Red Bulb for Nuarc Safelight?

[HT Finley]

Having been in the printing business all my life, I've become enamoured with the Nuarc Safelights as pictured. But they were made for litho film, which was highly tolerant of most any kind of red light. No matter how bright, the film was comletely blind to it. Litho film was extreme high contrast. Dense as sheet metal. It was either black or pinholes. There was no middle ground. In the later years before computers took over, it was increasingly difficult to find litho film. They had switched to rapid access film, which was less dense. The Nuarc lights seemed to work as long as you didn't blast the room out with them. That was just a recollection. Anyway, I still believe the Nucarcs are good lights adaptable to photography if you put the right bulb in them. No more 15 and 25 watt incandescents like originally. But certainly there are red LED bulbs nowadays you can put in them and have a GREAT safelight for any kind of paper. I don't want to hear any talk about how red lighting is hard to see by compared to amber. Red lights worked excellent in submarines and darkrooms for years. But I understand that there are red LED's that are terrible for print paper and some are good. I have Lowes and Home Depot in the vicinity. What LED bulb would work well standalone, and even better in the Nuarc fixture? Thank you.

[koraks]

Honestly I'd go online and order an arrangement of fitting RED led bulbs and use the ones that test well with your setup. Why bother with white ones if you're going to filter out anything but red, with only the balancing act remaining of the filter transmission vs the unwanted spectrum emitter by the bulb? If you take a red bulb to begin with, secondary emissions in the green and yellow part will be small to begin with and attenuated even further by the filter. I guess the polar bears will hug you, too, because you're not wasting any energy by making light you then dissipate inside a filter.

I hear you on the red visibility bit, btw. I like my safelight red, mostly because it's the most universal color that suits the widest range of papers. Film (litho, x-ray etc) will be fussier simply because of high sensitivity. https://tinker.koraks.nl/photography/some-light-to-the-darkroom/

[Tin Can]

Our oldest member, his name eludes me right now

Suggests using a CD/DVD as prism as it will show the spectrum of light from a dim bulb (pun)

It works very well for spectrum detection visually

This is the new 2 watt RED LED that was 1 watt and better, as it was weaker

The listing used to include all data

This new 2 watt needs distance and bounce

https://www.superbrightleds.com/s11-led-bulb-7-5-watt-equivalent-led-globe-bulb-27-lumens

[John Layton]

Ha...I'd always associated Nuarc with plate burners and never something so tepid as a safelight...

[koraks]

[QUOTE=Tin

The listing used to include all data

[/QUOTE]
Except for the data you'd actually need for this application. Such as an emission spectrum plot.

[HT Finley]

Honestly I'd go online and order an arrangement of fitting RED led bulbs and use the ones that test well with your setup. Why bother with white ones if you're going to filter out anything but red, with only the balancing act remaining of the filter transmission vs the unwanted spectrum emitter by the bulb? If you take a red bulb to begin with, secondary emissions in the green and yellow part will be small to begin with and attenuated even further by the filter. I guess the polar bears will hug you, too, because you're not wasting any energy by making light you then dissipate inside a filter.

I hear you on the red visibility bit, btw. I like my safelight red, mostly because it's the most universal color that suits the widest range of papers. Film (litho, x-ray etc) will be fussier simply because of high sensitivity. https://tinker.koraks.nl/photography/some-light-to-the-darkroom/
Thank you for this link. If I understand it right, most common red LED's are 620nm and can fog paper. But apparently if the red is 660nm wavelength, then this is about as pure red (and safe) as a red safelight can get. So sticking those in the Nuarc would filter most any remainder of the "bad light" and make for a terrific safelight for any B&W paper. No more worrying that one brand of paper likes OC or OA or 1A and another likes brown, or light amber or dark amber, ar any other Baskin Robbins flavors. As I understand it, ALL papers can deal with the correct common red. Correct me if I'm wrong. I wonder how Fuji HRT green would tolerate it.

[koraks]

As I understand it, ALL papers can deal with the correct common red.
This is how I understand it as well, and apart from panchromatic materials of yesteryear (Panalure for instance), AFAIK all current B&W papers tolerate a red safelight.

However!
The LED situation is more complicated than just the 620nm vs 660nm wavelength. The devil is in the detail. Even a 660nm LED can emit secondary wavelengths. If you look at the wavelength plot of a 660nm LED, it's generally a typical bell-curve/normal distribution. The slopes of this bell curve, especially the left one, can extend into the range that's 'visible' for B&W paper, particularly the low-contrast emulsion(s). This is particularly relevant if you work with high light intensities, as I like to do. The more red light you throw at the room, the more these tiny fractions of yellow and green light add up and create problems.

