• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

Multigrade emulsions

Kirk Keyes said:
Ray - what kind of electrodes are you getting? I've recently bought a digital pH/mV meter and a pH electrode as well. What are you using?
Click to expand...

They are 3 seperate type electrodes, not 2or3 in one.
pH range 0-14
0-100 degree C.
that require a minimimum of 20 mL

Now I am starting to have second thoughts...I wonder if I should have tried something new this time... I don't know... I did pick them up today, but I find I'm still looking at design specs for other models.... Monday I will be hearing from the mfg. anyway maybe I will exchange it...
there are +es and -es to either choice.

How about yours?

Ray
 
Ray -

From my lab experience with everything from very clean waters to really scuzzy samples, I highly recommend Thermo/Orion Ross-type electrodes. They seem to last a long time and are pretty stable. Much more than regular old fashioned general use electrodes I've used in the past. I see Ryuji suggests using Ross electrodes on his web site as well. The Orion 81-02 electrode should be a good one.

Here's a nice guide to Orion Ross electrodes:
Dead Link Removed

That said, as I wanted to stay somewhat on budget, I bought a Mettler INLAB 413 pH triode electrode with a built-in temp probe. Unfortunately, the connector on the Mettler temp does not mate with my Orion meter... But it was only $40 and new in box.

I see right now there is an Orion Ross electrode on ebay:
http://cgi.ebay.com/NEW-THERMO-ORIO...ryZ26230QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Watch out as there is a Ross half-cell and for sale as well, and the person selling the above linked electrode also has an electrode that says Ross in the title, but it is not if you look at the listing... it's an Orion perPhect pH electrode with has an Ag/AgCl junction, not the best for photographic uses, but a good overall electrode for other uses.

Something like this would be a good choice. It's a "heavy duty" model, which one may want if they are not used to handling pH electrodes, or if they are clumbsy...

For people reading this that are looking for bargains, absolutely do not waste your time with a used lab elctrode. All the labs I've been in, when an electrode is going bad or getting old and response is sluggish, they disconnect the electrode, and set it on the counter behind the pH meter. And then is sits there, sometimes for a long time, getting dry and crusty. And not good to use after that. And then there's the ones that have cracks in the sensing bulb. Buy something new when getting a pH electrode.

Also, make sure you get one that is a "combination" electrode. Not a "half-cell" electrode. You want a combination as it has the half-cell reference electrode build into the body of the pH electrode - so it's really two electrode in one housing. You want that. Also, if you can get a temp probe built-in as well, that's really nice. Those electrodes usually have "triode" in the name to let you know that it's got pH, half-cell reference, and temp all in one unit.

What have you been using and what are your looking at?
 
Yeah, it's a nice meter and certainly friendly to the budget, but sometimes it's nice to have something that is more versatile.
 

Kirk,

Since the Ross reference is said to be neither Ag nor Hg based, what is it?

Ray
 
Ray - good question... I don't really know. But the advantage of the Ross design is it's quick response to temperature changes. In the labs I work in, we are calibrating at room temp and then measuring samples that are usually refrigerated, so they are 4-10C. The Ross electrodes give really quick response when switching back and forth from solution to solution. The lack of silver and mercury is an added benefit for our use in photographic applications.
 
You know that two silver electrodes on a multimeter will work, but you have to convert the voltage readings into vAg by doing laborious calculations so that you have a conversion table. So, an off the shelf Radio Shack VOM should work. I have not tried this myself, but a friend has and said it works fine except for the initial calibration and that requires the conversion table preparation.

PE
 
Hello PE,

Do you know where we can find those calculations? It should be possible to input the voltage readings in to a handheld or a laptop and write a small program to make the calculations on the fly, and in so doing, enable us to use more readily available electrodes....

It may not be the cheapest route, but it could be used as part of a process control setup.

Bob M.
 
It must be done from the Nernst equation and the Debye-Huckle equation. You would enter salt concentration and get out the vAg or pAg. Then you compare that to the voltage or resistance on the VOM. Then you plot the voltage against vAg to get a conversion chart. Once the chart is done, you only need it and the VOM apparently. I have not tried it, as I said, but a friend has. Further than that, I can't say until I try it. I have no reason to dobut that it works, and it really should but it would not be as accurate as the system we used at Kodak.

PE
 
rmazzullo said:
It should be possible to input the voltage readings in to a handheld or a laptop and write a small program to make the calculations on the fly, and in so doing, enable us to use more readily available electrodes....
Click to expand...

Bob - I don't think you'll find electrodes that are any more available than ones designed for pH type meters. Electrodes are usually avail with BNC (sometimes called "British Naval Connector", but are actually termed "Bayonette Neil-Concelman") fittings and these will fit nearly any pH meter you can buy made in the last 20 or so years. If you want to use an older meter, you can get BNC adaptors to fit those too.

Also, a lot of these pH meters come with serial connectors, so if you're going to all the effort to input measurements from an electrode into a computer, then running the electrode into the meter and then importing the serial output into a computer will be the quickest and easist way to get this done.
 

This is what a pH meter does... Save yourself some time, unless you REALLY like to DIY it.

And remember, nearly all pH meters also will give results in mV (millivolts) if you can to see the direct output from the electrode. Or if you are using like a redox electrode, you would actually use it in mV mode.
 
Of course Kirk, but most pH meters do not have two silver electrodes, and some do not read in mV. I think, according to my friend, that the glass/silver combination will introduce a bigger bias in the scale. Not sure, as I repeat that I have not personally tried this.

At Kodak we used a very different method to prevent salt contamination and calomel contamination, as well as having a special silver electrode.

PE
 
Kirk Keyes said:
Ray - with all the talk about patents around here, maybe this one will answer it...
Click to expand...

Unfortunately, it doesn't.
Unless I am totally snowblind...

I imagine it IS in one of those patents, just not this one.

Perhaps this is an example of what PE was saying about one real "invention" (my words) or product, being spread out over several "patents"... who knows, but anyhow, this particular patent does not seem to describe the "Ross" reference system.

Ray
 
Lassie Come Home!

Kirk Keyes said:
Ray - good question... I don't really know. But the advantage of the Ross design is it's quick response to temperature changes.
Click to expand...

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 have not made a final decesion yet, but at this point, the Ross line sounds more like a Chiwawa than a German Shepherd to me!

I am more of a Collie man myself.
 
Ray;

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

PE
 

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...
 
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.
 
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
 
Last edited by a moderator:

That IS interesting.
Feed me more!

Ray
 
Ray Rogers said:
That IS interesting.
Feed me more!
Ray
Click to expand...
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:
 
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
 
Kirk Keyes said:
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.
Click to expand...

In that case, there is still hope for them Rozzis!
 
You must log in or register to reply here.
Menu
Log in
Register