To pre-wash or not to pre-wash?

[mshchem]

Do we have any polite comments about prewetting and 2-baths? My thought is to reduce the accumulation of dyes and iodides in the first bath.
Naturally the first bath would have to be extended abd vigourous.

AgI is insoluble in water so it along with other silver halides will stay in the gelatin.

 

[Murray Kelly]

mshchem, we agree. But what about the KI and whatever light sensitivity curve altering chems?

To be specific my interest is the degrading of Dignan's 2-bath C-41 developer which is almost universally extolled then, a few films later, deemed not so good after all.
Would a prewash help, maybe?

I point out that most of what is in the last B&W sticky covers the ground here. PE, on questioning, said he used a prewash for everything.

 

[mshchem]

mshchem, we agree. But what about the KI and whatever light sensitivity curve altering chems?

To be specific my interest is the degrading of Dignan's 2-bath C-41 developer which is almost universally extolled then, a few films later, deemed not so good after all.
Would a prewash help, maybe?

I point out that most of what is in the last B&W sticky covers the ground here. PE, on questioning, said he used a prewash for everything.

The KI should be washed out along with the nitrates during the washing of the emulsion prior to coating. Correct??

 

[Sirius Glass]

Three minutes of continuous agitation for me.

As part of a consistent, repeatable process which provides results that satisfy my needs.
I always work at room temperature, including using room temperature pre-rinse.
I also think the colours are pretty.

I have found that pre-washing color and black & white film has reduced the chances of uneven development. I use three minutes of the Jobo processor. The only exception is that I do not pre-wash Kodak Tri-X film when developing in XTOL [stock or replenished] based of John Tinsley's research and discussion in his book.

 

[Philippe-Georges]

I have never seen a commercial film processing machine that pre-wets the film. In a commercial lab, time is money, so why pre-wet when it is not necessary.
Maybe where a lab uses a non-automated process, rotary tank, small tank etc, they may see the need for a pre-wet, but in all my years processing commercially and talking and visiting other labs, big and small, professional and amateur, I never saw a pre-wet/pre-wash used.

As an analogy, it remind me of the argument about cooking pasta. One says to use a big pot with plenty of water. The other says that a drop of oil into the water in the pot will stop the pasta from sticking.

Discuss.................

One may not forget that in commercial (professional-) labs the processing is done with nitrogen gas agitation, which is absolutely completely different than hand- or rotation agitation. These gas bursts are chasing air bulbs and, if I am not mistaking this gas is warmed up at processing temperature (REFREMA machine).
Also in these DIP&DUNK machines, the film is HANGING vertically with a wight at the end, so the liquids are freely moving around the filmstrips, no spirals where the film is wrapped around with such a small diameter according the tank.

Never compare professional lab processing with DIY home developing.

BTW the film 'spirals' in my Colenta (home-) developing machine had a diameter of about 30cm, a 120 roll film could be wrapped around, emulsion outside, in ONE turn (not overlapping), that's why they were called 'baskets' instead of spiral's! The agitation was alternating rotation and I could process 10 120 roll films in one run and 2,7 liters where needed per bath.
In the Colenta, pre-wetting was mandatory for B&W REVERSAL processing (AGFA SCALA)!

 

[Raghu Kuvempunagar]

In the Colenta, pre-wetting was mandatory for B&W REVERSAL processing (AGFA SCALA)!

Philippe: if it's not a problem, can I get more details of your method for reversal processing including the first developer? I believe you use homebrew chemicals for reversal. I can start a private conversation if you prefer that route.

 

[MattKing]

One may not forget that in commercial (professional-) labs the processing is done with nitrogen gas agitation, which is absolutely completely different than hand- or rotation agitation.

I would hazard a guess that most commercial processers now are roller processors.
A few dip and dunk lines remain, and they should be supported, but they require high volumes to make sense.

 

[Murray Kelly]

The KI should be washed out along with the nitrates during the washing of the emulsion prior to coating. Correct??

I have to say I cannot see why there is KI and KNO3 applied before the emulsion, only to wash it off before that step in manufacture. IDNK how or why it would be done. Sorry.

 

[Philippe-Georges]

I would hazard a guess that most commercial processers now are roller processors.
A few dip and dunk lines remain, and they should be supported, but they require high volumes to make sense.

