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Photo Engineer
04-29-2008, 10:00 AM
Ray;

Kodak patents on their electrode setup and the calculations are few and far between, but there are literally dozens of them.

PE

Kirk Keyes
04-29-2008, 11:30 AM
I read the Owners manual... The fact that they say you have to insulate the sample from the stirrer with styrofoam(?) sort of bothers me...

While I DO wonder if it is really so sensitive (do you insulate like this in your own professional work?), either way, in some situations, high sensitivity could be another way of saying "less robust"....

I am more of a Collie man myself.

Ray -

In the 4 environmental labs I've worked in, we've never insulated the stirrer. Unless you happen to have a stir plate that gets really warm, I don't think it's an issue. Also, we've always used a large enough volume of solution being tested for pH that it really shouldn't change temp very much in the time it takes to make the measurement. 30 to 60 seconds is really all you generally need to make a measurement, and with say 100 mls sample, it's not going to transfer much heat.

I just looked through the owners manual, and I noticed another reason that a Ross electrode would be good for emulsion work is that is says when using solutions that may precipitate with chlorides, you can replace the internal filling solution, which is typically 3M KCl, with 10% KNO3. That will prevent silver chloride from precipitating in the electrode junction and it should lengthen the life of the electrode. You can't do that with a regular Ag/AgCl electrode.

Also, for life of the electrode, when the calibration slope gets down to about 92% or less, then you should think about replacing it. It will be pretty slow in response as well, and you'll get tired of standing around waiting for the measurements to stabilize...

Kirk Keyes
04-29-2008, 11:32 AM
Oh, and it's definitely a Collie. A good, hard working little doggie of an electrode. You can almost see it rounding up all those little hydrogen ions and herding them in to get counted.

Ian Grant
04-29-2008, 11:48 AM
Does anyone know what the nature of co-operation was between Dupont and Ilford before and during WWII ? So while Ilford were forced to delay launching full scale production of Multigrade Dupont were able to produce Varigram (under license from Ilford)

It's interesting that Renwick, worked for Ilford for 24 years before spending 3 years at Dupont (1922-25) in the USA, then returning to become head of research at Ilford in 1925.

Ian

Ray Rogers
04-29-2008, 03:09 PM
Does anyone know what the nature of co-operation was between Dupont and Ilford before and during WWII ? So while Ilford were forced to delay launching full scale production Multigrade Dupont were able to produce Varigram (under license from Ilford)

It's interesting that Renwick, worked for Ilford for 24 years before spending 3 years at Dupont (1922-25) in the USA, then retuning to become head of research at Ilford in 1925.

Ian

That IS interesting.
Feed me more!

Ray

Ian Grant
04-29-2008, 03:29 PM
That IS interesting.
Feed me more!
Ray
Ray, I don't know more, that's why I'm asking.

All I know is that Dupont Varigram was based on licensed Ilford technology, then I happened to remember reading Renwick spent 3 years in the research department at Dupont. Perhaps there was some joint research.

It would be interesting to find out.

Ian

Ray Rogers
04-29-2008, 03:30 PM
[QUOTE=Kirk Keyes;623701]Ray -

In the 4 environmental labs I've worked in, we've never insulated the stirrer.
Ah Ha! As I suspected... you have been ignoring the mfg instructiions... tsk tsk tsk- shame on you!:o

I noticed another reason that a Ross electrode would be good... you can replace the internal filling solution...with 10% KNO3....You can't do that with a regular Ag/AgCl electrode.
Yes- thats clear. But that ability is not unique to Ross electrodes.
Both of mine do this nicely!

Ray

Ray Rogers
04-29-2008, 03:41 PM
Ray, I don't know more, that's why I'm asking.

All I know is that Dupont Varigram was based on licensed Ilford technology, then I happened to remember reading Renwick spent 3 years in the research department at Dupont. Perhaps there was some joint research.

It would be interesting to find out.

Ian

Do you remember where Dupont was at that time?
NJ? Rochester?

I seem to recall PE mentioning something about a Kodak relationship too, but not in this exact context....

:confused:

Photo Engineer
04-29-2008, 03:50 PM
Kodak had no relationship with Dupont AFAIK, but the Dupont film and paper division (at least in part) was in Rochester on Driving Park Ave., walking distance from Kodak Park. It is now an empty lot. Many Kodak people moved to Dupont at one time I have heard.

Dynachrome was a short block west of the Dupont plant near Mt. Read Blvd, where they made and processed Dynachrome film. These employees too were mainly former Kodak people I was told.

