Modern Rodinal Substitutes Part II

[Kirk Keyes]

But how much effect would these ancillary compounds really have on the development of films? And in what ways?

 

[Ray Rogers]

Just converting from conductivity to vAg will change the excess halide available to diffuse into the developer at the start of the process.

Modern sensitizing dyes are quite different than the early dyes and we both know that. Examples are modern cyanines and merocyanines and earlier ones include many ortho dyes instead of pan dyes. Erythrosine comes to mind here.

PE

Re Conductivity vs VAg...
For the most part, arn't they both aimed at getting one to the same point?
I thought conductivity was used to estimate the degree of washing...
and infered a certain desired the pX from that.
I had the idea that VAg was just a more accurate measure....
and that the desired point would be the same despite which method was used to get there.

Re Dyes
For the triphenylmethane dyes, etc., yes I agree.
Somehow I thought you were thinking of something newer.

Ray

 

[Photo Engineer]

Ray;

Firstoff, one never measures pX. You cannot infer much of anything from it. You need vAg or pAg to measure the free Silver ion present as it is the critical item and varies with halide. Conductivity is not a measure of either when you get down to it.

As for dyes, sure I can throw in an Osmate dye complex just for fun.

PE

 

[Ray Rogers]

Ray;

Firstoff, one never measures pX. You cannot infer much of anything from it. You need vAg or pAg to measure the free Silver ion present as it is the critical item and varies with halide. Conductivity is not a measure of either when you get down to it.

Well, pAg and pX are related of course...
and while pAg is of interest, is it not the AgX solublity that is really the important consideration when conductivty is being measured, ie just prior to CD?

If so, then the halide concentration should be of interest... in anycase you are right, conductivity is not really a measure of either pAg or pX,
but... they both change with progressive wash efectivness and therefore their former? usefulness as a guide.

---

Re the extra fun Osmate dye complex...
On no, lets wait a while!
I don't want to over dose!

Ray

 

[Kirk Keyes]

Ray - if you've been following along for the last couple years, you would have remembered that pX is useless when there is a mixture of halides in the system. What does that number tell you when there's a mixture?

Thus, pAg is measured instead.

 

[Ray Rogers]

Ray - if you've been following along for the last couple years, you would have remembered that pX is useless when there is a mixture of halides in the system. What does that number tell you when there's a mixture?

Thus, pAg is measured instead.

Yes.
pX is used only as a placeholder...
It indcates only that we could be talking about any halogen,
even mixtures.

 

[Photo Engineer]

Kirk;

Regardless of the halide ratio, the absolute Ag+ in solution is the item of concern. With that in mind, pAg or vAg then becomes the measure of choice. With mixed halides or between Cl/Br/I and mixtures thereof the pX can be just about anything, but equimolar Br and I for example alone will give nearly the same pX or vX, but the vAg or pAg may be different by a huge amount. Therefor it is easier to measure Ag+ with precision by use of the Silver ion in solution regardless of halide type or mix thereof. This then determines excess halide, of whatever type, in the coating at the start of the process, and also helps with keeping.

Of course, I like to prewet which normalizes vAg to be about that supplied by city water which actually seems to do nothing with D-76 or HC-110. Now, I have to try Rodinal.

PE

 

[gainer]

Patrick;

I won't laugh, but one operation I will not do is filter a concentrated KOH solution. Too much chance of an accident, and the KOH usually ends up dissolving the filter paper. The CaCO3 is colloidal and can go through the filter paper.

Best use a sintered filter for this one, if it even works.

PE

Yes, some not only goes through the filter, but very soon clogs it so that not much of anything goes through. I don't try filrering any more. I stir vigorously, let it settle, and stir again. After it settles, I decant most of the clear liquid as slowly as possible so as not to stir up the settlement. It's not the best way to prepare a really concentrated KOH solution, but I think it will be good enough for Rodinal. A gram molecular weight each of Ca(OH)2 and K2CO3 will produce 112 grams of KOH . I don't need more than 30 grams, which should be easilly gotten if I use enough water to make a 30% solution. It's theoretically more wasteful than filtering, but the ingredients are not very expensive and can probably be more easilly bought in some places.

 

[gainer]

P.S.- Any thing that will filter my coffee will surely stand KOH.

 

[gainer]

Have you collected some and done some spot tests to see what it is? Does it burn after drying? What's the pH if you dissolve it in some more water? If you can dissolve some in water, does it form a precipitate with calcium ions?

There are 3 simple tests to get you headed in the right direction for identifying the precipitate.

It does dissolve when I add more water.
My tap water is eminently suited for drinking because of its good taste and calcium content. It forms a precipitate in most developers that contain carbonate. I don't see that with this version of Metolal, but I have been using demineralized water. If I were to substitute an equimolar amount of p-aminophenol and reduce KOH accordingly, I would see no lingering precipitate. I can try that as soon as my shipment of p-aminophenol arrives.
I hate to try filtering the K2SO4 out of the precipitated metol freebase, but if everything else dissolved, that should tell me something. At the moment, I'm also fresh out of Metol.

 

[gainer]

Looking at your photo, it looks like you have more than me!

