I have been searching for a used RA-4 processor like Colenta Studio Line or similar for some time, and was today offered an old Beka with 24" width.
The machine is originally designed for B&W, but has both speed and temp adjustments.
How tolerant is RA-4 for modifications, eg, lower temp and slower speed?
Thank's for any input, Jan, Finland.
You can get room temp chemicals but they cost more. Don't all the processes go to completion?
"Don't all the processes go to completion?"
Nick, not in my lifetime. The more I do digital output, the more I value the analog methods.
Sitting the whole day by the computer necessary gives me nothing, but one hour in the darkroom, and I will sure have something to show.
Now, I'm searching practical information about the standard RA-4 process, not about those hobby kits.
There must be a lot of people on this forum that have run RA-4 outside the norms.
There are a number of slightly different RA-4 processes, for different types of machines. One of them might work for you. For example, our machine at work runs at 95F and a has a 45 second development time. Try talking to Kodak- there are still experts there.
Jan
yes you can modify time and temp for RA 4, this goes all the way back to the days when RA 4 was introduced and many EP 2 machines were converted to the new process. Many of those old machines weren't capable of running the new times and temps so Kodak and the others brought out modified RA 4 for their machines.
I have one of these old machines and have tried the current RA 4 as low as 30 degrees with no problems. Also run it at 35 degrees and appears to be no difference. This is a high volume processor and I use lab kits, not the home process kits.
Your main concern with a converted B&W machine is adequate wash at the right temp, B&W requires substantially less.
Clayton
Thank's Clay!
This is the information I was after. I suspected that RA-4 was not prone to crossovers,
and now this seems to be true. One question still; what time do you use with 30 Cdegrees ?
1,30" perhaps? As the process goes slower, the constants holds better I think. And the machine life is also extended.
Jan
Jan
I've dug out some old Kodak papers for RA4 conversion for machines not designed for it, the process used is called RA 4ECM.
Time and temp as follows
45s = 35 degrees
1.00 = 32.8
1.15 = 31.4
1.30 = 30.0
1.40 = 29.4
Over 1.40 use adjustment correction factors which appear to be colour filtration changes on the enlarger. These are read on control strips from a densitometer......better not to go that way and complicate things. You'll find once you experiment a little and get it right it'll hold as long as you don't replenish and dump the chemicals after your run is done. If there's still some life in the chems bottle it and reuse, I do that all the time with no probs.
Something many people don't realise, conventional colour printing can be very cheap and productive with the right equipment. Sure beats staring at a monitor all day long.
Clayton
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