Then of course there's the Herschel (?) effect that causes high intensities of 'safe' red light to still affect contrast (reducing it) of B&W materials.

Particularly the first issue is probably why @Tin Can ran into trouble with his 2W LED bulb and not its 1W predecessor. It also explains why I made that somewhat snarky comment about crucial product information missing from the sales web page! (This information is usually missing, BTW).

The latter issue is more of a concern these days now that we have cheap and easy access to nearly monochromatic light at high intensities. Back in the old days, you'd have to use big bulbs with filters that would visibly degrade due to the heat of the bulb as pretty much the only way to create bright red light, so logically we settled for a couple of beehives with tiny fridge bulbs behind them. No problems with Herschel there. Throw a handful of power LEDs or strips at the problem and all of a sudden we have to think about these things.


Correct me if I'm wrong. I wonder how Fuji HRT green would tolerate it.
It may do fine with your setup, but it will surely fog under by present safelights unless I dim them all the way down. Perhaps I get away with it in that case. xray film is far more finicky about safelighting conditions than printing paper, I find. In my previous darkroom, I had a little red LED bulb similar to Tin Can's hanging over the development tray area with two layers of rubylith over it. This was safe enough to do develop by inspection on xray film. Quite convenient, and bright enough to work by, although still dim by my standards.

[HT Finley]

Well I'm going crazy searching the internet for a decent red LED that can be put inside this Nuarc. The reason I'm so insistent in wanting to use it is because it will be a last firewall against any spurious colors from a bulb. As for buying rubylith and amberlith, it was once common as dirt. I suppose there's a printshop out there still doing paste-up artboards and Kenro cameras and NuArc plate burners, but I doubt they are making much of a living out of it. Heck, I folded up shop in 2016, and I WAS using computer and laser plates and running them on a Hamada 700 press. Now, printshops don't even have a printing press at all. Come to think of it, what print shops? There aren't any anymore hardly. But I got 3 of these NuArc safelights just like the photo I posted, in excellent condition. And I KNOW they can be adapted to print paper.

[koraks]

I was fortunate enough to find a pack of rubylith sheets (roughly imperial size, give or take) in my local arts supplies store. No clue why they stocked it. I bought enough sheets to last me years and years. Maybe I'll go back for more one of these days. Like you said, it used to be common as muck, nowadays it's scarce material.
Don't the screen printing boys and girls use it as well?

[HT Finley]

I suppose there's printers and screen printers and any other kind out there still using rubylith. Maybe. When you say you have enough to last years, that's true if you want it to just be red and nothing else. But if you try to use it for it's intended purpose, after a few very short years it won't peel up from the clear base. Unless you have the patience to peel it up in tiny little slivers and pieces at the time. In other words, its bad. I'd hate to think what the stuff must cost new now. NOS rubylith is useless

[koraks]

I didn't all that much for the stuff I got. I suppose a few Euros per sheet, certainly not more, or I would have limited my intake.

Can't tell about the performance of old rubylith; I still have some of the first rubylith I bought but that's only something like 6-7 years ago and I haven't tried it lately. Last time I used it, it peeled fine. Storage conditions probably matter a lot.

Btw, I use some for darkroom light filtering, but most of it actually goes into making masks for contact printing alt. process materials such as carbon transfer. So I get to do the peeling as well; so far without any problems provided the tip of the blade on my X-acto isn't blunt.

[Ron McElroy]

I use one of those safelights in my dark room. It has 2, 7 watt white bulbs in it and they have lasted for many years. No fogging on paper. It is on a wall away from the sink... I also have some of the old 1 watt LEDs that Tin Can posted. Again they work great as well. The one watt amber ones are not safe. I am a retired expat from the printing/graphics world as well.

[maltfalc]

Well I'm going crazy searching the internet for a decent red LED that can be put inside this Nuarc. The reason I'm so insistent in wanting to use it is because it will be a last firewall against any spurious colors from a bulb. if you want to eliminate unwanted frequencies of light as much as humanly possible, get a laser diode rather than an led.

230633

[Tin Can]

Did include chart plot, before...


Except for the data you'd actually need for this application. Such as an emission spectrum plot.

[j.e.simmons]

As for how Fuji X-Ray film handles red LEDs - I tried red LEDs from Lowes, Home Depot, and superbrightled. All were reputed to work, but I found that all fogged with 10-minute exposures with the light about three feet away. I put the Lowes LED in a Kodak bullet safelight with the recommended GBX-2 and have no fogging. I assume this filter would be OK for paper, but haven’t experimented yet.