroxide

 [affil links] & distilled H20 @ 110 °F)
(4) - Bright Dip station (phosphoric,nitric acid & distilled H20 @ 200 °F)
(5) - Desmutting station (nitric acid & distilled H20)
(6) - Rinse Water station (distilled H20 @ 68 °F)
(7) - Electrolyte station (sulfuric acid & distilled H20 @ 70 °F)
(8) - Rinse Water station (distilled H20 @ 68 °F)
(9) - Dye station (brand name dyes, organic, light fast @ 160 °F
(10) - Rinse Water station (distilled H20 @ 68 °F)
(11) - Sealing station (nickel acetate & distilled H20 @ 205 °F)
(12) - Rinse Water station (distilled H20 @ 175 °F)
 

What criteria would I want to test for in each station and how would I go about it effectively? I would like to know what would be the best methods used in a lab setting then the best methods used in a production line setting.

Thanks so much for the responses...

Daniel DeGueldre
anodizing shop entrepreneur - Ste. Anne, Manitoba, Canada

Titration will work for your needs. I used several analytical books, but the easiest and most straight forward one is in the Metal Finishing Guide Book which comes with a subscription of the Metal Finishing magazine. If you are going to be in the metal finishing field, this book is invaluable. The magazine is not shabby either. The price is reasonable if you have looked at the price of books recently.

James Watts
- Navarre, Florida
2004

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2004

Okay, I'll give it a try:

You didn't say what kind of cleaner/deoxidizer you're using. If it's proprietary, go with the vendor's recommendation.

Stations 3, 5, and 7: Go with an acid/base titration. They're easy and accurate. If your operators are halfway decent, you can even train them to do them.

Station 9: You need to go with the vendor's recommendation; organic analysis is frequently not simple.

Station 11: Again, a titration, but this time it's not a simple acid/base titration. There are fairly simple titrations for nickel, maybe use one of those (easily found in the literature and I'm too lazy right now to dig one up).

Rinse water: You can get conductivity monitors for rinse tanks which will even trigger water additions using a solenoid when the conductivity is too high.

I wouldn't recommend a meter in place of the above titrations, they won't buy you any improved process control.

James Totter, CEF
- Tallahassee, Florida

Do you have a specific chemical supplier, such as Macdermid or Enthone? They should be able to supply you with some invaluable information on the best methods for determining bath concentrations.

John Forbus
finishing industry - Flint, Michigan
2006