ventilation necessary for no-smell darkroom?

[laverdure]

I use a water stop followed by a simple (thiosulphate and sulphite only) fix. Consequently, the only "chemical" smell I can smell in my darkroom is the sulfur in my tap water.

I've got a very small (new!), completely unventilated darkroom, which gets very hot in the summer. I sweat a lot. But I can spend a whole day there (8 hours or so, with breaks) without getting any kind of headache or dizziness, or at least, no more than I'd usually get from sitting still in a 92 degree room for eight hours, with breaks.

Comfort apart, how important is it for me to install a vent fan?

 

[Stephanie Brim]

And possibly a small air conditioner.

I'd say pretty important. Just because you can't smell it doesn't mean it isn't there.

 

[jp80874]

If I remember correctly Kodak says you should change the air in the room completley six times an hour. My personal view is that you should have to hang on to the sink because it is blowing or sucking so hard. If you search on this subject you will find much has already been written.

Each chemical is different. Each person reacts differently to chemicals. Many chemicals build up in your system and then one day you have a reaction and can't do this ever again.

I wear seat belts, make sure there is tread on the tires and put new pads on the brakes. It just seems like simple precautions. When there are so many ways to accidently hurt yourself, why not do the obvious.

John Powers

 

[resummerfield]

.....My personal view is that you should have to hang on to the sink because it is blowing or sucking so hard.......

I agree!

 

[Murray@uptowngallery]

Good advice (for me anyway).

Now, does alot of air flow remove dust or stir it up? (I guess that depends on whether your air intake is hooked up to the exhaust of your belt sander...

How many people have wet and dry parts of their darkroom separate with respect to ventilation?

I remember one guy saying he runs a HEPA vacuum in his darkroom a day before using the dark room to minimize airborne dust.

I see the benefit of ventilating the chemical side, but not the enlarger side...

 

[hammy]

I have just a small exhaust fan in my DR and I find that it's barely enough. I do have the exhaust hose permanently mounted into the wall and the fan itself is partially portable around the room. I place it right near my chemical trays and it seems to help a lot.

I agree that even if you don't smell it, it's good insurance to your own health.....

 

[Thomas Bertilsson]

I wouldn't worry about smell as much as the stuff you breath, odor or no odor. I have room for three 12x16 trays in my darkroom, side by side. Above the center one is a sheet metal hood, which is connected to a 4 foot piece of 8" flex duct, which in turn connnects to the darkroom wall. On that wall is mounted an 8" fan, about 1750 rpm single phase 120V motor, and that in turn has yet more flex duct hanging over towards a window. In the window frame I have hung a piece of 1/2" thick plywood, which has a backdraft flapper and an 8" hole for the exhaust.
This is the exhaust system. In order to keep a constant air volume and air pressure in the darkroom, I have several small vents attached by the floor where fresh air is sucked into my darkroom. This is underneath my enlarger stand. I don't have any odors at all, despite very pungent smells when the fan isn't running. It's not a guarantee against exposure to these chemicals, but it eliminates much of it. It's making my printing sessions much more pleasurable. I don't get fatigued so quickly. I think all of the parts ran me about $50 or so.
- Thomas

 

[Dave Miller]

Six air changes an hour will be unnoticable in terms of air flow or turbulance, and should be regarded as a minimum. The recommended rate for bathrooms/toilets is 20 per hour and you don't notice that rate either. A good supply of fresh air is essential for your health and well being.

 

[Murray@uptowngallery]

Great info all. Thanks.

 

[Richard Jepsen]

I can't imagine working in a small unvented darkroom (DR) with a temperature over 85 degrees. Surely you can find a way to move air in and out. My larger DR is also unvented but after each print I open the door to a room with the water holding tray. The developer tray can be covered and Ilford's PG or LPD developer has little to no odor. A water stop and TF-4 are a good combination for an unvented DR. That said, venting the DR is the only wise thing to do.

 

[juan]

My darkrooms are regualarly over 85F in the summer. I have my dry side in my laundry room, where the enlarger sits on top of the dryer. The wet side is my unvented bathroom. I close the door to the laundry room, make the exposure, put the print in a box and take it to the bathroom. I leave the laundry room door open. I develop and fix the print in the bathroom, then open the door. By being in the closed areas for relatively short periods, I think I am avoiding most problems. Quite frankly, with the temperature being 99F with 81% humidity this week, I think I'm in more danger of a heat stroke than chemical intoxication. I must be getting old and weak.
juan

 

[dancqu]

I use a water stop followed by a simple
(thiosulphate and sulphite only) fix. Consequently,
the only "chemical" smell I can smell in my darkroom is
the sulfur in my tap water.

