Ra-4 development

[DREW WILEY]

I use a paper punch to make little 1/4 inch diameter dots of glow tape for a few timer buttons or light switches, but never in close proximity to film or paper. I too discovered that this is capable of fogging things.

 

[Photo Engineer]

It matters more where the light is in the spectrum rather than intensity, I guess.

PE

 

[John51]

I'm guessing that orange in this range of glow paint would be the best?

https://www.glow.co.uk/glow-paint-30ml.html

 

[Rudeofus]

If you look at spectral sensitivity of a typical RA-4 paper, its sensitivity gap is very narrow. Sadly, the page you linked to does not mention light spectrum emitted by their paints. To give you some illustration what to look for: the original RA-4 light sensitivity gap was aimed at low pressure sodium vapor lamps, which emit light in a very narrow band at 589 nm.

 

[DREW WILEY]

Fuji - probably the main supplier of chromogenic paper for most of us - cautions against even sodium vapor. Of course, that generic caution might be due to the fact they can't control all the variables potentially involved. But I'm not going to go out and spend a lot of money on a new sodium vapor light unless I'm certain it would be safe, and there's no way to find that out without owning and testing it. Old used units are even more problematic. But I'm well accustomed to navigating around my darkrooms (yes, plural) in total darkness.

 

[MattKing]

I'm guessing that orange in this range of glow paint would be the best?

https://www.glow.co.uk/glow-paint-30ml.html

For black and white, maybe.
For colour, green has the advantage that our eyes are most sensitive to it, so you can use less.

 

[John51]

That's a good point. The site says that green and aqua is the brightest.

 

[Rudeofus]

Fuji - probably the main supplier of chromogenic paper for most of us - cautions against even sodium vapor. Of course, that generic caution might be due to the fact they can't control all the variables potentially involved. But I'm not going to go out and spend a lot of money on a new sodium vapor light unless I'm certain it would be safe, and there's no way to find that out without owning and testing it. Old used units are even more problematic.

If you look at the spectral sensitivity curve I linked to, these curves are linear in the y-axis. Which means, that even if these curves seemingly drop down like a rock around 589nm wavelength, paper will still be quite sensitive there (5-10% of max red sensitivity! ). I have used such a sodium vapor lamp with success for RA-4, but I dimmed it down far enough that I just barely got an impression of what was around me. This was nothing like regular red safe light for B&W processing.

At this point in time I would not invest in a sodium vapor lamp, because LED lights are much cheaper and easier to control, and they have no warmup time. My sodium vapor lamp needs 5+ minutes to reach full light output.

 

[koraks]

Concerning leds I do have some doubts concerning spectral purity. For regular (red) safelighting I find that additional filters are necessary to keep fogging at an acceptable level. I haven't tried them for RA4 but I suspect some thorough attention to Led selection and testing with additional filtering are necessary to reach a workable setup.

 

[John51]

Both my amber and red leds show green on the cd test.

 

[DREW WILEY]

I discovered that red LED's on my enlarger control panels, even on the lowest brightness setting, are capable of fogging film. I haven't had a problem with paper yet. So I taped three layers of neutral density lighting gels over them to dramatically reduce the effect even more, and this is in a room painted black with almost no reflections. Furthermore, they're on a shelf angled away from my black film work countertop, on the other side of the room. I'm accustomed to working in total darkness with no safelight at all, with the exception of a beehive red light well above the sink connected to a waterproof rubberized momentary-contact footswitch on the floor, which I step on for a few seconds at a time to check progress of b&w print tray development. All my color processing is done in light-tight drums. On those infrequent occasions when I feel like experimenting some more with dye transfer film, then I set some small additional red lights with regular on/off switches.

 

[Rudeofus]

Are you writing about ortho film being fogged by red darkroom safelights, or regular film?

 

[DREW WILEY]

It's a risk with all panchromatic films. Ortho Litho is about 2/3 blue sensitive and 1/3 green sensitive, and basically a graphics art material. I keep some 8x10 sheets on hand in the lab for highlight masking. A red safelight would be OK in that case, but I'm so accustomed to working in total darkness that I don't even bother switching the red light on. I don't work with green-sensitive Ortho per se, so can't give a good answer to that.

 

[Rudeofus]

AFAIK panchromatic films have no such sensitivity gap - and they shouldn't - so little surprise, that any common type of safelight will quickly fog them.

When I use my darkroom, I typically use it with a few other folks at the same time, and open trays with toxic/corrosive liquids in complete darkness is a risk none of use want to take. The biggest format we shoot is 4x5", therefore we are well covered with film tanks for all of these. We've also done 8x10" RA-4 and Ilfochrome sheets in rotary tanks.

 

[mklw1954]

I use Kodak Ektacolor chemicals, one-time use of developer and blix in drums and a roller base for continuous agitation, and Fuji Crystal Archive Type II paper (8x10 and 11x14). Using 70ml of developer and blix for 8x10 prints (instead of the typical 60ml recommended) and 140ml for 11x14 prints, and not draining the drum too long, has eliminated streaking and therefore no stop is needed between developer and blix.

If I don't at least cover the developer and blix bottles with the cap after emptying them, and don't cover the "waste bucket" used for spent solutions and bottle rinsates before dilution to pour down the drain, I can feel the chemicals. I think the developer is the culprit. For that reason I would not use trays. There is no problem if I take the simple precautions of using a closed drum, covering the bottles as described, and have some room ventilation.

Results are great.