Across Mt Read Blvd from Driving Park was the 3M plant where they made graphic arts films. Color and other R&D were done at 3M HQ or at Ferrania in Italy. I don't believe that they had many former Kodak people. They also had another plant somewhere in the surrounding area.

There you have all I know about interconnections.

PE

Ray Rogers
04-29-2008, 03:50 PM
Oh, and it's definitely a Collie. A good, hard working little doggie of an electrode. You can almost see it rounding up all those little hydrogen ions and herding them in to get counted.

In that case, there is still hope for them Rozzis!:)

Ian Grant
04-29-2008, 03:56 PM
Did Dupont sell off their Photographic division, Dupont specialised in cellulose and then polymers. So was Renwick working on film base materials.

A German part of Dupont became Adox, which was later sold to EFKE.

Ian

Photo Engineer
04-29-2008, 04:00 PM
Ian;

The Dupont plant here operated under that name until it closed. It was near our apartment years ago, and later I drove by on my way to the camera store which was about 2 blocks from the Dupont plant. When it closed, all buildings were torn down.

EFKE occupies an old Kodak plant and uses old Kodak equipment I was told. This comes from someone who was there and who talked to employees about their history. If this is wrong, I would like correction on this.

PE

Ian Grant
04-29-2008, 04:10 PM
Forte occupied the old Kodak plant in Hungary. The Adox formulae & machinery were sold to EFKE and shipped to Croatia from Germany in the 50's.

Ron are you implying some cross reference between Dupont & 3M/Ferrania ? Did Dupont sell their photographic division to 3M ? or perhaps just the coating plants ?

Ian

Photo Engineer
04-29-2008, 04:16 PM
Ian;

Thanks for the information.

No, there was no connection between Dupont and 3M AFAIK except their being located less than 1 KM apart here in Rochester. They may have had employess from one join the other etc.. but IDK.

PE

Ray Rogers
04-29-2008, 04:38 PM
Which rings me back to the post I deleted thinking it was off topic... Why were several/so many similar companies comming to sit on the doorstep of Kodak?

If not for Technology, if not for People, and if not to be absorbed, What then was calling them to Rochester? The weather?

Ian Grant
04-29-2008, 04:50 PM
It has to be a pool of technicians, specialising in setting up coating machines, optical manufacture etc. Perhaps a machinery manufacturer.

All my books, or rather 98%+, are European, I can't see any reference to Dupont manufactured films or paper other than the Adox brand of films in Germany, which by 1954 were made under license from Dupont by Schleussuer. Certainly no mention of film or paper in the US after WWII

As I said earlier Dupont were specialists in Cellulose & Polymers, did they make film base ? Did they make the base materials for 3M.

3M were not involved in the graphics/photography market until they made acquisitions in the 40's. They made their millions inventing Sellotape & masking tape as well as "wet & dry" sand paper.

There is something going on in Rochester and major changes after WWII.

Ian

Kirk Keyes
04-29-2008, 04:57 PM
Why are all the tech companies in San Jose? You get confluences of technologies in certain geographic areas for multiple reasons, like there's a trained workforce - or even the weather!

Remember that Cincinnatti was once the meat packing capitol of the world for a number of reasons, like transporation, supply, and actually, weather.

Ian Grant
04-29-2008, 05:01 PM
And Detroit once made cars :D

Ian

Photo Engineer
04-29-2008, 05:40 PM
Well, there were the engravers that made equipment for embossing photo and film products, there were chemical industries here, there was the pool of technicians who might not want to move home and family if they changed company and there was also Haloid/Xerox and Bausch and Lomb here. There were a lot of printing companies here that produced packaging for both Kodak and Xerox. Rochester is also the headquarters of Gannett Publishing who use a lot of Graphic Arts materials.

Dupont did make Varigam and Varilour papers up until they left the photo field. Haloid made RC papers here and VC papers as well. We used a lot of the Haloid and Dupont products in the military.

Dupont made a complete line of oscillographic recording processors and papers that were gradually replaced by Kodak products at the cape when Kodak begain producing the Ektaline products.

PE

Ian Grant
04-29-2008, 06:17 PM
Ron, did 3M's rise (in the photo field) coincide with the loss of the Dupont brand names. Can you put a rough date on Dupont leaving the photo field. 3M's website indicates they became involved with photography in the early 60's.

Some thing else is coming back to me about Ilford & Dupont, I need to find something I read a year or two ago.

Ian