I've got a very small (new!), completely unventilated darkroom, ...

Comfort apart, how important is it for me to install a vent fan?

Likely sodium thiosulfate is being used. That and sodium sulfite
are a safe combination; no fumes or odor. It's the acidification
of the sulfite which produces SO2, sulfur dioxide, and it's odor.

Personally I think ventilation concerns are over blown and an
impediment to some who other wise would have a darkroom
up and running.

A few years ago I decided I did not like the smell of vinegar
permeating the house so switched to a neutral to alkaline post
developer processing. That post processing skips the stop as
use is made of a one-shot very dilute sodium thiosulfate only
fix. The very dilute one-shot fix, BTW, yields archival levels
of fixer retained silver. Add one-shot very dilute developer
and presto-digo, one tray processing. Dan

 

[radiantdarkroom]

Wow, I am amazed that you can't smell the fix. I have never been in a lab/darkroom where I could not smell the fix. The sulfur smell is the fix. I believe you must be getting so high that you think you can't smell any chemicals. Good luck....

 

[PhotoSmith]

My view is ventilation is very important. Exposure to our processing chemicals have to have an additive impact on our bodies over the course of many years. Why not minimize it!

I installed a very quiet ventilation exhaust fan that provides 10+ air change per hour. It is important to situate it so that it draws the air away from you while you are working, not toward you. The back wall behind your sink is a great place. On the opposite wall I installed two flat air difussors that are designed to fit on an ordinary forced air ventilation duct. One is placed low on the wall in the opposite room. The other is placed high on the darkroom side of the wall. I painted the inside surface of the studs and drywall with flat black paint, in essence creating a light baffle. Then attach a small fiberglass furnace type air filter over the vent in the darkroom to keep dust down. The whole thing can be done for $100 - $200. depending on how extravagant you get with the fan.

Your health is worth it, and it should provide some relief to the extreme temperatures you are experiencing!

 

[jp80874]

Personally I think ventilation concerns are over blown and an
impediment to some who other wise would have a darkroom
up and running. Dan

Dan,

The only thing I can agree with is that the darkroom should be over blown, hyperventilated, I mean a breath of fresh air.

Here are some earlier threads on the same subject where others and I blew off on how we think a darkroom should be ventilated.

(there was a url link here which no longer exists)

(there was a url link here which no longer exists)

Just to add to the point of taking practical precautions, let me say that since I posted this yesterday,” I wear seat belts, make sure there is tread on the tires and put new pads on the brakes. It just seems like simple precautions. When there are so many ways to accidentally hurt yourself, why not do the obvious.” I have spent four hours in the emergency room of a hospital, seventy miles from home, last night with a friend of thirty years who hadn’t taken some of those precautions. My wife and I happened to be with he and his wife when he got sick, threw up, passed out, and almost bit his wife’s finger off as she tried to clear the airways. Unexpected sh-t happens, why not prepare for the stuff that you can anticipate? We did drive them home after the event, only to find our dog had torn apart the kitchen from having been left so long unfed and unwalked.

John Powers

 

[laverdure]

"Likely sodium thiosulfate is being used. That and sodium sulfite
are a safe combination; no fumes or odor."
yes.

By the way this question is mostly theoretical. Even in the fall I'll want a fan to relieve the stuffiness. And I do tend to wear seatbelts when they're available. But I still think it's a valid and interesting question: whether there is anything dangerous in the fumes of darkroom chemicals that don't give off any odor. I've heard Kodak says you should burn your shoes if you spill any KRST on them. But what if it's just a few drops? And very dilute?

Sodium sulphite is a food preservative; sodium thiosulphate is a municipal (and swimming pool) water additive. Which is not to say that they're harmless at high concentrations, but I think it's fair to say a little won't hurt you much. You're going to get much more of a nosefull of sodium thiosulphate going to the pool than you are in my darkroom, I expect. Never mind chlorine. Especially if you get dunked.

Given my system that leaves developers. They don't seem to smell like much. At least, the ones I've bothered to sniff at. Do some smell more than others? Do some give off more harmful fumes than others? Is there any correlation? I'm curious.

 

[Dave Miller]

I am more concerned that I maintain an adequate oxygen level than that I remove fumes, however if I worked with open trays, as I believe most do, then fume removal would become equally important.

