Mr. Ellis, and any others who have not tired of this discussion:

Everything you say about the weakness of pH as a measurement of cleaning MAY
be true....HOWEVER...pH will always remain a better instrument of measuring
cleaning power of a used cleaner solution than titration...

Titration measures quantity of alkali, and gives us no measure of type, or
quality...pH is a marker of type, or quality, and a rough measure of quantity...
I remind you of my previous example, that a very old, used cleaner solution
can titrate as full strength, and not be able to clean at all...yet, a properly
made up cleaner solution always cleans with the same activity at the same pH,
thus pH reflects cleaning activity...

Have we beaten this thing into the ground enough?

Rudy Sedlak
RD Chemical Company

In a message dated 9/24/03 8:37:13 AM Pacific Daylight Time,
[log in to unmask] writes:

<< Rudy

 There is no pH endpoint, that is the whole problem. You speak as if a
 saponifier were just an unbuffered solution of MEA. From my experience
 of over 30 years of using buffered commercial saponifiers, I know they
 stop working long before there is a very noticeable drop of pH, and I'm
 quite categorical about that. I know of no MEA- or NaOH-based saponifier
 which will even think about working at pH 9.8 to 10 with an RMA/RA flux
 system. At that pH, you are generating white residues where there is flux.

 Brian

 Rudy Sedlak wrote:
 > When using a saponifier, the available alkalinity is a key part of
 > cleaning, not the "reserve" alkalinity...
 >
 > pH is a measure of available alkalinity...and it is important to
 > remember that since pH is a logarithmic function, a drop of one pH unit
 > means a drop of 90% of available alkalinity....
 >
 > Titration is a measure of reserve alkalinity....which might be of some
 > interest, but not on the next board that goes through the cleaner...
 > Remember, you really will never use all the alkalinity that is titrated,
 > so, if we were going to be completely accurate, we would use a titration
 > controlled by pH, with the endpoint at the lowest acceptable pH for
 > cleaning boards.....if I were using a Monoethanol Amine based system,
 > with a starting pH of 11.3, or so, I would use the system to a pH of 9.8
 > to 10.0.
 >
 > Rudy Sedlak
 > RD Chemical Company---------------------------------------------------

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