How dark should a darkroom be?

fotch · Jan 9, 2010

Black is black. I think of a darkroom as the inside of a camera. Would any level of light leak be acceptable? A changing bag for loading film in a daylight processing tank would be safest if the darkroom is not 100% dark.

As others have said, this may eliminate the ability to do some things like tray process. I myself always try for perfection even though its seldom achieved.

So, "Don't slack, make it Black" . It is not that hard to do and you only have to do it once.

JMHO

2F/2F · Jan 9, 2010

One trick to use when jury rigging a darkroom is the application of rubylith masking film to windows and other light sources that you cannot permanently block. Rubylith film is basically just a large filter that blocks the wavelengths to which your photo paper is sensitive. For instance, I have a small window in the basement where my darkroom is. It would be easy enough to board over it...but it is not my house, so I cannot. Also, it is nice sometimes to not completely block out a light source, but to simply filter it and use it as a safelight. What I did is to coat a pane of Plexiglass with it to make a giant filter, and I wedge this against the window. You can also apply the rubylith directly to a window, if it is your house. I also stuff cracks with aluminum foil. It is cheap, easily formable, and does not require any adhesive.

keithwms · Jan 9, 2010

RalphLambrecht said:
Me too, as long as it is not an excuse to avoid learning and understanding, which eliminates so many unnecessary problems. Let's not confuse serendipity with creativity.

