Safelight Bulbs

[geauxpez]

I recently was given a nearly complete darkroom setup by a friend that included a "Yankee Safelight SL-2". On the label, it says "110 volt 15 watt". The bulb that was in it was a Sylvania NO. 140 75w-120v and it seems to get awfully hot awfully quickly. I bought a compact florescent 19w 120v bulb (supposedly equivalent to a 75 watt incandescent bulb) to replace it (and hopefully run cooler). Any ideas or suggestions?

Thanks,

Adam

 

[Kilgallb]

Do not use a 75 watt lamp in a 19 Watt enclosure. It is a definate fire hazard.

Do not use a fluorescent lamp in a dark room. They glow in the dark, which can fog your film.

Buy the proper lamp. The 75 watt lamp will fog your paper.

 

[Gerald Koch]

Even though a fluorescent bulb may be rated at only a fraction of the wattage of the bulb it replaces and the incandescent bulb happily worked in a confined space, I have found that being in the confined space severely limits the life of the fluorescent bulb. Evidently the electronics in the base needs plenty of air circulation.

 

[raucousimages]

Just us ea 15W bulb, problem solved. If you can't find one at a hardware store try a lighting store, they will have them.

 

[Nick Zentena]

Isn't 15 watts just an appliance bulb?

 

[srs5694]

You could also ditch the safelight filter and substitute a red or amber LED bulb. I've not tried this approach, but there have been some threads here on LED safelighting recently, and it seems like a reasonable and energy-efficient way to go (not that a single 15W incandescent bulb is a huge energy hog, but every little bit helps).

As to fogging and wattage, most safelights use low-wattage bulbs and include instructions to keep them at least a certain distance from the paper (usually about 3-4 feet, IIRC). It's conceivable that a 75W bulb would be OK if kept much further away than that; you'd need to do some tests to be sure. Similar comments apply to using a 19W fluorescent bulb -- fluorescents put out more lumens per watt than do incandescent bulbs. I wouldn't worry about fluorescents fogging B&W paper if the fluorescent is used in a safelight with a proper filter; after all, the point of the filter and light-tight enclosure is to prevent light getting out except for light that's safe to the paper. Fluorescents fogging paper is an effect of the bulb continuing to glow when the light is turned off. This is an issue for normal room lighting, but in a safelight it's a non-issue, unless perhaps you turn on the safelight and then turn it off to handle film or color paper.

 

[Monophoto]

Adam -

The 15W rating implies two things:
1. The light output (measured in lumens) is less than that of a 15W incandescent lamp. Using a bulb that is any brighter than that has the potential of causing fogging.
2. The electrical design of the fixture assumes that the power consumption of the bulb will be 15W or less, and using an incandescent bulb that consumes more could cause overheating and possible fire.

Substituting a standard off-the-shelf-at Home-Depot CFL for an incandescent bulb may get around the second limitation, but the light output of a CFL will be greater than the light output of an incandescent bulb of the same rating. So you will still have the first problem - potential fogging. If you do some shopping on-line, you can probably find CFLs with much lower lumen output ratings that you could use if you prefer that kind of light source.

There are two situations that favor using CFLs -
1. Energy consumption per lumen of light output is much higher than with incandescent bulbs. This is significant in instances in which the light will be on for extended periods.
2. The life expectancy of a CFL is considerably longer than with incandescent bulbs. This is significant when replacing bulbs is either inconvenient or has an unacceptable cost - for example, in commercial applications where they have to pay someone to screw in new bulbs, or on those fixtures at home that require that you get on a tall ladder to replace the bulb.

In my opinion, a darkroom safelight doesn't fit either case, so I suggest sticking with an inexpensive appliance bulb.

 

[geauxpez]

Thanks guys. I am now wondering if that 75w bulb was actually a spare enlarger lamp bulb placed in the safelight to keep it from getting broken. Who knows. I'm glad I didn't actually use the 75 (or the CFL for that matter). I'm still in the "getting it all together" stage.

Thanks again for the replies & explanations.

 

[Kilgallb]

A flourescent lamp will fog panchromatic materials such as Tri-X film. They glow in the dark after the power is off. They can even absorb photons from the other lamps in the darkroom and glow. Kind off like the luminous dial on a Gra-lab timer.

