setting up a dark room

[oriecat]

It's true!

 

[motcon]

oh, i don't know....informed decisions are always the best. credits for this information are given below.

1. the pH change from developer to stop can generate molecular heat and cause grains in the film to clump.


2. Acid stop baths cause pinholes and reticulation with developers
containing carbonate.


3. Acid stop baths cause excessive swelling which leads to a loss in
image integrity.

‘1. pH variations occur when a film is moved from an alkaline developer into an acid stop bath. This can generate enough molecular heat to cause the grains of the film to clump together.

Haist wrote, 'The use of carbonates in developers may produce blisters in the emulsion layer of the photographic material when this matieral is transferred from the alkaline developer to any [!] acid afterbath, such as an acid stop bath or acid fixing bath. The carbonate still retained in the emulsion layer after development reacts with the acid of the afterbaths to produce carbon dioxide gas bubbles, which may then rupture the gelatin of the emulsion layer.'

‘> stopbaths cause "pinholes"? [or reticulation or other gross image irregularities?]

They can, but this can be avoided, and the power of the stop bath to stop development can be increased by a factor 10 (measured in time) by using a buffered stop bath as suggested in FDC, p. 104. The formula, which is not obvious because it is contained in the text, is

120 ml 28% acetic acid 80 grams sodium acetate to a litre of water

[or an equivalent amount of sodium di-acetate]

That is an expensive stop bath. But it's the best that science offers us. I strongly recommend reading the Crabtree and Henn article on which it is based, which I cited earlier. It is one of the great, finite, experiments in photographic science. Second, I would say that my position is that stop baths may cause harm and can under most circumstances that exist for ordinary photographers, beneficially be avoided. But, equally strongly, I hold that if you are going to use a stop bath, today, it should be an intelligent (albeit expensive) stop bath formulated along the lines suggested by Henn and Crabtree. Otherwise there's little point in using it.

‘We have established that the ordinary dilute acetic acid bath (a) causes unnecessary swelling and (b) does not stop development rapidly. The mechanisms for dealing with this are clearly described in Haist, and partly by me. The relevant pages in Haist are 539 to 557. However, the foundational paper is Henn & Crabtree, PSA J., 17B:14 (1951), which must be read in its entirety to gain a complete understanding of the mechanism of the stop bath.’

‘That is true, and a commonplace. I had an extensive, beautifully researched chapter on stop baths, the first I wrote, and the best loved, that I had to throw out - there wasn't room. I advocated buffered stop baths with additional sulfate to tame swelling. If you look at your Haist carefully, you will see the research which indicates that any ordinarily constituted stop bath does not, in fact, stop development rapidly. Only a buffered stop bath will stop development rapidly.’

'the forces there are so great that of course there is an effect on the silver image. It may be subtle. It may not be so subtle. But it's there. There may be severe reticulation. There may only be very moderate reticulation, not visible as such, which causes a moderate, not fatal, but visible, and measurable, loss of image quality. Now, you can avoid that completely by avoiding the unnecessary use of acid solutions in black and white processing. So why not do it?'

OK. Let’s turn to Ilford's LFA Mason, 1975, p. 207 discussing what occurs when alkaline film is placed in dilute acid baths: 'some movement of the image silver may accompany the mechanical relief pattern. The fine particles of image silver tend to migrate to the edges of the relief pattern ... When this happens, graininess is very much worse than would normally be expected.

‘One of the disadvantages of the carbonated alkalis is their tendency to cause blisters within the gelatin layer as a result of the release of carbon dioxide gas when the alkaline developer is neutralized by the acid fixing bath.' It is because of this practical necessity that Russell invented Kodalk.

credits: Bill Troop, Steve Anchell, Grant Haist - photographic chemists.

also keep in mind that stop bath mixed with certain other standard darkroom chemicals and other agents such as bleach can release cyanide gas.

 

[telex95]

I would also suggest easy access to a sink (water and drain), since u need to wash ur film and paper!

Oh and umm... safety light...!!!

And a good spot to hang ur prints to dry (negatives), if ur not using a dry roller... which i dont recommend... since it can burn mat paper! Well that happened to me... but hey!

Since, the film will be loaded into a light sealed tank, do we really need safelight?

 

[oriecat]

The safelight is for printing, not developing.

 

[Hertz van Rental]

You can get safelights for developing black and white film. They are very dark green. Ansel Adams said he used to use one for developing 'by inspection'. But then he was a bit of a poseur.
I've tried using one and you can see b*gger all - eating carrots works better - so I wouldn't bother.