I agree, of course. One must learn what matters and what does not.

~~~

When I started b&w, I obsessed over every millidram of each chemical, the temps, vacuuming my bottles etc. Over time I started to sort the technical issues into things that matter a lot, things that matter, and things that don't matter at all... and started to spend time on the former. The whole process then became far more enjoyable.

FWIW I can offer an analogy to sculling, which I used to teach quite regularly. A beginner reluctantly gets into that little scull, has a death grip on the oars and every little ripple throws them into a mad panic. 99% of the coaching boils down to convincing them that the scull wants to stay upright, the water wants to carry them on, and any instability in the rig comes from them and their nervous reactions. So too photography: it's easy to sort out what matters and what doesn't, and if one has an attitude of fretting over the things that ultimately don't matter, then the whole process is less enjoyable. Some people have a remarkable ability to find problems where none exist.

So again, all I am saying is: there are a whole lot of variables at play in the whole process. Perhaps too many to count. If one obsesses over each and every one then one simply won't have time to clear your head and think as freely and creatively as one could.

One could of course say that you might have extra base fog from some minor light leak in your darkroom. But "might" isn't good enough, if you think it's an issue then check it out, it'll take no more than a few minutes to develop a test strip and see. I am not saying take it on faith, I am saying you know damn well how to find out if it matters, so just do it and move on.

removed-user-1 · Jan 9, 2010

RalphLambrecht said:
The whole entrance is designed as a light trap. You walk around a double corner in which the walls are painted flat black. It is open and yet light tight, which is great for a teaching darkroom where people can go in and out without disturbing the session.

Central Piedmont Community College in Charlotte had the same arrangement (I haven't been in their darkroom in ten years so this may no longer be true). I prefer this to the revolving doors that we had at Delmar and Appalachian State because those often resulted in unexpected collisions.

jp80874 · Jan 9, 2010

fotch said:
Black is black. I think of a darkroom as the inside of a camera. Would any level of light leak be acceptable? A changing bag for loading film in a daylight processing tank would be safest if the darkroom is not 100% dark.

As others have said, this may eliminate the ability to do some things like tray process. I myself always try for perfection even though its seldom achieved.

So, "Don't slack, make it Black" . It is not that hard to do and you only have to do it once.

JMHO

...or what part of dark do you not understand?

I would also suggest a furnace filter built into the intake for the room. Everywhere light can leak in (with the exception of a window) dust can follow especially if there is suction. Dust, pet hair, etc. do not make for pretty negatives or prints.

John Powers

Jesper · Jan 9, 2010

If you want to make the windows lightproof (a strange state for a window) you can put some aluminiun foil between the window panes.
It is quickly done and metal foil is 100% light proof.

Monophoto · Jan 9, 2010

In my experience, the major issue is sealing around the door. The solution I found involved two things.

First, I used oversized door stop. Instead of using the standard, pre-milled moldings from the home center, I cut lengths of clear pine to use as door stop, and made them about twice the standard thickness.

Second, I applied a strip of felt weatherstripping to the door stop. I chose felt because the rough surface means that it won't reflect light - foam weatherstripping has a smooth surface and is reflective.

My darkroom is in my basement, and if I leave the light on in the space just outside the darkroom door, I can see a faint glow at the edge of the door stop after the lights have been off for several minutes. I've learned to simply leave that light off.

I used a suspended ceiling in my darkroom, and I've noticed that there is also a slight leak around the perimeter of the ceiling if that exterior light is left on. It is strange because there is no straight-line path from the light to the point where the ceiling joins the darkroom wall - apparently, light is able to bounce around enough to create just a hint of a glow in a couple of places around the perimeter.

When I am reloading film holders, I stand with my back to the door and also the area where the light leaks around the ceiling perimeter - shielding the film with my body from the leaks. But I can't do that when processing film - but after processing several hundred sheets of film, I haven't been able to detect any sign of fogging.

RalphLambrecht · Jan 9, 2010

Monophoto said:
In my experience, the major issue is sealing around the door. The solution I found involved two things.

First, I used oversized door stop. Instead of using the standard, pre-milled moldings from the home center, I cut lengths of clear pine to use as door stop, and made them about twice the standard thickness.

Second, I applied a strip of felt weatherstripping to the door stop. I chose felt because the rough surface means that it won't reflect light - foam weatherstripping has a smooth surface and is reflective...

I attached pictures of my light-trap solution in post #15. No seal, felt, tape, foam or any kind of weatherstripping required. I went through all of that until this simple solution was pointed out to me. It's 100% light proof and does not interfere with the functionality or the closing efforts of the door.

jp80874 · Jan 9, 2010

You may have some things in the darkroom that give off light that needs to be controled if loading film. My timer and thermometer have markings that glow in the dark. Some equipment has led light indicating that it turned on.

John

MattKing · Jan 9, 2010

I find that a dark towel dropped on the floor and pushed up against the door does a good job of blocking the light that can sneak through there. I just get into the habit of adjusting it each time I use the door.

I've wondered about this "Twin Draft Guard" instead:

http://www.asseenontvguys.com/index.asp?PageAction=VIEWPROD&ProdID=349

Matt

BetterSense · Jan 9, 2010

I use the towel method as well, when I am loading film in there and it's light out.

Jerry Thirsty · Jan 9, 2010

I do something similar to what the OP is suggesting. I have an open, unfinished basement about 20ft x 30ft and have all my tables and equipment set up in one corner. I have homemade wooden shutters attached to the tops of the window frames with hinges (inside the basement, not outside), and at night I can just flip them down and they do a good enough job. I also have a door at the top of the stairs to the rest of the house that I just leave open; it's perpendicular to the stairs so even if a car should drive by or something very little light can actually reflect down the stairs. I don't use an active ventilation system at all. The only chemical I've got that produces any noticeable fumes is fresh-mixed TF4, with the slight ammonia smell, but that disappears after a couple of uses. Maybe the volume of the space, coupled with the open door is enough to keep it from getting stuffy, IDK, it's just never been a problem for me.

I seem to remember back when I was getting started that the rule of thumb was: Sit in the darkroom for 5 minutes with no safelight on to let your eyes adapt, and if you can't see your hand when you put it up in front of your face then it is dark enough.