Yes, indeed, flow processors, where the film isn't wrapped on a spiral but pulled in it's full lengt over rollers, zig-zag thru the chemicals, which again is different.
These chemicals are 'agitated' with a kind of slow working circulation pump system.

 

[Tom Kershaw]

BTW the film 'spirals' in my Colenta (home-) developing machine had a diameter of about 30cm, a 120 roll film could be wrapped around, emulsion outside, in ONE turn (not overlapping), that's why they were called 'baskets' instead of spiral's! The agitation was alternating rotation and I could process 10 120 roll films in one run and 2,7 liters where needed per bath.

Are you still using the Colenta?

 

[Philippe-Georges]

Are you still using the Colenta?

No, as a matter of fact, I am thinking of selling this Rolls-Royce of the small professional developing machines.
It can develop all kinds of formats, ranging from 35mm rolls till 24x30cm sheets, in all possible processes imaginable due to an easy to program built in microprocessor.
The Austrian manufacturer still exists...

 

[foc]

I would hazard a guess that most commercial processers now are roller processors.
A few dip and dunk lines remain, and they should be supported, but they require high volumes to make sense.

Dip & dunk are great processors and produce excellent results in the right hands, but they need a lot of space to operate. They must be in a darkroom, usually with the replenishment unit, nitrogen gas tank, and sometimes the storage tanks. The only part that is, usually in daylight, is the dryer exit door (if the machine has a light trap dryer)

Minilab type processors, leader card type, are very compact and have a very small footprint. They can be operated in daylight, all you need is a dark box (like a changing bag but as the name suggests it's a box with the arms of a changing bag) to load the dark cassettes with 120 film. 35mm film (unless damaged) can be loaded from its cassette, spliced to the leader card. In these processors, the only part of the film touching the machine racks is the film edge.

If a lab is operating in a retail unit, then space is money. Every meter of a retail unit must pay its way, so I don't think a dip & dunk processing machine would be economical.

Regardless of the processing machine type, if it is used and maintained correctly, then it will produce excellent results.

my Colenta (home-) developing machine had a diameter of about 30cm, a 120 roll film could be wrapped around, emulsion outside, in ONE turn (not overlapping),

Delighted to hear about your Colenta. The only problem I found with them was if a clip was dislodged during the process it could catch in the drain trap and keep it open and so the next bath would just drain out. Other than that they were a great machine for their time.

 

[Tom Kershaw]

No, as a matter of fact, I am thinking of selling this Rolls-Royce of the small professional developing machines.

Is there any information on these machines online?

 

[removedacct2]

I would hazard a guess that most commercial processers now are roller processors.
A few dip and dunk lines remain, and they should be supported, but they require high volumes to make sense.

the few independent shops doing film development are still C41 based, and C41 requires preheating one way or another, so whatever method they must have a way to do this.

Some other businesses offering film development do send elsewhere where bigger amounts are processed. For instance here in Norway we have a Japanphoto chain , which is just the local flavor of the german CEWE group, but population is very little here, so If you bring film to Japanphoto, it is send for processing to Germany or Danmark to some large scale processing facility.

 

[Philippe-Georges]

In the more than 25 years I worked with this machine, I only got this clip problem only once. Then I bought an Infra Red viewer, a used one from the AGFA-Gevaert factory in Mortsel-Antwerp. So I could interfere when this incident happend again, luckily it wasn't necessarily.
But that viewer was very useful anyway.

Is there any information on these machines online?

hardly...

 

[mshchem]

One may not forget that in commercial (professional-) labs the processing is done with nitrogen gas agitation, which is absolutely completely different than hand- or rotation agitation. These gas bursts are chasing air bulbs and, if I am not mistaking this gas is warmed up at processing temperature (REFREMA machine).
Also in these DIP&DUNK machines, the film is HANGING vertically with a wight at the end, so the liquids are freely moving around the filmstrips, no spirals where the film is wrapped around with such a small diameter according the tank.

Never compare professional lab processing with DIY home developing.

BTW the film 'spirals' in my Colenta (home-) developing machine had a diameter of about 30cm, a 120 roll film could be wrapped around, emulsion outside, in ONE turn (not overlapping), that's why they were called 'baskets' instead of spiral's! The agitation was alternating rotation and I could process 10 120 roll films in one run and 2,7 liters where needed per bath.
In the Colenta, pre-wetting was mandatory for B&W REVERSAL processing (AGFA SCALA)!

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Very nice outfit! Perfect.