 

[raucousimages]

We (Lowes) sold appliance bulbs in 15, 25, 40 and 50 watt if I remember right but seemed to always be out of 15.

 

[dancqu]

I've two round plastic Yankee SL-3s. One has a 7.5
and the other a 15 watt. I think there is a 5 watt some
where about. I double filter and use low wattage for
tight area lighting. Dan

 

[Jim Jones]

15 W bulbs sometimes show up in household goods departments. That's where I had to buy mine. Hardware stores should have 7.5 W bulbs, but they are ridiculously expensive. Low wattage incandescent bulbs are fragile. In safelights I use little bulb savers, which are a diode mounted in a disc that fits on the bottom of the bulb and cuts the voltage down to half. It cuts the light down too, but mostly in the blue end of the spectrum that the safelight filter blocks anyhow. The bulbs last almost forever on half voltage.

 

[geauxpez]

Good to know Jim. Where would one find something like that?

 

[Troy Hamon]

I have installed LED safelights in my darkroom and they work great. So far I've only used the red ones, so don't know about the amber, but I have very bright (relatively speaking) safelights and have been totally unable to detect any fogging in my safelight tests.

I also have one of the old safelights that takes a 15W bulb. The bulb was burned out, so I got an extra red LED bulb and took off the front amber filter from the safelight. It works well, and is as bright or slightly brighter than the safelight with a normal bulb. The LED bulb draws 3W.

Happy Thursday.

 

[Justin Low]

I too, use LEDs. They work great. No fogging at 10 minutes. I built my own with the help of a friend. It runs on a pair of D-cells and they last about a year.

We're currently working on a second model. Considering marketing it commercially if there's a demand.

 

[grahamp]

Exceeding the designed light output in a safelight is going to have a few effects in the longer term. If it is incandescent then the heat can damage the fixtures. The greater light output will not be as safe at usual distances. Finally the stronger lamp will accellerate the fading of the filter. None of these may be immediately apparent.

I have been running a couple of old UK Paterson safelights on US voltage with the original bulbs for a few years now. Dim, but usable with the orange dome. I recently converted one to use a candelabra bulb of matching wattage at US voltage. Much brighter, and replacements are readily available at the local hardware store. I can use the red dome now Personally, I like as much (but no more) 'safe' light as the process and timings will permit.

 

[Jim Jones]

. . . In safelights I use little bulb savers, which are a diode mounted in a disc that fits on the bottom of the bulb and cuts the voltage down to half. It cuts the light down too, but mostly in the blue end of the spectrum that the safelight filter blocks anyhow. The bulbs last almost forever on half voltage.

I believe the last of my bulb savers came from a hardware store.

 

[geauxpez]

Thanks again guys. I was unable to find 15w bulbs at Home Depot, but a small local hardware store had them -- 3.99 for 2. I have rigged a bracket for my light housing to point it towrd the ceiling & disperse the light a bit more.

Taking a hint from Justin (above), I may tinker with making an LED safelight. Costs too much otherwise.

 

[Steve Smith]

I use little bulb savers, which are a diode mounted in a disc that fits on the bottom of the bulb and cuts the voltage down to half. It cuts the light down too, but mostly in the blue end of the spectrum that the safelight filter blocks anyhow. The bulbs last almost forever on half voltage.

Another option for half voltage is to run two identical lamps in series. Or if a 230 volt lamp is available in the US (or could be ordered from UK or Europe), run it on 110 volts.

Steve.

 

[Jim Jones]

Another option for half voltage is to run two identical lamps in series. Or if a 230 volt lamp is available in the US (or could be ordered from UK or Europe), run it on 110 volts.

Steve.

Great idea. One way of doing this is to assemble a power cord, an outlet box, and a duplex outlet with the outlets connected in series. I have a 40W and 60W lamp in series for a night light. The 40W lamps last for several years of continuous use. I don't expect to ever have to replace the 60W lamp, which emits very little light.

For anyone with modest electrical ability, a diode can be hardwired into a safelight fixture to halve the voltage. This is much cheaper than the lamp savers I usually use. My main safelight is controlled by a dimmer, which is even better.