Flourscent light: how long before safe in the dark?.

Bruce Osgood · Oct 5, 2010

I'm nearing the end of my darkroom rebuild. The ceiling has a large, bright flourscent 4 bulb lamp for illumination when not 'in the dark'.

I believe there is a period of time when a flourscent lamp is turned off and it is 'safe' to expose paper or film in the dark.

Can anyone elaborate on this?

Thanks,

Robert Hall · Oct 5, 2010

1 hour. I personally guarantee it.

Kidding aside, I have seen mine glow for a little over 30 seconds when I am quite used to the dark. I think some of it depends on how much charge is left in the tubes after the power is cut.

Paper is quite slow, so I think you should be fairly safe after a minute or so.

I have incandescent lamps for most of my lighting and try not to use the florescents unless I am doing a light safe process.

rmolson · Oct 5, 2010

after glow

After glow

I fought fogged film for year thinking I had light leaks in my cameras. Eventually l discovered it was the UV from the lamps being absorbed into the photo paper for focusing on my easel, not the lamps them selves Being a neat freak I set out every thing on the (clean) white paper before going dark to load the reels . Once I changed that habit and also covered my Time O Lite dial ( which was bright enough to almost read a paper bysafe for darkroom use my a--) my fog problems ceased.

Dan Henderson · Oct 5, 2010

In addition to the fogging issue, remember the color shift that fluorescent lights produce. My darkroom is lit with incandescent bulbs, the basement room just outside the darkroom with fluorescents. The pinky color that I aspire to on my lith prints take on a garish green cast when I move them from one light source to the other.

Jim Noel · Oct 5, 2010

I believe 15 minutes is likely sufficient, but 30 would be safer.
I removed all fluorescents from my darkroom and replaced them with incandescent fixtures.

Bruce Osgood · Oct 5, 2010

Wow, even 15 minutes seems long. I might better reconsider the overhead lighting.

Thanks all.

Bob-D659 · Oct 5, 2010

Depends on the tubes, the ones in our kitchen glow for at least a minute, the two in the darkroom are black in three seconds. The green glow in the dark sticker on the speed easel glows for at least an hour.

fschifano · Oct 5, 2010

Bruce Osgood said:
Wow, even 15 minutes seems long. I might better reconsider the overhead lighting...

That's probably the smart move. You're going to get answers all over the place from "It's safe as soon as you turn them off," to "Wait at least an hour before opening any light sensitive materials." The truth is that florescent tubes do emit an afterglow, the amount and duration of which is highly variable. Any exposure of light sensitive materials will have an effect, be it noticeable or not. But remember that exposure is cumulative. While a single exposure may be insignificant, add them up and you can wind up with some fog. When I set up my darkroom, I'd considered using an overhead florescent fixture containing two, four foot long, 48 watt tubes. After seeing them continue to glow after having been turned off, I quickly reconsidered. A singe 60 watt incandescent lamp is more than enough for the space I have and I went with that instead. As far as I'm concerned, florescent tubes have no place in the darkroom unless they're covered with safelight filters, and even them I'm leery of them.

BetterSense · Oct 5, 2010

Even though my small darkroom gets hot inside, I still use incandescents. Partly because the afterglow fears, but mostly because the light from them is just rubbish compared to good old black body radiation.

Q.G. · Oct 5, 2010

If not wired correctly, fluorescent tubes continue to pulse and emit low level light when switched 'off'.
Only when the power supply is cut completely can you be sure they are really off.

David Brown · Oct 5, 2010

Bruce Osgood said:
Wow, even 15 minutes seems long. I might better reconsider the overhead lighting.

Thanks all.

Bruce: I did this in my new darkroom. I took down the tubes and put up standard fixtures.

RalphLambrecht · Oct 5, 2010

It's my opinion that fluorescent lights don't belong into darkrooms. After-glow is one issue, but I think that's a bit over-rated. Still, if I turn a light off, I like it to be off!

That said, the bigger 'danger' with fluorescent lighting to me is how bright most of them are. A high level of illumination is not what you want for print evaluation. A print, looking good under bright lights will look to dark and dull in dimmer lights. It's far better to get the print just right under dimmer conditions, because if lighting levels increase, so does the apparent image quality.

MattKing · Oct 5, 2010

Flourescent lights give bright, shadowless illumination without adding much heat - excellent for cleaning up .

