New darkroom !

Hi, I am just about to build a new garage and at the back I am going to build a darkroom 1.8m x 3.2m. My previous darkroom was a cellar that I shared with my wife who used it as an ironing room! (I would regularly have to iron some shirts before I could use it!)

 

So couple of questions:

 

(1) Safelights - in my previous darkroom I used Paterson lamps that were fixed to the wall. But I have wondered about using red LEDs in the ceiling on a two way switch with white ones. Is this sensible and has anyone any experience of using red LEDs in a darkroom

 

(2) Ventilation - planning just to have a light proof grill in the door and then an extractor fan above the wet bench. Would this be work.

 

Glad for any feedback and I can't wait to get back to printing again

 

David

Red safelight was what we used many many years ago.to develop orthochromatic film. This was film sensitive to blue and green but not red. Todays films are panchromatic, sensitive to red, green and blue. No safelight is unusually used however a dim green can be used to keep you from tripping. A dim green can be used for a few seconds to inspect the film mid process. Wet film is less sensitive than dry film. As to photo papers, we switched amber in the 1950's. Todays multi-grade and sensitive to blue and green and require a special safelight. What I am saying is, buy a photo grade safelight designed for the materials you will be working with. Why experiment and likely experience a learning curve longer than you think?

I put film into processing reels in a changing bag in the light. Only want a safe light for printing black and white paper

I put film into processing reels in a changing bag in the light. Only want a safe light for printing black and white paper

Amber safelight is best for todays papers.

If at all possible, wire the main/safelight changeover to a pull cord run horizontally across the room just above head height.

 

Makes it very easy to find in the dark.

 

We had this setup in our university darkroom, two pull switches with their cords tied together. Pull one way to turn lights on or off, the other to toggle between safelight and white light.

 

Beats stumbling around looking for a light switch.

Red LEDs are almost monochromatic, and far 'safer' than any filter that can be economically made.

 

A typical red LED emits in a narrow (50nm) band peaking at 630nm. This would be totally safe for VC paper and other Orthochromatic materials.

 

However, you might want to consider the addition of amber LEDs as well, for a visually brighter light.

 

The 'brightest' commercial safelights used low-pressure sodium vapour lamps, which are also near-monochromatic. They were also very expensive. Sodium emits at two monochromatic lines centred on 590nm.

 

Common amber LEDs have a peak emmission at around 595nm, and again have a spread of about 50nm, with the emission at 550nm being almost insignificant.

 

550nm is the cutoff point of Ilford Multigrade paper sensitivity, according to Iford's datasheet.

 

Some typical spectra for a range of LEDs are given here. But it would be wise to get the exact specification for a particular component before committing to anything.

Edited September 26, 2020 by rodeo_joe|1

There are commercial LED safelights, but probably expensive.

 

You can easily find colored replacements for incandescent lamps in colors,

though finding the spectra for them might be harder.

 

Note that for Polycontrast, Kodak says use OC not OA.

They are both yellowish.

 

Note that especially for yellow, looks are not a good way to judge by eye.

 

A yellow light could be the sodium lines at 589.0 and 589.6 nm,

or it could be a mix of green and red. The former is good for variable

contrast paper, the latter might not be.

 

It used to be that one bought individual LED lamp units, wired them up

with a series current limiting resistor, and all was fine. That was before they

made them as incandescent replacements.

Any thoughts about ventilation?

Any thoughts about ventilation?

You definitely want a good exhaust fan and a way to bring in fresh air to make up for the air pulled out by the fan. I'm not sure what is still on the market, but there used to be a number of exhaust fans and vents that came with light baffles.

My darkroom, built by the previous house owner, has a somewhat big fan. I have never used it.

 

The main darkroom chemical with a high vapor pressure is acetic acid stop bath.

But to me, at least at the concentrations I have been in, it is partly what makes

it feel like an actual darkroom. That is, the nostalgic smell of darkrooms.

 

I suppose at higher temperatures it increases, maybe enough that I would want a fan on.

 

I suspect though, that when I am actually using the darkroom, that I open the door often enough

to get new air in.