Some say I have the bulging forehead of a genius. Others say I have a receding hairline. The largest brain recorded is said to have belonged to an imbecile, the smallest to a genius.

When I played the Baroque Oboe with the Governor's Palace Orchestra at Colonial Williamsburg I had the advantage of wearing a wig, so nobody could tell about anything but my music. The oboe has been described as "the ill wind that nobody does good."

 

[Ray Rogers]

Kirk,

Somewhere, you described for Bill the calculation of pH of... (I think)
a KOH solution.

Do you know where it is?

My searches are mute...

Ray

 

[BobNewYork]

The oboe has been described as "the ill wind that nobody does good."

Just had to say that I LOVE that quote!!

Following this thread with rapt interest - but nothing to add 'cos it's way over my head. Have a son whose just started his doctoral programme in Chem. Maybe he can explain (some of) it to me!!!


Bob H

 

[Kirk Keyes]

Kirk,

Somewhere, you described for Bill the calculation of pH of... (I think)
a KOH solution.

Do you know where it is?

My searches are mute...

Ray

Ray - that's near the end of Part I of the original thread that spawned this thread. There's a link near the beginning of this thread that links to the first part. Then it's on the last page or two.

 

[Ray Rogers]

Ray - that's near the end of Part I of the original thread that spawned this thread. There's a link near the beginning of this thread that links to the first part. Then it's on the last page or two.

Thanks found it.
Unfortunately, I replied there, somewhat akwardly too.
It should have been here but I am confused with the two threads...

Respond where ever seems most .....

Ray

 

[Kirk Keyes]

Please respond here! The other thread is harder to find!

 

[Kirk Keyes]

Kirk,
How can I Calculate -log10 [whatever] on line?
I no longer have a scientific calculator...

Thanks

Ray
---------
ps, Sorry for the location of ths post... it should be in part 2 very confused... sorry ...

Ray - I would go to http://download.openoffice.org/ and download OpenOffice. It has an spreadsheet program like Excel called "Calc" along with other MS Office like programs. If you can't afford or don't want to spend the money on MS OFfice, then OpenOffice from Sun is a great alternative.

Then you can calculate negative logs to your heart's content!

Also, if you're a Windows person, search around for Microsoft's scientific calculator for windows - under accessories under programs under the start button. It has a scientific mode. I'm sure Mac/linux has something you can download as well.

 

[Ray Rogers]

Ray - I would go to http://download.openoffice.org/ and download OpenOffice. It has an spreadsheet program like Excel called "Calc" along with other MS Office like programs. If you can't afford or don't want to spend the money on MS OFfice, then OpenOffice from Sun is a great alternative.

Then you can calculate negative logs to your heart's content!

Also, if you're a Windows person, search around for Microsoft's scientific calculator for windows - under accessories under programs under the start button. It has a scientific mode. I'm sure Mac/linux has something you can download as well.

I have office on an OLD old mac...
Open Office is on this computer I am using now...
but I have not really used it.

The MS scientific calculator you are talkng about...
is that a freeware or payware item?

Ray

 

[BradS]

even easier...try numcalc

http://www.numcalc.com/

There's nothing to download. it is a website that acts like a scientific calculator.

 

[Dave Pritchard]

I have office on an OLD old mac...
Open Office is on this computer I am using now...
but I have not really used it.

The MS scientific calculator you are talkng about...
is that a freeware or payware item?

Ray

It's the normal Windows calculator. Look for a menu pick to switch between normal mode and scientific mode.

 

[Ray Rogers]

It's the normal Windows calculator. Look for a menu pick to switch between normal mode and scientific mode.

You mean that button that says "log" ?



Problem solved!

I must have been thinking about antilogs or something...
I remember not being able to do it quite so easily....

Ray

 

[gainer]

-log(x) = log(1/x).
I have a TI-30XIIS pocket calculator that does log and trig functions and a lot more. It cost less than $30 and can be found at stationery and office supply places, Rite Aid pharmacies and ordered over the internet. It gets power from light. If there's enough light to see it, it runs.

 

[Ray Rogers]

It gets power from light. If there's enough light to see it, it runs.

I used to have 3 calculators I used in my DarkLab... one was solar powered but it lost data unless I was quite close to a safelight...


My old programable calculator did not read properly unless you squezed it in just the right spot. Missing decimals were always fun...
but i just couldn't throw it away.


I guess I do need a good new one!

The last couple were bought from 1$ stores; and they don't come with a whole lot of skills!


ray

 

[Kirk Keyes]

but i just couldn't throw it away.

I have a Rockwell scientific that I got in 1977 in jr. high school. I replaced it with a Texas Instruments TI-58 programmable in high school, which I replaced with the first graphing calculator (a Sharp) in 1987 when I started working in a laboratory. Then I got a TI-82 about 1995, and it's had some hard lab working since then. It's starting to get some stuck pixels, which sucks as it affects all the digits on a particular line.

So I'm thinking of getting a new one too... But I have all of the old ones still!

 

[gainer]

Does anyone know if, and if so where, I can buy the n-methyl paraminophenol base of Metol without the H2SO4 tail?