Darkroom Safelight filters (Wratten OA)

I have a big safelight that I want to mount on the wall over my sink. The Filter in it is a Kodak Wratten Series OA safelight filter --- sort of a sickly yellowy greenish grayish color. I have a 15 watt bulb in it, and it seems to be really brighter than I am used to. The filter is about 8x10 inches.

I have not been able to find a direct answer other places as to whether this is just going to fog everything, or if it is a good filter for over the sink and maybe I can turn it on after 30 seconds or a minute in the developer? Or should I just chuck it in the bin?

The OA is for graded paper only.

The OC is for multigrade paper.

THe 15 watt bulb should be fine

Don't chuck it into the bin. While it won't be good if you are using variable contrast papers, you might find some use for it, or maybe find a good home for it. These large safelight filters are expensive.

I'd be cautious about using it under any conditions with variable contrast papers. The paper is still sensitive to light while in the developer, and it might cause some fogging. What you want is an OC or equivalent safelight filter. That will be safe for most variable contrast papers. Personally, I prefer red 1A or equivalent. There are a few papers that recommend you use a red safelight, and it can be used to develop ortho films by inspection too.

To sum up, red 1A is good for graded papers, variable contrast papers, and ortho films. OC is good for the vast majority of variable contrast papers and all graded papers. OA is good for graded papers only. The 15 watt lamp will be fine, but please observe the minimum recommended distance, usually 3 to 4 feet, from the work.

You can also use a dimmer on the safelight circuit to reduce the light through an OA filter to a safe level when near unfixed variable contrast paper. A sheet or two of typing paper on the filter also cuts the light. These solutions leave you more in the dark than using the correct OC filter when using VC paper.

If you put a sheet of masking film like rubylith in with your OA filter, it should be safe. Testing will confirm that. You can always point it at a wall or ceiling to reduce the intensity.

No matter what filter or bulb wattage you end up using IMO it is important to have a reliable method for testing. Kodak suggests the following which I run about once a year: http://www.kodak.com/global/en/consumer/products/pdf/k4.pdf Takes all the guess work out of "how safe is my safelight" by telling you at what point your paper begins to fog.

richard ide said:

If you put a sheet of masking film like rubylith in with your OA filter, it should be safe. Testing will confirm that. You can always point it at a wall or ceiling to reduce the intensity.

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Let me second that. I have one safelight, which is an old, very scratched piece of plexiglas, plus a piece of rubylith, plus a home made neutral density (ND) filter. The ND filter is just fogged B&W paper. Make a test on B&W RC paper, under your enlarger, to get the correct exposure for whatever level of density you want. Fog two 8x10 sheets (most big safelights are 10x12), and tape them to the front of the plexi, with a small overlap. Or, you could just use a lamp dimmer on a standard bulb.

Like Terrence, I also have a home made safelight that has turned out to be very safe. The fixture itself is an old cast off, 5 x 7 inch safelight that needed a new lamp socket, switch, and paint job. For the filter, I used a sheet of clear glass covered with two layers of rubylith masking material. Instead of a home made ND filter, I used some Rosco ND lighting gel material which I had lying around. Instead of a 15 watt lamp, I used a 7.5 watt lamp because I use it very close to the counter where I cut larger, unexposed paper down to size. A sheet of 20 x 24 Rosco ND lighting gel costs around $6USD.