 

[tommy5c]

This is a great thread, especially for me right now. I'm in the process of building my darkroom. and i know i need ventilation. I myself cannot smell most of the chemicals in the darkroom (years of repeated exposure to much worse I'm sure) But i don't want to take any chances for either myself or my family. I was planning on adding two fans (bathroom ventilation type) above the sink. but this thread is making me think. should i mount them on the ceiling or on the wall , like at a 45 degree angle. on the wall is more difficult, but if the wall will make a considerable difference I'll put them there.

 

[Dave Miller]

Another point to bear in mind with regard to fans is that of noise. If possible mount the fan(s) remotely and duct the air to and from it.

 

[Monophoto]

Another point to bear in mind with regard to fans is that of noise. If possible mount the fan(s) remotely and duct the air to and from it.

Dave's point is very important - if the fan is so noisy that you can't think, you won't use it.

My ventilation system is based on a computer-style muffin fan. These are inherently quiet, but I've also mounted it completely outside the darkroom. I used some of the plastic ducting material used for bathroom ventilation systems to connect the fan to a louver inside the darkroom. The result is so quiet that I don't even know its on.

The other suggestion is that the ideal ventilation system is a positive pressure system. You can get by with a fan that pulls stale air out of the darkroom (negative pressure) but that system also causes air to flow into the darkroom through all of the unavoidable nooks and cracks - under the door, around receptacles, etc, and since you can't seal or filter those entry points, you will get more dust in the darkroom. With a positive pressure system, you control how air enters the darkroom, and can put a filter on it to eliminate dust.

 

[PhotoSmith]

You should be able to find a very quiet fan. I have seen "whisper quiet" type bathroom ventilation fans at home building supply stores. I purchased a larger exhaust fan from Grainger which is a large industrial supply store.

I had never considered the positive pressure system. It sounds like an interesting way to ventilate. I think it is definitely worth looking at.

 

[PhotoSmith]

This is a great thread, especially for me right now. I'm in the process of building my darkroom. and i know i need ventilation. I myself cannot smell most of the chemicals in the darkroom (years of repeated exposure to much worse I'm sure) But i don't want to take any chances for either myself or my family. I was planning on adding two fans (bathroom ventilation type) above the sink. but this thread is making me think. should i mount them on the ceiling or on the wall , like at a 45 degree angle. on the wall is more difficult, but if the wall will make a considerable difference I'll put them there.

I think the wall behind the sink would be ideal if you can manage it, or the side walls adjacent to your sink. If you use Dave's suggestion and locate the fan motor remotely, it would only take a couple of strategically placed vents to accomplish this. Good luck.

Unfortunately, I had to leave my darkroom behind when I moved, so I'm in the same boat as I build a new darkroom.

 

[resummerfield]

I calculated the volume of the darkroom in cubic feet, then doubled the number to account for losses in fan mounting, position, and ducting. I multiplied this volume by 6 to allow 6 air changes per hour. Convert this to minutes (divide by 60) and that will be the required volume of your fan, in Cubic Feet per Minute. My darkroom required a 400 CFM fan, but I bought a 900 CFM model and used a dimmer control to reduce the airflow (and noise) for certain operations.

I set-up one complete system over my sink to exhaust to outside, and another similar system on an interior wall to bring conditioned air into the darkroom to pressurize the darkroom. I generally run the exhaust system only, as the pressure only system seems (in my set-up) to be less efficient. But for noxious smells like toning, I can run both systems at maximum.

I agree completely with John Powers, that “the darkroom should be over blown, hyperventilated, I mean a breath of fresh air.”

 

[GFDarlington]

My darkroom is also very small but its in a house with 40" thick sandstone walls and no windows, so I haven't considered installing any sort of ducted ventilation system so far. I use a Nova upright processing system and so there don't seem to be a huge amount of fumes around but I was wondering if anyone has any experience of using the Filtair type of filtered system rather than an expelling of ioniser type system? They seem pretty expensive new but I'd like to know how well they work and whether they might represent a good alternative in my particular situation?
Graham

 

[Dave Miller]

My darkroom is also very small but its in a house with 40" thick sandstone walls and no windows, so I haven't considered installing any sort of ducted ventilation system so far. I use a Nova upright processing system and so there don't seem to be a huge amount of fumes around but I was wondering if anyone has any experience of using the Filtair type of filtered system rather than an expelling of ioniser type system? They seem pretty expensive new but I'd like to know how well they work and whether they might represent a good alternative in my particular situation?
Graham

Tim Rudman uses these I think.