Safelight question (red safelight with MG materials)
So - I'm JUST ABOUT ready to make my first print in my fancy new exposing room. I thought I was being clever when I ordered a red ortho sleeve for my fluorescent safelight. However - it occurred to me that, when using multigrade materials - that this might throw things off a bit - if not fog the paper outright with it's (possibly) minor magenta component... anybody have any ideas about this??
Might not be the best move, but test it
Yes, multigrade is sensitive to some degree of the red wavelengths.
Test the situation. In the DARK, flash some paper under the enlarger, til you can fiigure how much light it takes to get a barely disernable grey with no multgrade filter in the enlarger ( contrast will be about 2.5 with no filter on most brands). Put a sheet under the enlarger set to say project a 11x14 image size at f16, and set the timer to something like 4 seconds. Cover all but 1" of say an 8x10" paper with a mask - like a piece of cardboard. Expose, then uncover another inch, without moving the photo paper, expose again, etc. When the sheet is entirely uncovered, then move (again in the dark) to the developer tray, and toss it in for a couple of minutes before turning your 'safelight' on. It may take a few tries to find out how long it takes to flash to the first shade of grey. Evaluate when dry under a white light source, not the safelight while the print is in the developer.
Then flash a whole piece of photo paper at once for the just before flashed to lightest grey exposure time. Put a series of coins on the paper, after it ahs been exposed and turn on your 'safelight'. Take the coins off at 30 second intervals until you make it to 5 minutes. It helps in this test to circle the coins and write the times on the face of the photo sheet with a sharpie marker. Process the paper, again in the dark for a few minutes, then pop it into the fixer for a minute before turning on the lights. You now should know how long you have before your 'safelight' starts to affect your particular paper that you use.
If it is a resin coated B&W paper (the easiest by far to start with, and you might never move to fibre), then you likely can get it fully developed in a bit more than 2 minutes unless the developer is freezing cold, pop it in the stop for a half a minute and have it in a rapid fixer for a minute and no longer substantially light sensitive.
If you do run into trouble earlier than that, then get out some black paper, cardboard and mask, turn out some tubes, etc. to cut the amount of light this 'safelight' system puts out until you can lay you hands on an OC safelight filter and safelight.
But print for heavens sake. I still can remember the thrill of printing in my darked out bedroom with an old enlarger borrowed from high school over christmas vacation one winter over 24 years ago now. I had the enlarger of a fold up card table, and processed in trays laying on top of a piece of plywood and a big piece of plastic on top of my bed. A kodak bullet safelight sitting on the same card table was bounced of the back wall and roof of the room. And man did I print, and have fun.
Within the year I had my own corner of the basement darkroom with a home made plywood sink that I still use. By the last two years of uni I was in an old house that had a second floor kitchen from before six of us rented the house whole. From there i put out the engineering society yearbook photos.
There have been three other darkrooms since then, til my present one. Even if no one else likes what you do, keep at it, because it can be a whole lot of fun, and if you keep notes, you will get better with time. My first prints from that first darkroom look like not so great today ( washing in the toilet tank was probably part of the problem), but they still feel great to me.
I use a red safelight with MG materials and have no problems whatsoever. You said flourescent sleeve? I assume it's for a 40 watt tube? Pretty bright - be sure to keep it far enough away to prevent fogging. Do a simple safelight test to be sure. Same as making a test strip, without the enlarger. Exposure increments of 30 seconds to 1 minute. The first hint of gray over paper white is the exposure limit to safelight. I can go several minutes with mine. Plenty long enough to completely process a print with no hint of a problem.
MG papers are sensitive to Blue and Green light, not Red.
I have posted the sensitivity curve of Ilford MGIV paper here on APUG somewhere.
We use Paterson red safelights in our darkroom. Once we tested them at one foot (30cm) from a variety of papers including several VC for half an hour, using a similar 'coin test' to that already described. No problem. Red is safer than orange. (Bear in mind what we do for a living -- see www.rogerandfrances.com -- and you'll see why we do such tests...)
Originally Posted by Sparky
Incidentally, VC isn't sensitive to magenta: it's sensitive to blue and green, hence the use of yellow (minus blue) and magenta (minus green) to block the wavelengths to which it is sensitive.
