Making Your Safelight Safer

[albada]

Maybe I'm paranoid about safelight safety, but in my round Kodak safelight, I installed a red LED bulb of about 30 watt tungsten-equivalent, and replaced the OC filter with a Rosco #27 "medium red" filter (bought at B&H) that I cut into a circle with scissors. It passed the following safelight-test at 2 meters away for 6.5 minutes.

The test I performed:

Pre-expose a strip of paper to yield a light gray.​

Make a test-strip with it, exposing it to safelight instead of enlarger-light.​

My times went up to 6.5 minutes. Nowhere did the light gray get any darker.

BTW, the LED by itself fails the CD-test, as I could see a little green and blue in some reflections on the CD. But the Rosco #27 removed those colors, so that only red was visible in the CD.
Even through the Rosco 27, that 30 watt-equivalent at 2 meters away is bright. I'll be bouncing the light off the white ceiling, which will be dimmer and even safer.

Mark Overton

 

[AgX]

BTW, the LED by itself fails the CD-test, as I could see a little green and blue in some reflections on the CD.

I doubt everbody knows about a CD-test.

Thus:

In a completely darkened room, reflect the red LED light off the surface of a CD/DVD disc. Look carefully at the reflected light for any faint bands of non-red color, such as blue or green. If you see any, consider filtering the red LED light through a single layer of red Rubylith graphic arts film. If you don't see any, consider giving them a try in a darkroom without filtration.

Always follow up with a proper pre-flashed paper fogging test, just to be sure.

The brightness level of the correct color of red doesn't matter. Problems arise when incorrect colors are present, usually too faint for the eye to see, but not too faint for the paper to see over the course of a few minutes exposure.

Ken

 

[RalphLambrecht]

Maybe I'm paranoid about safelight safety, but in my round Kodak safelight, I installed a red LED bulb of about 30 watt tungsten-equivalent, and replaced the OC filter with a Rosco #27 "medium red" filter (bought at B&H) that I cut into a circle with scissors. It passed the following safelight-test at 2 meters away for 6.5 minutes.

The test I performed:

Pre-expose a strip of paper to yield a light gray.​

Make a test-strip with it, exposing it to safelight instead of enlarger-light.​

My times went up to 6.5 minutes. Nowhere did the light gray get any darker.

BTW, the LED by itself fails the CD-test, as I could see a little green and blue in some reflections on the CD. But the Rosco #27 removed those colors, so that only red was visible in the CD.
Even through the Rosco 27, that 30 watt-equivalent at 2 meters away is bright. I'll be bouncing the light off the white ceiling, which will be dimmer and even safer.

Mark Overton

I share your fear and have added some thin white paper in front of my filters but never considered red LEDs.

 

[john_s]

I've made a few LED safelight arrays. I have settled on some very red ones (660nm) which can be very bright and safe. I made a hand held yellow LED light which I use briefly to inspect a print near the end of development. Yellow is a wonderful relief for the eyes after the red, but alas it's not nearly as safe as the very red ones.

 

[Hilo]

I have the old yellow-green bulbs in my darkroom which is a space of 35 square meters. 12 bulbs in two groups of 6. The bulbs are where the walls meet the ceiling, in "open" wall sockets and always more than 2 meters away from the easels and the chemicals. The walls and the ceiling are painted off-white.

When I expose all these lamps turn off automatically. I do a lot of 50x60cm fiber prints with exposures of 70 seconds and often again that with burning.

This has been my way since the late nineties, in the two darkrooms I had and have. I tested in both darkrooms if any fogging occured, it never did. Apart from total darkness when exposing, I am also used to leaving only one of these lamps on during when the paper comes out of the box and placing it in the easel.

I have only used Agfa Record Rapid and Ilford Warmtone papers.

My only worry is that these yellow-green bulbs dissappear. I think they only make the brighter yellow ones now. For over twenty years I buy the yellow-green ones whenever I see them. I can probably print for another 100 years.

 

[ic-racer]

The OC filters in my Kodak safelights are still safe.

 

[koraks]

I have settled on some very red ones (660nm) which can be very bright and safe.

So have I, but they're not safe by themselves. I need to dim them, and/or add rubylith filtering. Mind you; I've got 5 meters of red LED strips around a small-ish darkroom and at full strength, it's a *lot* of light. Maybe with a lot less of them, they would be safe all by themselves.

I still need to add rubylith filtering to my current strips. In my previous darkroom, I used regular 620nm red led strips with 2 layers of rubylith, and that was sufficiently safe to work with bromide papers provided I didn't leave them lying around for too long.

