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pH Measurement

The pH measurement of ceramic powder can be influenced by many factors. Can you advise the best method of measurement for Barium Titanate powders? We use RO (reverse osmosis) water in our pH tests.

Pat K. [last name deleted for privacy by Editor]
FERRO - Niagara Falls, New York
2001

First thing I/we should note is that a powder, or any solid, does not have a pH. You have to make an aqueous solution with water before pH even exists.

I noted that you are using very pure water to create your solution. This type of solution is very similar to the ones I worked with when I did salt spray testing. When you purify water to extremes like using RO, the water very aggressively tries to dissolve things. This water can leach materials out of a stainless steel container. This water can even dissolve carbon dioxide and other substances from air. When water gets very very pure, it is hard to keep it that way. I do not know how susceptible your solution will be to contamination.

You also need to know how accurate of a measurement you require. Obviously, more accuracy is harder and more costly. I suggest you look through a laboratory equipment catalog to see what types of pH measuring devices are out there. You should also call the vendor and talk to a technical salesperson who can advise you on what product will best fit your needs. I would guess that you need a decent pH monitor and probe which would cost at least $500. The really good ones can cost a few thousand. Don't look for a cheap hand-held meter.

Tim Neveau
Rochester Hills, Michigan
2001

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Tim touched on water. It is very difficult to measure a pH in very pure water. If you are actually leaching out ions from the ceramic, then you should not have a problem if you stir very well and do not get in a rush for the reading.

For my nickel, Orion has the most complete research that they will share with customers and potential customers. I would certainly contact their tech services. Scientific supply houses just sell them, so the availability of info from them will be less. Corning and Beckman are a couple of other name brand manufacturers.

James Watts
- Navarre, Florida
2001