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Thanks for all the advice - I was under the impression that MG papers (yes Mike - it's fibre only) were very similar to color papers in having separate layers for distinct light sensitive materials, each sensitive to a different spectral group (except here - it's not dye coupled - just a higher contrast emulsion). Since magenta filters were added to increase contrast - I figured there MIGHT be some spectral overlap in my safelight - into the blue region that the magenta filters traditionally cover - I wasn't so much expecting fogging so much as something like a grade 5 pre-flash... which is to say - perhaps I might see a bit of a contrast kick from it. But I suppose there really are no substitutes for testing...!
Anyway - the reason I did this (went with the red safelight) is because prints I've done in the past (on galerie) when I was doing tube-only processing seemed to have significantly more 'snap' (not exactly contrast - perhaps just better whites?) than almost all other prints. And so - I wanted to get a similar result, in case this was a factor. We'll see, I suppose.
As for the risk of overexposure with the safelight. It's buried deep insidea lighting cove reflected by deep yellow (amber) walls - which should help remove any blue. There's no direct light from the safelight visible ANYWHERE within the darkroom, except INSIDE the cove. So that would only matter if you were something the size of a rodent.
Red safelights are red only and emit no blue light.
Magenta filtration passes red and blue (think of it as minus green), and when using magenta for VC papers, it's the blue component of the magenta light that affects the high contrast layer of the paper.
Red safelights are safer than yellow for most VC papers, as they emit less light near the green portion of the spectrum. Look up the curve PE mentions.
A "real" red ortho sleeve filter shouldn't pass any blue light. Find a transmission curve for a Wratten 29 filter and you'll see about what a rubylith or ortho filter should pass. By definition an ortho filter shouldn't pass blue light.
For what it's worth, I tried one of these fluorescent sleeve safelights and experienced fog. Nothing I tried made this sleeve "safe". I now use red LEDs for MG and they work well.
Red is safe for variable contrast papers - maybe more safe than the standard "OC" spec filters recommended for the application. "OC" filters give you a little more visibility in the darkroom and that's why they are popular and recommended. It's a good compromise. Used as directed, an OC safelight should cause no problems. But I'm always a bit leery of filtered floursecent lights in the darkroom. Sensitized papers are very likely to have some sensitivity to UV light and some flourescent lamps emit a fair amount of UV radiation. The higher color temperature lamps (read daylight balanced) are more likely to do this than the warm white variety. All flourescent lamps will glow for a while after they've been switched off. The problem of course is that the filter material on your flourescent tubes may not be completely effective in blocking all blue and ultraviolet light. Adding to the complications is the fact that compared to standard tungsten bulbs of similar wattage, flourescents pour out quite a bit more light. You'll have to test to make sure your light is safe, but don't be overly surprised if your setup fails the test.
Most red lights are not pure red. Even if they removed say 99.999% of the shorter wavelenghts you'll still have 0.0001% left. Give that enough time (or power) and you will fog the paper. I'd guess most practical filters leak actually a lot more light. The same applies for any non-monocromatic light source such as leds. My red led safe lights are *very* bright. Fortunately the light is mostly red. However, if the spectrum is split with eg. a prism yellow to green range is definately there and even a tiny bit of blue I think.
In practice my safe light get me over 25min with MGIV RC (did not test longer) whereas it fogged Kentmere in a few minutes. Kentmere seems to be more sensitive to yellow or yellow-green range I guess. A red filter solved that (by removing more the other bands). Some filters can be very tight, even though most are not. My led-based safelight can be brigher that my red filtered enlarger if measured by fogging capability.
Datasheets can mislead you with leds. They might specity 20-30nm bandwidth (usually the point where 50% of the peak power is available). A look at the graph with a scale 100-0% seem to drop exponentially towards zero very quickly. However, the tiny bit is usually still there. Drop from say 100->0,5% is just 8 steps, yet it looks like zero on a graph. Is that 8 stops enough? Might be, might not, depending on the power level.
Certain light sources like sodium vapor lamps consist inheritantly mostly amber light (at very narrow spikes) and are a lot safer. Monocromatic sources like lasers are another safer thing too.
Anyway, I've not fogged paper with very bright red light if it is pure red. Very bright 100% here means enough to read at 10-20% power level. It was ok to raise the red too, if the source was filtered more tightly. It is not about paper being red-sensitive but the small fraction that is not red.