nickandre · Jan 9, 2010

I have printed color prints (which is much more sensitive than b+w paper) in light where I could see fairly well with all lights off and had no problems. Just don't leave any paper out and you should be fine.

Necator · Jan 10, 2010

This is one of the things I like about APUG. You ask a beginners question, and still get tons of opinions and hints. All in all, it sounds like I can use my basement room after all. I wanted to install a bathroom fan anyway, and the instructions on how to build light traps seems to be straightforward. I will still use my changing bag for working with film, just in case. On that subject, I remember a scene in BBC's Genius of Photography where Tony Vaccaro explains how he developed film in a set of helmets during WW2. No darkroom, no changing bag, just waited for darkness. But that was probably not 400 ASA film back then

RalphLambrecht · Jan 10, 2010

Necator said:
This is one of the things I like about APUG. You ask a beginners question, and still get tons of opinions and hints. All in all, it sounds like I can use my basement room after all. I wanted to install a bathroom fan anyway, and the instructions on how to build light traps seems to be straightforward. I will still use my changing bag for working with film, just in case. On that subject, I remember a scene in BBC's Genius of Photography where Tony Vaccaro explains how he developed film in a set of helmets during WW2. No darkroom, no changing bag, just waited for darkness. But that was probably not 400 ASA film back then

Very good. If your highlights end up not quite as brilliant as you like them, and your pictures remind you of battleship gray, you know where to look first. I wish you all the best and welcome to the dark side.

Jesper · Jan 10, 2010

If you are worried about light in your darkroom, just leave a paper out for a while with something covering part of it.
Leave it for an hour and develop it. If there is a difference between the two parts you have a leak (that may or may not be a problem).
If you can 't tell where it was covered everything is OK.

APUG is a wonderful place.

RalphLambrecht · Jan 10, 2010

Jesper said:
If you are worried about light in your darkroom, just leave a paper out for a while with something covering part of it.
Leave it for an hour and develop it. If there is a difference between the two parts you have a leak (that may or may not be a problem).
If you can 't tell where it was covered everything is OK.

APUG is a wonderful place.

Sorry, but this is not an entirely valid test. It ignores the threshold exposure paper needs to develop density. A slight modification makes this test much more sensitive and also more realistic.

Expose the paper to what would develop to a light gray (threshold exposure) but don;t develop it yet, then leave it out with an opaque object placed on top of it for your maximum handling plus processing time (let's say) 10-15 minutes and process the paper normally.

If you can't see any tell-tale signs of the object, now everything is OK.

Jesper · Jan 10, 2010

The threshold is the reason for the extended time (one hour).
In order to change state you need a certain number of photons of at least a certain level of energy (I am not going into exact numbers it varies between different materials).

Let us say that you need ten units to change. That means that even though you have received nine nothing will be visible.
This we perceive as the threshold.
This is why you sometimes may need to preexpose film and paper but that is another story.

In order to test the darkroom you can either, as Ralph suggests, use a prexposed paper and a shorter time or an unexposed paper for a long time. As long as the number of photons with the right energy is received there will be a change of state. With a preexposed paper you can take the level to nine and leave it out to see if it reaches number ten, or you can leave it out for a prolonged time starting at 0 to see if it reaches ten.

There are a lot of methods, and most of them works.

RalphLambrecht · Jan 10, 2010

Jesper said:
The threshold is the reason for the extended time (one hour).
In order to change state you need a certain number of photons of at least a certain level of energy (I am not going into exact numbers it varies between different materials).

Let us say that you need ten units to change. That means that even though you have received nine nothing will be visible.
This we perceive as the threshold.
This is why you sometimes may need to preexpose film and paper but that is another story.

In order to test the darkroom you can either, as Ralph suggests, use a prexposed paper and a shorter time or an unexposed paper for a long time. As long as the number of photons with the right energy is received there will be a change of state. With a preexposed paper you can take the level to nine and leave it out to see if it reaches number ten, or you can leave it out for a prolonged time starting at 0 to see if it reaches ten.

There are a lot of methods, and most of them works.

Are you considering the latency effect? This is not always a simple addition of photons. If your ten-photon minium was applied over too long of a time, some of their energy has already dissipated. A small initial preexposure is a more robust way to detect small additional exposures, in my opinion.

Jesper · Jan 10, 2010

And that is why I tried to use "level" instead of photons.

RalphLambrecht · Jan 10, 2010

Jesper said:
And that is why I tried to use "level" instead of photons.

Jesper

My point is, very dim ambient lighting may be sufficiently weak to never create and exposure by itself. However, when added to the normal print exposure, it may increase print densities. To capture this fact, any safelight test must include a small pre-exposure, otherwise, it is unrealistic and may not show the detrimental effect of bad safelights, light leaks etc.

fotch · Jan 10, 2010

Ralph, would this test be sensitive enough for film? Or should the test be done with film?

RalphLambrecht · Jan 10, 2010

fotch said:
Ralph, would this test be sensitive enough for film? Or should the test be done with film?

Yes, but with film, I would expose the film in-camera to a Zone II (average measurement - 3 stops) and take it into the all-lights-off darkroom for 1/2 hour, while covering the film partially with an opaque object. Then develop normally and see if you see a difference. If not, the darkroom is sufficiently sealed against light leaks and safe for processing film in a tray.

jp498 · Jan 10, 2010

I have a curtainrod over the door, and pull a homemade black felt curtain past the door. It is extra long and drags along the floor a little, stopping light from coming in from the bottom, top, or sides of the door.

It may not be necessary, but I also throw a towel over my gralab timer, as the numbers glow on it.

Never had a problem with light damaged film or paper.

Sirius Glass · Jan 11, 2010

I put velco on the top of the door jam, on the outside of the door, and a strip of matching velcro on the blackout cloth to keep light from getting through the door.

I put velco above the window, down the sides and on the bottom to hold the blackout cloth in my dry darkroom.

For the wet darkroom, a large bathroom, I have a piece of wood with two hand grips and that is cut to the shape of the window. The wood has a much larger piece of blackout cloth attached to it. I place the wood with the blackout cloth into the window frame and use tape to attach the cloth to the walls.

Steve

How dark should a darkroom be?

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