I like lots of light to work with, if at all possible. Why stumble across in the dark if you don't have to? I'm not going back to the days of 15W incandescent behind an OC filter. I sold off the beehives to someone who fancied them for their interior.

 

[Alan9940]

I've had a Thomas Duplex safelight in my darkroom for 40 years and use it with the "doors" completely closed. I've replaced the filter and paper within the glass inserts, once over all those years and, other than that, never had an issue. My darkroom is comfortably bright and I've never witnessed any fogging issue with any of the papers I've used.

 

[Nicholas Lindan]

A faster safelight test is to tuck a scrap of paper up against the safelight for a few minutes - if nothing develops then it's all copacetic.

 

[koraks]

A faster safelight test

It's also more strict than necessary. A safelight that won't produce any fogging or contrast shifts at a normal working distance may very well give visible fog in the test you described.

A 100% safe safelight of course is nice, but overengineering is not a necessity.

 

[gone]

I've been using a single red bulb that Freestyle sells for cheap for the last 10 years. It's in a floor lamp w/ those bendable arms, so you can bend it to change the light direction. There's also a sheet of typing paper over the bulb to cut down the amount of light.

I just pick it up and move it to where it's needed. The only time it let me down was when I tried some Foma papers and got light fogging on them. That was easily fixed by moving the lamp further back.

 

[AgX]

My only worry is that these yellow-green bulbs dissappear.

Still made in Germany.

 

[MattKing]

I prefer the Kodak safelight test - time consuming and boring, but much more thorough, because it tests the effects of both pre and post exposure.
https://www.kodak.com/content/products-brochures/Film/KODAK-A-Guide-to-Darkroom-Illumination-K-4.pdf

 

[xkaes]

You nailed it, Matt. If you don't run through the Kodak test (above), you are basically wasting your time.

 

[Doremus Scudder]

The Kodak test is the best I know. It's worth doing with every paper you use. Foma papers, for example, don't play well with OC safelights; they need red.

There are lots of safelight solutions from antique Kodak lights to LED bulbs and all kinds of filters, not to mention papers with varying sensitivities. That's why its so important to test whatever combination of safelights you have.

I had a Thomas safelight for a while; hated the thing. It was big, noisy and overkill. My current array of safelights consists of a 10x12" Kodak D safelight which bounces light off the white ceiling, Kodak bullets over the workstations of the dry side with pull chains to turn them on when needed (they stay off most of the time) and a strip of red LEDs covered with rubylith tape above the darkroom sink, above a shelf, so the sink bed itself is in the shade.

I have OC and red 1 and 1A filters for all the Kodak safelights, but usually just leave the 1A filters in; I like the classic red darkroom.

Doremus

 

[albada]

I doubt everbody knows about a CD-test.

Thus:

AgX, thanks for posting that description of the CD test. I should have realized that many folks are not familiar with it.
BTW, I tested my red LED with the OC filter, and it made the green/blue bands stronger. That is, the OC was reducing red more than green/blue. Not what I wanted!

Here's another misconception about testing safelights:
A safelight might be fogging paper even if it stays white after a few minutes of exposure to a safelight. How is that possible?
Paper has a threshold, which means that a certain amount of exposure is required before any tone appears. Thus, when testing a safelight, the paper must be pre/post exposed past its threshold to yield a light gray shade. Only then are you guaranteed to see fogging from a safelight. Fogging will darken that light gray.

Mark Overton

 

[Nicholas Lindan]

Safelights that fog at or below the threshold should be seen as a good thing. They are just flashing your paper for better highlight detail.

I'll take my tongue out of my cheek now.

Safelight safety can become a fetish; I've been in some darkroom's where I have had to look closely to make sure the safelight was indeed on -- "Ah yes, I can see a dim, small square of orange light there across the room. If I feel my way along the wall I should be able to find the enlarger."

I keep my darkroom well illuminated. I like to be able to find where I left the scissors or check that I closed the paper safe door without having to feel my way.

I keep a small Celestron night vision light with me for finding objects that fell to the floor, locating the footswitches, and finding things in the back of cabinets. Available at Amazon et al..

 

[albada]

I prefer the Kodak safelight test - time consuming and boring, but much more thorough, because it tests the effects of both pre and post exposure.
https://www.kodak.com/content/products-brochures/Film/KODAK-A-Guide-to-Darkroom-Illumination-K-4.pdf

I re-ran a safelight test, this time doing it Kodak's way (see Matt's link above).
Result: No fogging even at my final time of 12 boring minutes (2 meters away).

