I am planning to use a spare bedroom as a temporary darkroom and would like to know if installing an extractor-fan is the best way to solve the ventilation problem. Also I know nothing about safelights and wondered if it is possible to buy a bulb that just fits into the standard light fitting. I will have to order over the 'phone and would like to know my choices. Thankyou for your time. Carol.

-- Carol S. (carfred@hotmail.com), November 29, 2001

Answers

Carol:

There are several aspects to the effectiveness of an exhaust fan. First, the fan should be located so that it draws the chemical vapors away from you, not toward you. Secondly, to be able to draw them out of the room, there will need to be some sort of vent to allow fresth air into the room. Otherwise, the exhaust fan will create a slight vacuum in the room that will reduce the effetiveness And, third the vent fan should have adequate air-flow capacity for the size room you have.

Safelights come in a number of sizes and shapes. There is one called the Sandmar Fireball that is nothing more than a very large bulb. It comes in both red (for orthochromatic films) and amber (enlarging papers). Most safelights though, are a boxed-shaped housing that accepts either a 5x7 or 8x10 (or is it 10x12?)safelight filter. Some are round and accept a 5.5 inch round safelight filter. The most commonly used filter is called an OC filter (both round and rectangular) that is compatible with both graded and variable contrast B&W papers. Color papers can be used for extremely short periods of time under a dark amber (#13?), but even with very short exposure times, there is still a risk of fogging color papers. Ilfochrome papers should be handled in complete darkness.

-- Ken Burns (kenburns@twave.net), November 29, 2001.

Another aspect of a standard style exhaust fan you may need to consider is they are not light proof. If you're intending to print during daylight hours, poke your head up in the ceiling and have a look, you may be surprised how much light is in there, depending on your roof style (eg tiled roofs generally are far from light tight!) You may need to build a light trap over the fan (cheap), or you can buy a light proof fan (expensive)

With safelights, there are domes ones that you sit on a bench or attach on the wall. They plug into a std power-point. Once you get started, read up on safe-light tests to make sure you don't fog your paper.

-- Nigel Smith (nlandgl@unite.com.au), November 29, 2001.

Carol - I set up my darkroom in a spare bedroom in my basement a few years ago and luckily the forced air furnace vent is right above the sink area. When I'm working in there I switch on the furnace blower and it works great to pump some fresh air in there, and it's filtered as well. I had read somewhere that it's better to pump the air in through a filter than to pump it out as the latter causes a vacuum in the room and sucks dust in.

-- Harv Jenkins (hjenkins@prcn.org), November 30, 2001.

Harv is correct. It is better to force air into the room through a filter, than to exhaust it. Of course, there still needs to be an exhaust vent for the air to get out of the room. That vent should be located near the sink, below face level, to draw chemical vapors away from you.

-- Chris Ellinger (chris@ellingerphoto.com), November 30, 2001.

Put in a fan if it isn't too much of a disruption. But if you spend only a few hours at a time in the room, a fan may be unnecessary. Especially if you open the door and leave the room now and then. The air may get pretty stale without a fan, but I doubt that you will take in a harmful dose of chemical fumes. I've used poorly ventilated darkrooms for many years and can identify no particular aftereffects. Although I might have more hair today had I used a fan. If you're unusually sensitive to the fumes, though, a fan is a good idea.

-- Keith Nichols (knichols1@mindspring.com), November 30, 2001.