Safelight for RA-4 printing?

[Donald Qualls]

There was a post in my thread on building my own color enlarging head that gave what the poster called "purported" spectral curves for Kodak Endura color printing paper.

Looking at those curves, I was reminded that I've heard conflicting information about color darkrooms: that they need to be totally dark (which would make sense, since the print paper is sensitive to all colors) or that there is in fact a safelight for RA-4 print papers (which, based on the curve given in that post, ought to be at appr. 575 nm, a little redder than the yellow sodium line)

What I note, however, is that the "log sensitivity" at that lowest point, the crossover between magenta-forming and cyan-forming layers, is only about -3 from the peak of the magenta-forming layer's sensitivity, and much less different from the cyan-forming peak.

This seems to me to suggest that either I don't know how to read the units they're using (a very real possibility, if they don't read like dB), or there's only about one stop less sensitivity at this minimum than there is at the paper's maximum, which would imply that the safelight, besides needed a very narrow emission spectrum, would also have to be quite dim.

Dim is okay -- anything is better than total darkness, when your eyes will routinely lose some of their adaptation from the bright image cast by the enlarger, and all that's really needed is some way to confirm the emulsion side of the paper without leaving fingerprints, and to be sure the paper is correctly aligned in the easel and submerged in the chemical trays.

But I distinctly recall being told by a friend who had done RA-4 printing that the darkroom wasn't all that dark.

Which is it?

 

[cmacd123]

Well, the data sheet for the paper says:

<quote>
DARKROOM RECOMMENDATIONS
Handle unprocessed paper in total darkness. Be sure that
your darkroom is lighttight. Eliminate stray light from
timers, LEDs, etc.
Note: Using a safelight will affect your results. If absolutely
necessary, you can use a safelight equipped with a KODAK
13 Safelight Filter (amber) with a 7 1/2-watt bulb. Keep the
safelight at least 1.2 metres (4 feet) from the paper. Keep
safelight exposure as short as possible. Run tests to
determine that safelight use gives acceptable results for
your application.
</quote>

imaging.kodakalaris.com/paper-endura-techpub-e4070

 

[NortheastPhotographic]

I'm about to purchase the Heiland LED safelight with the color paper mod. Supposedly this as a B&W mode, a color paper mode, and a white light mode. It's quite expensive for a safelight but I'm going to be using Ilford Direct Positive, color papers, and of course normal B&W papers and I want to be sure that my safelights are indeed safe, so to me the luxury is worth it. I once i have it set up I can report back about the brightness level.

 

[pentaxuser]

I have no knowledge of what is available in the U.S. but here in Europe there are colour safelights called DUKA which work fine with RA4 paper. They use a sodium light that does indeed emit a very narrow spectrum of light in that band to which the paper is relatively insensitive. The intensity of the light is controlled by mechanical shield which will give from almost no illumination to extremely bright and you can obviously perform safelight tests at increasing illumination until you get to the point where the intensity and duration of exposure starts to affect your paper

In my experience the safe intensity of light is certainly enough to see what you are doing quite comfortably. If these lights didn't exist I would not bother with RA4 at all. I have tried a similar light to the Kodak 13 and after about 15 mins still couldn't see my hand in front of my face so I found it useless. The DUKA operates on a different principle as mentioned above

I believe there are similar sodium lamps in the U.S. So yes in my experience they do work and I cannot imagine how I would do RA4 in total darkness. Well worth getting one IMO

pentaxuser

 

[Wayne]

I cannot imagine how I would do RA4 in total darkness.

With your hands by feel, of course. I only use the safelight to bring the paper from enlarger to tray, then i usually shut it off just out of paranoia. I've left it on too with no noticeable effect but I'm still superstitious.

As for what I use, its whatever safelight filter PE used and recommended. Can't remember because I haven't printed color in over a year, unfortunately.

 

[DREW WILEY]

I recommend total darkness and am accustomed to it. For something tricky like loading a heavy roll of RA4 paper onto the cutter reel, I have a little Jobo Minilux light with a neckstrap that has tested safe for brief use. The recommended filters for Kodak's old beehive and rectangular lights are so dim at recommended distance that they're almost useless. I haven't tried the Duka or Jobo Maxilux. Fuji RA4 papers specify total darkness, but test regardless of brand.

 

[pentaxuser]

I admire those who can spend hours in a darkroom in total darkness for nearly all of the time and produce excellent RA4 prints without it being a really exhausting chore. However I would contend that most darkroom users cannot successfully do that without it being a relaxing comfortable experience. As we are talking about what should be an enjoyable experience then anything that can return us to that enjoyable experience is to be welcomed

The DUKA or similar sodium safelight fits that bill for me and is certainly worth trying for those who otherwise would find RA4 printing a real chore or at worst would abandon it

pentaxuser

 

[Wayne]

I recommend total darkness and am accustomed to it. For something tricky like loading a heavy roll of RA4 paper onto the cutter reel, I have a little Jobo Minilux light with a neckstrap that has tested safe for brief use. The recommended filters for Kodak's old beehive and rectangular lights are so dim at recommended distance that they're almost useless. .