Based on these results, I highly recommend having a red LED bulb shine through a Rosco #27 medium-red gel.

Kodak specifies that you pre-expose one half and post-expose the other half of the strip with the safelight. At first I thought that was not necessary, until I realized that safelight fogging would be in the area of reciprocity failure, and I don't know how the rules of two exposures change there. So I tried both. This is a boring test, but an important one, because we need to know that the safelight isn't fogging our paper.

 

[john_s]

So have I, but they're not safe by themselves. I need to dim them, and/or add rubylith filtering. Mind you; I've got 5 meters of red LED strips around a small-ish darkroom and at full strength, it's a *lot* of light. Maybe with a lot less of them, they would be safe all by themselves.

I still need to add rubylith filtering to my current strips. In my previous darkroom, I used regular 620nm red led strips with 2 layers of rubylith, and that was sufficiently safe to work with bromide papers provided I didn't leave them lying around for too long.

I like lots of light to work with, if at all possible. Why stumble across in the dark if you don't have to? I'm not going back to the days of 15W incandescent behind an OC filter. I sold off the beehives to someone who fancied them for their interior.

I have about 160 separate LEDs, in two banks, with a variable resistor to dim them if necessary (but it hasn't been necessary). The light is reflected from some textured aluminium towards to ceiling and work area, so no direct light. It is bright!

Previous projects required Rubylith, as the spectral was less extreme red.

 

[koraks]

I have about 160 separate LEDs, in two banks

Ok, that's not a huge difference. I have nearly 5m at 60 pcs/mtr, so close to 300. Also reflected against the ceiling, from 3 separate banks across the room. Total power draw undimmed is only around 8W, so not all that much...although for a safelight, it's quite a bit. But...not paper safe at this intensity. Which kind of disappointed me, because I checked the datasheet of the LEDs and they showed no secondary emission peak in the green part of the spectrum. I'm afraid that datasheet is not accurate.

I'm planning to do a writeup on my darkroom lighting setup one of these days; might be interesting for those planning to (re)do their darkroom lights. There's some lessons learned in there, I think.

 

[albada]

[...] I checked the datasheet of the LEDs and they showed no secondary emission peak in the green part of the spectrum. I'm afraid that datasheet is not accurate.

Sigh. I bought some violet (near-UV) LEDs weeks ago for experiments with flashing. The datasheet showed nothing below blue, but the CD-test showed green and even some red. In fact, I got more contrast from royal blue LEDs made by Cree than this no-name near-UV LED, despite Cree's longer wavelength. Based on such experiences, I suggest passing red safelight LEDs through a good red filter.

 

[BMbikerider]

I don't have any angst like you do. Life is too short for hand wringing and over use of the worry beads. I use my DUKA Safelight for both colour and B&W. For colour I turn the light baffles down to 10 and yes I have to be careful, but for B&W the lamp is on fully opened and even after 10 mins there has never been any sign of light fogging at all.
You may disagree but I have been too long at this game not to notice if I have a problem or not.

 

[koraks]

Based on such experiences, I suggest passing red safelight LEDs through a good red filter.

That's what I'm going to do, indeed. In fact, I've already fitted one layer of rubylith over my strip lights, but have yet to do some testing to determine safe levels and how far I can push the light intensity.

Also, I already did that writeup I mentioned earlier. I was doing a software bugfix to the lighting system that turned out to be easier than I thought, so I got around to the writeup sooner than anticipated. Here it is, if anyone is interested: https://tinker.koraks.nl/photography/some-light-to-the-darkroom

This describes the current lighting setup I have for my darkroom, which comprises high-CRI cool + warm white, red for B&W and orange for RA4 color. The latter is not exactly safe in its present intensity, so at some point I'll see if I can reduce it further to actually safe levels. If I can be bothered to...because doing RA4 in the dark is not really a problem. Apart from the safe red level being lower than I like it to be, it all works as intended. And I'm going to fix that red issue as well; I think the rubylith is going to settle this one way or another.

 

[Ian Grant]

Something that's missed is that bright Red safelights can affect the contrast range of variable contrast papers, too bright they don't fog paper, they do just the opposite "Latent Image bleaching" better known as the Herschel effect. This tends to limit the contrast range, it's going to be most noticeable in small darkrooms.

Ian

 

[koraks]

I'm aware of this Ian. Within that envelope, the tendency is to push it as far as I can!