I'd leave them in, but add special purpose lighting for print evaluation and other tasks that might be affected by after-glow.

RalphLambrecht · Oct 5, 2010

MattKing said:
Flourescent lights give bright, shadowless illumination without adding much heat - excellent for cleaning up .

I'd leave them in, but add special purpose lighting for print evaluation and other tasks that might be affected by after-glow.

Sound advice!

2F/2F · Oct 5, 2010

I agree that fluorescent lights are not the best choice for the darkroom. However, as a workaround on a dedicated fluorescent fixture that is already installed, you can make a hinged cover that block the light and secures with Velcro. If the ceiling is high, you can use a rod with a hook, and an eyelet on the cover so you can take it back off without a ladder.

nickandre · Oct 5, 2010

For paper don't worry about it. For film, use a changing bag or a dark room with incandescent bulbs.

Black and white paper is not nearly sensitive enough. Color paper is not sensitive enough, AFAI can tell.

nickrapak · Oct 5, 2010

MattKing said:
Flourescent lights give bright, shadowless illumination without adding much heat - excellent for cleaning up .

I'd leave them in, but add special purpose lighting for print evaluation and other tasks that might be affected by after-glow.

Now that's a bright idea!

Lee L · Oct 5, 2010

MattKing said:
I'd leave them in, but add special purpose lighting for print evaluation and other tasks that might be affected by after-glow.

That's what I've done for the last 30 years. I use either GE Chroma 50 or Phillips Colortone C50 fluorescent lamps, both of which are 5000K with CRIs (color rendition indices) of 90 and 92 respectively. These lamps are used for industrial color judging applications, and are useful for getting a feel for toning in B&W prints and for judging color printing results.

I turn the fluorescents off in advance of loading/loading film, and a couple of minutes before taking out paper.

Lee

jp80874 · Oct 6, 2010

It is so easy to forget the potential problem when you are concentrating on something important to you. When I see a problem I get rid of it. I built my darkroom with a two tube florescent light. As soon as I became aware of this aspect of it I removed it. Why ask for trouble? Now if I could just learn to spot the problems I don’t anticipate.

John Powers

clayne · Oct 6, 2010

I wait about 2 minutes or so with paper.

Lee L · Oct 6, 2010

jp80874 said:
It is so easy to forget the potential problem when you are concentrating on something important to you.

John Powers

For me, it has become an established work habit, just like turning off the enlarger lamp before opening the enlarging paper and putting it on the baseboard, or turning out the lights before loading/unloading film, or making sure the shutter is closed before pulling the darkslide, or using the developer before the fix. My darkroom fluorescents always go off before I start setting up chemistry for developing film or printing.

The high CRI 5000K fluorescent tubes are something I got from working in commercial studios back in the early 80's.

To the OP, I'd say that if you're worried about it, test your own circumstances. You're very unlikely to find out anything really useful about your own conditions from random folks and speculation on the internet. As others have already said, there are too many variables. And apparently no one posting here so far has actually tested. I haven't.

Lee

andrewkirkby · Oct 6, 2010

Use luxeon LEDs - the ones that come in the "halogen downlight" fitting.

Cheaper to run than incandescent but also a lot cooler - and no afterglow problems like fluorescent

mgb74 · Oct 6, 2010

RalphLambrecht said:
... It's far better to get the print just right under dimmer conditions, because if lighting levels increase, so does the apparent image quality.

This is an interesting point. In small darkrooms (like the one I'm building now) it's easy to overwhelm with light - whether incandescent or fluorescent. I think I'll add a dimmer switch.

Lee L · Oct 6, 2010

andrewkirkby said:
Use luxeon LEDs - the ones that come in the "halogen downlight" fitting.

Cheaper to run than incandescent but also a lot cooler - and no afterglow problems like fluorescent

I use LED lighting in the darkroom and elsewhere, but the electronics vary. I have some LED bulbs designed for 120VAC E26/E27 sockets that have a long, easily visible afterglow (as in >2 minutes with non-dark-adapted eyes), apparently bleeding off capacitors or something along those lines, a Sylvania LED8A/F/830/350. Others go completely dark immediately, a Philips 5E26A60. I tested this recently for a friend who wanted to set up his condenser enlarger to run off his solar setup at a cabin.

Lee

Flourscent light: how long before safe in the dark?.

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