B/W reversal: emulsion as soft as marmelade

[Hans Borjes]

From the results with the Kodak b/w reversal kit I have stopped using TMAX for the moment because FP4 gives the results in the projector I was looking for.

However, FP4's emulsion gets extremely soft during this process, as opposed to TMAX. I am seeking for ways to improve this.

I have noticed that small pieces of the emulsion are already coming out of my Jobo CPE2 beginning with drain of the fixing bath. Looking at the description of the MACO LP Fix Supra, it says this acidic chemistry is powerful and especially dedicated to TMAX films.

I have read somewhere that differences in pH value between baths are causing the emulsion to soften.

Additionally I found that there is a MACO LP Fix Neutral which has a neutral pH value and is dedicated to baryte papers.

Has someone made experiences using neutral fixers and possible hardening additives in reversal processing of traditional emulsions?

The FP4 gets so soft at 24°C that it is impossible to remove it from the reel without shifting parts of the emulsion into the actual image area...

 

[Tom A]

I have had the same problem with efke (adox) 25 and ilfords reversal proces, very soft emulsion. I solved the problem with a hardening-bath after the first developing, 2 minuts in tetenal hardner at working strength and the rest of the reversal proces as normal. Sometimes I also add some hardner to the fixer, but I'm not consistent doing that.

Tom

 

[Jordan]

Hopefully Alessandro Serrao will chime in on this thread. In short, I've had the same results as you. My problems were solved by switching from a permanganate-based bleach (such as the one in the Kodak kit) to one based on dichromate. The relative merits of these types of bleach have been discussed extensively in other threads on APUG so I won't get into them here.

Dichromate has a hardening effect, just like Tom's Tetenal hardener.

Alessandro has found that he can eliminate emulsion damage during reversal processing by being absolutely scrupulous about keeping the temperature of his process constant.

 

[fschifano]

Are you using a hardening fixer? I believe that it is recommended with the Ilford and any other B&W reversal process.

Neutral or alkaline fixers cannot by definition be hardening fixers. The alum used as a gelatine hardener requires at least a slightly acidic environment to work.

 

[Hans Borjes]

I solved the problem with a hardening-bath after the first developing, 2 minuts in tetenal hardner at working strength and the rest of the reversal proces as normal.

That seems to be easy. I am trying to get the 6-slot extension for my CPE2-Plus, but so far I am using 7 bottles already with 4 slots only. It would be difficult to add another bath.

My problems were solved by switching from a permanganate-based bleach (such as the one in the Kodak kit) to one based on dichromate.?

Do you know which kind of bleach is in the Foma kit? I have also thought about switching to that one for a 100% neutral image tone which doesn't seem to be possible with the Kodak kit.

Alessandro {Serrao} has found that he can eliminate emulsion damage during reversal processing by being absolutely scrupulous about keeping the temperature of his process constant.

This seems to be somewhat easy to achieve in my environment. In my current process I fill the Jobo with cold water and heat it up to 24°C, a 10 liter bucket with water is taken from the flow heater at 30°C which cools down while the Jobo heats-up and I prepare the bleach.

I would only need to use an aquarium heater to prepare the rinse water.

Are you using a hardening fixer?

I am no longer convinced about that. I asked for it when I bought it. I found a web page that says, the MACO LP Fix Supra contains ammonium thiosulfate and MACO LP FIX RAPID HARDENER for films should be added to the fixer to prevent emulsion dissolving in machine processing.

 

[dancqu]

[QUOTES=Hans Borjes]

"Looking at the description of the MACO LP Fix Supra,
it says this acidic chemistry is powerful and especially
dedicated to TMAX films."

I'd say they don't know beans.

"I have read somewhere that differences in pH value
between baths are causing the emulsion to soften."

There is no doubt that bath to bath changes in ph
do stress the emulsion. At higher temperatures the
emulsion is more vulnerable.

"Additionally I found that there is a MACO LP Fix
Neutral which has a neutral pH value and is
dedicated to baryte papers."

A neutral fix dedicated to BARYTA PAPERS.
That's really choice. They'll not top themselves
with that one.

"Has someone made experiences using neutral fixers ..."

I have. A dilute sodium thiosulfate will run just shy
of ph 7 and a dilute ammonium thiosulfate fix will run
ph 7.5. I use unadulterated very dilute one-shot fix.

"The FP4 gets so soft at 24°C ..."

That is not so much of an out of the ordinary
processing temperature. Dan

 

[Gerald Koch]

Try using Kodak SB-3 Hardening Stopbath in the formulas secttion.

 

[laser]

DICHROMATE is very bad for the environment... and humans

You should be aware that Potassium Dichromate is a CARCINOGEN. See: www.state.nj.us/health/eoh/rtkweb/1564.pdf


If you have any concern for the environment you should be very careful with DICHROMATE bleaches. If you must use it do not sewer it nor put into a septic system. It should be treated as hazardous waste. Most local governments have hazardous waste disposal facilites you can use. Check with your local authorities.

 

[Jordan]

Dichromate is certainly far more toxic by ingestion than permanganate -- in practice, I find dichromate safer to use, as the bleach itself is stable (permanganate must be acidified just before use) and can be re-used until exhausted (permanganate goes off within a few hours and must be used one-shot).

 

[Hans Borjes]

Thanks everyone for your help. I have added Tetenal Hardener to the MACO LP Fix Supra and controlled the temperature of the rinse water to be the same as the temperature in the Jobo, that improved a lot.