Indeed, I use a beehive and all its good for is not breaking your neck in total darkness, and making sure it gets in the right tray. But that's gotta be worth sumthin. i dont use a light around the enlarger, I do all of that by feel.

 

[DREW WILEY]

Yeah, the Kodak filter can tell you which end of the sink room is which, but that's about all.

 

[Donald Qualls]

Ugh. I guess it's time to look at emission spectra for yellow LEDs and filtration curves for various gels. I can probably come up with something that will let me see well enough to find a sheet of paper on the counter.

Doing everything by feel is less than desirable; my day job has some negative effects on my finger sensitivity (they recover if I get a week or two off work, but that only happens once or twice a year).

 

[mshchem]

I use Thomas safelights with the color filter. Never had a problem with fogging. Yes they are low pressure sodium, they emit 2 lines, I would have to look but very typical Na emission lines.
You can see, BUT, you need to be in the dark long enough to get your eyes "adjusted" to the dark. It takes up to 45 minutes or longer for human dark vision to fully kick in. If you turn on the room lights, you start over.
I have had good luck with these lights, if you wait at least 15 minutes, it's amazing how much you can see.
The Kodak #13 filters are so dense you can't even tell if their on at first.
Only real way to see in the dark is with IR goggles and IR illumination. Usually too bright. Pain in the butt.

I never bothered with safelights when I was really printing color. Like Drew mentions a little dim amber LED like the Jobo, is great for finding your way around, but as Jobo will tell you keep it away from the paper.

No free lunch.

 

[koraks]

I experimented a bit with a tiny Durst safelight, the one that has 3 filters that can be rotated, one of them being specifically for color paper. I found it way too dim to be of use and when I positioned it in such a way that actually allowed me to see anything, it fogged the paper.

I find the only thing I really need is some "navigation beacons" in my darkroom so I can tell where my enlarger is, where the box of paper is and where the processing trays are. For that purpose I cut some of those glow in the dark stars fo children's bedrooms into pieces and glued them in a few different (strategically chosen) places in my darkroom, in such a way that I can see them but the glow doesn't cast onto the paper. Works a treat!

 

[halfaman]

I don't consider myself an skilfull person, more on the clumsy side, but I can work without problems in total darkness doing RA-4. It is a lot easier than it seems.

And of course, I turn on the light when I finish a copy.

 

[Ian Grant]

I have Kodak beehive safe=lights with Wratten 10 & 10H filters (Ilford 908), I use one to illuminate my timer, I have it pointing away from the enlarger area an Nova slot processor, so no direct light from falls on the paper.

Yeah, the Kodak filter can tell you which end of the sink room is which, but that's about all.

What Drew says is initially true, however after a while you can make out much more and it's easy to work.

Ian

 

[Bikerider]

Like Pentaxuser I would not/could not use RA4 in a completely blacked out darkroom, there are too many things to do when printing colour that make it impractical, especially if you use a drum as opposed to a Nova deep tank.

If the light is kept low as low as you can manage (There is a graduated scale) then after a while it is not bad at all. I use Kodak Endura paper which is only available as a roll so need a level of light where I can put the paper through a guillotine. I have done a sensitivity test with my setup and only after 25 seconds of reflected light off the ceiling is there ANY trace of fogging and is so faint and can only be detected by comparing with a pure white surface, so for all intents and purposes can be ignored.

Replacement bulbs are as far as I know unobtainable having been discontinued several years ago, fortunately I have two spares.

I have found that, contrary to what Ilford state, you can use one of the Duka lights without the B&W red filter in place and I don't get noticeable fogging, even when the lamp is at full brightness and exposed for around 3 mins.

 

[koraks]

I have done a sensitivity test with my setup and only after 25 seconds of reflected light off the ceiling is there ANY trace of fogging and is so faint and can only be detected by comparing with a pure white surface, so for all intents and purposes can be ignored.

Even before fogging is visible, subtle shifts in color balance can be expected. This means your 'safe time' is probably significantly shorter than 25 seconds if you aim for consistent reproduction.

 

[pentaxuser]

Donald, for the future it sounds as if an IR light is the way to go? I have never used one and I have the DUKA but given the difficulty of obtaining new lamps and the price if you can find one, it might be as cheap to buy an IR light. I take it that such a light is fine for RA4 paper and if I have understood the science correctly there is no max limit to how long it can be on i.e. it is always safe. The IR light looked to be pretty bright in a video I saw in which owner loaded a film without any adverse effect on it

pentaxuser

 

[Bikerider]

Even before fogging is visible, subtle shifts in color balance can be expected. This means your 'safe time' is probably significantly shorter than 25 seconds if you aim for consistent reproduction.

In all of nearly 30 years use with a Duka I have never had a problem that wasn't of my own making. When it went wrong it was because I did or didn't do something I should have.

 

[Wayne]

Like Pentaxuser I would not/could not use RA4 in a completely blacked out darkroom, there are too many things to do when printing colour that make it impractical, especially if you use a drum as opposed to a Nova deep tank.

If the light is kept low as low as you can manage (There is a graduated scale) then after a while it is not bad at all. I use Kodak Endura paper which is only available as a roll so need a level of light where I can put the paper through a guillotine. I have done a sensitivity test with my setup and only after 25 seconds of reflected light off the ceiling is there ANY trace of fogging and is so faint and can only be detected by comparing with a pure white surface, so for all intents and purposes can be ignored.

Replacement bulbs are as far as I know unobtainable having been discontinued several years ago, fortunately I have two spares.

I have found that, contrary to what Ilford state, you can use one of the Duka lights without the B&W red filter in place and I don't get noticeable fogging, even when the lamp is at full brightness and exposed for around 3 mins.

Why would you do drums in the dark, other than loading them? Scratching my head...

 

[Wayne]

I don't consider myself an skilfull person, more on the clumsy side, but I can work without problems in total darkness doing RA-4. It is a lot easier than it seems.

And of course, I turn on the light when I finish a copy.

Right, I realize it may not be for everyone, especially someone with mobility impairment, but for healthy humans its just not that difficult. If you can load drums or film holders in the dark you can print RA-4 in the dark, I would think. Remember that archaic word, what did they call it again...? Oh yeah, darkroom.

 

[Bikerider]

I did another test with my Duka again after I had -repositioned it to reflect off the white ceiling. I made 4 test exposures using a test strip printer, he 1st exposure was 20 seconds and the other 3 were 20 seconds each making a total of 80 seconds. There was a 5th strip right at the start which was not exposed and to be honest I cannot see any difference between the control strip and the strips that has been exposed

 

[DREW WILEY]

I've been loading drums in total darkness for decades, clear up to big 30x40 inch ones. The great advantage of a drum is that I can do the actual processing outdoor afterwards and avoid nearly all the color chem vapors.

 

[NortheastPhotographic]

I ordered the Heiland, should arrive later this week. I'll report back on it's use and installation.

 

[pentaxuser]

I did another test with my Duka again after I had -repositioned it to reflect off the white ceiling. I made 4 test exposures using a test strip printer, he 1st exposure was 20 seconds and the other 3 were 20 seconds each making a total of 80 seconds. There was a 5th strip right at the start which was not exposed and to be honest I cannot see any difference between the control strip and the strips that has been exposed

What setting on your DUKA 50 is this? I think the 50 has a slider that goes from 0-50. I have the DUKA 10 and my slider goes from 0-35 but it is a reasonable assumption that my 0-35 covers the same shut to fully open as does your 0-50 so I can work out what your setting means on my 0-35. 80 seconds seems like a pretty good margin to me.

Thanks

pentaxuser

 

[Chan Tran]

There was a post in my thread on building my own color enlarging head that gave what the poster called "purported" spectral curves for Kodak Endura color printing paper.

Looking at those curves, I was reminded that I've heard conflicting information about color darkrooms: that they need to be totally dark (which would make sense, since the print paper is sensitive to all colors) or that there is in fact a safelight for RA-4 print papers (which, based on the curve given in that post, ought to be at appr. 575 nm, a little redder than the yellow sodium line)

What I note, however, is that the "log sensitivity" at that lowest point, the crossover between magenta-forming and cyan-forming layers, is only about -3 from the peak of the magenta-forming layer's sensitivity, and much less different from the cyan-forming peak.

This seems to me to suggest that either I don't know how to read the units they're using (a very real possibility, if they don't read like dB), or there's only about one stop less sensitivity at this minimum than there is at the paper's maximum, which would imply that the safelight, besides needed a very narrow emission spectrum, would also have to be quite dim.

Dim is okay -- anything is better than total darkness, when your eyes will routinely lose some of their adaptation from the bright image cast by the enlarger, and all that's really needed is some way to confirm the emulsion side of the paper without leaving fingerprints, and to be sure the paper is correctly aligned in the easel and submerged in the chemical trays.

But I distinctly recall being told by a friend who had done RA-4 printing that the darkroom wasn't all that dark.

Which is it?

It's the log so -3 is 1/1000 less sensitive than that peak or about 10 stops.