If you replace an acetic acid stop bath with citric acid there'll be no smell at all!

 

I'm not sure how acetic acid ever got to be the smelly 'standard' for a stop bath. Maybe the Victorians just liked the smell of vinegar?

 

Sodium or potassium metabisulphite solution would probably work just as well too.

In my early newspaper days the darkroom smelled more like cigar smoke than anything else and it was like working in a fog bank but we got it done. If you have a decent air conditioner the fumes usually aren’t bad. My darkroom now is equipped with all the gear that went surplus at an old job. If you don’t use acetic acid you’ll be fine.

 

Rick H.

If an extractor fan is an exhaust fan, NO,NO,NO. You will be sucking in unfiltered air from the garage . You need an inlet fan that can be fitted with a filter.

None of my 3 darkrooms had an exhaust fan. That was never an issue processing B&W films or paper. I only did color in the largest darkroom, that was a bit of a problem, but since the darkroom was at the side of a dark garage, I was able to open the door for ventilation. Would have been nice, but neither the buildings nor the budget were up to installing a proper system. Since you are building from scratch, you can certainly add proper ventilation. B&H and others have purpose designed units worth considering.

You definitely want a good exhaust fan and a way to bring in fresh air to make up for the air pulled out by the fan. I'm not sure what is still on the market, but there used to be a number of exhaust fans and vents that came with light baffles.

 

You don't need an exhaust fan, ;you need an intake fan (to pressurize the darkroom).

 

Those are readily available. better and more cheaply than photo products from commercial hardware stores. Installed a 12" over my girlfriend's ceramics kiln. Ceramic projects don't require dark.

 

Most importantly IMO, you need linoleum floor that you can mop.

Tip-1, paint the walls and ceiling WHITE, and use a white/light colored floor covering. This reflects the light from the safelight, so you don't need as many safelights, you don't have dark corners, and is much more pleasant to work in. The first time I saw a light painted darkroom, I was a convert, and painted mine white.

But paint around the enlarger with flat black paint, to kill any stray reflections from the enlarger.

 

Tip-2. I put the switch for the WHITE light in it's own switch box, up near the ceiling. This made it DIFFICULT to "accidentally" turn on the white light.

I've seen Murphy strike several times, when someone "accidentally" turned on the white light when a box of paper was open. :eek:

If the switch for the white light is next to the switch for the safelight, it should have a safety cover over it, to prevent accidentally turning on the white light.

 

I agree about the need to filter the incoming air. Garages tend to be dusty and dirty. Mine is. When the door opens, the wind blows the dust, dirt and leaves into the garage.

Put the intake side of the darkroom ventilation high, maybe head height. That will reduce the intake of dust from the garage floor.

 

You could use two fans.

• #1 intake fan of a higher flow rate than the exhaust fan. Put this behind the filter, or at least behind a pre-filter, so the air is filtered before it reaches the fan. An unfiltered fan blades and motor will gradually get dirty. Some fans are really hard to clean. Note that the actual flow rate will be reduced by the filter.
  The door should also be sealed, so dusty air won't flow around the door into the darkroom.
  

• #2 the exhaust fan over the sink, where the chemical trays will be.
  

I used two 16' lengths of deep red LED strips from Superbright LED's in my darkroom. They are on a dimmer and I tested them at 1/2 power to 25 minutes before any fog started to show up. I generally use them at 1/3rd power so I am pretty good for darkroom lights, they are bright even at 1/3rd. One strand is in a semi-translucent tubing above the enlarger stations and the other along the 9' foot sink for my trays, ends up in the corner in the film processing area above the 6' foot sink.

 

For ventilation I use two fans, a pusher at the top of the stairwell going to the basement with a filter on it and then an exhaust that pulls directly from the 9' foot sink and doubles as a shelf. It works fantastic, even with 20x24 trays full of chemistry, I never even smell the fixer. This is a full tilt fine art darkroom in which I can process 35mm to 8x10 and print up to 4x5 in sizes up to 45" x 55" using a mural paper processor. You can see in the enlarger station photo showing the rope light that the center enlarger prints ceiling to floor.

 

Here are some pics at various stages, it is much more complete now: