Dimroom 'safe' lights?

MurrayMinchin · Jan 9, 2023

I'm wondering what people are using for 'safelight' in their alternative process dimrooms.

Just started making salt prints and have been working in a pretty dark room, to eliminate at least one variable which could effect the higher tones in a print. Also, coming from a darkroom environment, it just seems wrong to be turning room lights on while working!

Today I exposed a swatch of sensitized paper to about a Zone VIII density with UV light, then started exposing it to different lighting scenarios.

Have a 7 foot x 3 foot window (always in the shade) covered in 20x24 sheets of rubylith which passed with flying colours...20 minutes, no fog.

Have 7 small LED safelight bulbs (yellow) in bullet lamps scattered around the sink area...20 minutes, no fog.

25W incandescent bulb bouncing off the wall in the coating area...20 minutes, no fog.

25W incandescent bulb in ceiling...20 minutes, no fog.

Thomas Duplex Safelight, vanes open...20 minutes, no fog.

NOMA 60W LED cool bulb in ceiling...fogged paper in 7 minutes.

NOMA 60W LED warm bulb in ceiling...fogged paper in 7 minutes.

Fun project, especially since salt prints are a printing out process so there was no need to mix up any chemicals.

What's your dimroom safelight sauce, and for what alt process(es)?

gone · Jan 9, 2023

I only do straight B&W printing Murray, but it's nice to see someone using actual testing vs a lot of graphs, curves and such. This way you know for sure, it's real world data, and love your system, which found the cutoff points.

My darkroom is already a dimroom, as all I use is a 11W bulb from Freestyle. It's mounted in a standing floor lamp w/ a sheet of Ruby lith over the lamp's plastic frosted part just in case. I like this more than a safelight that's screwed into the wall or ceiling because I can grab it w/ one hand and easily move it to other areas.

ProfessorC1983 · Jan 9, 2023

My results are similar to yours, in that LED bulbs of any light temperature seem to fog at least silver-based processes (salt, VDB, kallitype) quite badly. I just use red safelight since my dimroom is also my darkroom (and in the basement so no need to worry about errant window light).

Vaughn · Jan 9, 2023

Old incandescent yellow bug lamps. Can't find them anymore. But yeah...working in a darker-than-needed dimroom is a hard habit to break.

I now lean big pieces of cardboard over the kitchen windows when processing platiunum prints and carbon prints during the day...and don't sweat the little UV sneaking in. I control the light better when coating, drying, and loading/unloading the contact frames.

MurrayMinchin · Jan 9, 2023

Thanks all for chiming in.

Well, geez...maybe rubylith over the window is total overkill.

Tomorrow I'll try all the safe options on at the same time and see how long it takes for fogging to appear. It's about 20 minutes from getting the dry/sensitized paper ready in the contact frame to it hitting the fixer, so anything past that will be bonus time.

MattKing · Jan 9, 2023

MurrayMinchin said:
Well, geez...maybe rubylith over the window is total overkill.

It just means that if you feel like it, you can also easily make a silver gelatin print too!

MurrayMinchin · Jan 9, 2023

MattKing said:
It just means that if you feel like it, you can also easily make a silver gelatin print too!

Good point...for the foreseeable future going to be sticking with salt prints, then maybe kallitypes, then maybe........

MattKing · Jan 9, 2023

It is fun to be able to make a quick contact print from an old negative.

koraks · Jan 10, 2023

MattKing said:
It just means that if you feel like it, you can also easily make a silver gelatin print too!

In theory.

In practice, the rubylith will pass a little light that will fog sensitive materials like silver gelatin papers. One could give it a try, but I'm not too optimistic about the whole endeavor. Maybe with warmtone papers that are inherently slower.

Vaughn said:
I now lean big pieces of cardboard over the kitchen windows when processing platiunum prints and carbon prints during the day.

Similar setup here; south-facing windows, so something's gotta be done...I've got roller blinds that I pull down when it's grey weather and not much UV about. Or plywood panels made to size of the windows that I can slide in for it to be pretty darn dark. They're a reasonably good fit, so combined with the roller blinds that will catch the odd strip of light seeping through a crack, this makes it dark enough to load and develop film or print RA4.
But I prefer to do 'light-sensitive work' when it's dark anyway.

For 'dim-light' I currently use LED strips; warm white ones for stuff like carbon transfer. If it needs to be dimmer/safer, I can dial 660nm red LED strips to their highest output and have the room bathe in red light that makes pretty much anything easy to see. I can dial them down to make a proper safelight for silver gelatin printing. There are orange 600nm LED strips that I can dim down to the lowest setting, which gives me a quasi-safelight I can use when I've just loaded RA4 paper into the RCP20 and closed the lid; I can then proceed to walk around and load another negative etc.
So it's a combination of light sources, which accommodates for whatever I feel like doing in there.

pentaxuser · Jan 10, 2023

MattKing said:
It just means that if you feel like it, you can also easily make a silver gelatin print too!

Yes I think it was Les McLean that told the story of a photographer, many years ago, with a shop who did his own printing in his basement darkroom but as he was a one man band he needed to be able to see if anyone came into his shop. His basement has a window that was partly below ground level so he covered it with what I imagine was the equivalent of rubylith so that when printing he could still see in any customer had entered his shop without the risk of spoiled prints

pentaxuser

Donald Qualls · Jan 10, 2023

There are amber LED bulbs that fit standard screw base sockets, and are (nearly?) monochromatic at close to the sodium emission line at 589 nm. These are quite bright (a single 7W is really bright in my 8x12 foot darkroom) and should be safe with any materials that haven't had spectral sensitizers added (i.e. alt process coatings, wet plate, homebrew silver gelatin emulsions without erythrosin etc.).

MurrayMinchin · Jan 10, 2023

Donald Qualls said:
There are amber LED bulbs that fit standard screw base sockets, and are (nearly?) monochromatic at close to the sodium emission line at 589 nm. These are quite bright (a single 7W is really bright in my 8x12 foot darkroom) and should be safe with any materials that haven't had spectral sensitizers added (i.e. alt process coatings, wet plate, homebrew silver gelatin emulsions without erythrosin etc.).

I picked up some amber ones at 595nm from superbrightleds.com about 5 years ago. They have a standard bulb base, but the bulb itself is tiny at 1.5 inches in diameter, and are maybe 15W or so bright. Those are the ones above my sink and caused no fog. Also got a couple red ones and they work great as well.

MurrayMinchin · Jan 10, 2023

Pretty sure these are the ones: https://www.superbrightleds.com/s11...uivalent-led-globe-bulb-27-lumens+color-Amber

Donald Qualls · Jan 10, 2023

MurrayMinchin said:
I picked up some amber ones at 595nm from superbrightleds.com about 5 years ago.

Those are probably the same ones I have. Not safe for multigrade printing papers, but I have a red safelight for that.

MurrayMinchin · Jan 10, 2023

Decided to go with all lights blazing, just to see where the limits are. If you can handle the tension, I'll give real time results.

Coated and dried silver nitrate with all LED's on, 25W incandescent bulb pointed towards ceiling in the coating area, red filter vanes down in the Thomas Duplex safelight, and the rubylith covered window.

Began fog test with lights same as above, paper in the sink area, but with vanes fully open and amber filters in the Thomas duplex.

So far up to 15 minutes, no fog.

Getting 20 minutes now, so next update about 10 minutes after the hour.

It just doesn't get any more exciting than this, does it?

MurrayMinchin · Jan 10, 2023

Well, slap my ass & call me Judy...no fog!

25 minutes next.

MurrayMinchin · Jan 10, 2023

After 25 minutes there was a very, very slight increase in the approximately Zone VIII print density of the test swatch.

Exposing for 30 minutes, just to be sure.

MattKing · Jan 10, 2023

Now you need to do the tougher test - a version of the Kodak safelight test, which checks for deleterious effects when one either pre-flashes or post-flashes your print materials.
https://www.kodak.com/content/products-brochures/Film/KODAK-A-Guide-to-Darkroom-Illumination-K-4.pdf
As a Canadian, I guess I need to say "Sorry".

MurrayMinchin · Jan 10, 2023

MattKing said:
Now you need to do the tougher test - a version of the Kodak safelight test, which checks for deleterious effects when one either pre-flashes or post-flashes your print materials.
https://www.kodak.com/content/products-brochures/Film/KODAK-A-Guide-to-Darkroom-Illumination-K-4.pdf
As a Canadian, I guess I need to say "Sorry".

That's a good one, for sure.

Since this will be for UV light source contact prints, I'm expecting to be consistent at exposing for max black time. If there are any heroics needed, it'll probably be done at the digitally enlarged negative stage.

30 minute exposure confirmed a slight density increase.

Have room for one more strip on the swatch, so exposing it for 35 minutes without the 25W incandescent bulb pointing at the ceiling in the coating area turned on, which I think is the culprit.

Pretty much shocked at how bright the room is.

MattKing · Jan 10, 2023

MurrayMinchin said:
30 minute exposure confirmed a slight density increase.

And how much ambient light exposure would increase the density if your UV exposure was enough to give you half of maximum black?
1/4 of maximum black?
1/8 of maximum black?
You need to consider threshold effects.

MurrayMinchin · Jan 10, 2023

Yup, 25W bulb was the tipping point.

So, with a processing/toning time of about 20 minutes until the fixer, everything should be okay.

Seems weird though, to see yellow light streaming out into the hallway from under the door, and to walk in and out whenever I want.

Dim rooms rock.

MurrayMinchin · Jan 10, 2023

MattKing said:
And how much ambient light exposure would increase the density if your UV exposure was enough to give you half of maximum black?
1/4 of maximum black?
1/8 of maximum black?
You need to consider threshold effects.

Not sure if I understand the need to know.

The swatch had an overall UV exposure to a bit higher than a Zone VIII print density, so is very sensitive to fog. Also put a strip of rubylith tape across the swatch so each test had an unexposed area in it, just in case fogging was so severe it created some density in a coated area that saw no UV exposure. All were paper white.

Being a printing out process, the effects of fog become exponentially less as the print tones get darker. It's a self masking process and takes an obscene amount of light reach anything close to black.

nmp · Jan 10, 2023

I am trying to understand this - you are pre-exposing this test strip to Zone VIII and THEN leaving it out in different light conditions? Why not just use unexposed paper?

:Niranjan

MurrayMinchin · Jan 10, 2023

nmp said:
I am trying to understand this - you are pre-exposing this test strip to Zone VIII and THEN leaving it out in different light conditions? Why not just use unexposed paper?

:Niranjan

There was a strip of rubylith tape running horizontally through the swatch when given the Zone VIII print density exposure. The tape was then removed and the swatch was exposed to the ambient light in vertical strips.

Theory is; fogging would occur earlier in the Zone VIII area compared to the rubylith covered (no exposure) area because the paper had already received enough UV light to create density.

None of the taped areas showed any density at all, so using unexposed paper would have given a false result.

MurrayMinchin · Jan 10, 2023

Couple quickie digi-snaps:

Dimroom 'safe' lights?

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