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What should I look for in a respirator for chemical processing of photographic materials?

I am already wearing eye and skin protection when using development chemicals.

I would like to avoid breathing in irritants and toxic chemicals.

The answers Google turns up are mostly forum threads dominated by "real men don’t use a respirator" type comments that don’t shine light on considerations regarding respirators themselves.

A person can use a respirator and ventilation. Indeed a person may need or want both. Needs might be due to allergy or heightened sensitivity. Needs might be based on using an alternative process such as collodion or daguerreotype.

A want might be to develop habits normalizing respirator use should future work involve more toxic chemicals. In other words to have a methodology that can maintain consistency in new situations.

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  • Which chemicals are you / will you be using? Are you using any powders? Is your ventilation adequate? Are you mixing or transferring near a ventilation exhaust, or hood?
    – scottbb
    Apr 22 at 16:28
  • If you have an allergy to a particular chemical, you should consult with a physician. We can’t provide medical advice.
    – Tim
    Apr 25 at 8:48
  • @Tim No need for medical advice. A respirator might completely avoid the discovery of a previously unknown allergy. Apr 25 at 12:35
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+150

Note that the only real question here is half-face (mouth/nose) vs full-face (also the eyes), and for full-face respirators some are more friendly to glasses than others are. If you are in a situation where the respirator itself matters you need a lot more than a respirator!

What you actually care about is the filters that you attach to the respirator. There are a bunch of different cartridges you can buy--all cover particles down to a pretty small size, some also address certain chemical threats (different cartridges go after different chemicals.)

I actually find a respirator a bit more comfortable to wear than a N95, I'm more confident of the face seal and they filter out even smaller particles. (Not actually relevant for me--I have it for dealing with crab grass. My allergy isn't enough to be dangerous but it does mess me up.)

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Except for the smell of acetic acid, an ingredient in both the fixer and the stop bath, photo chemicals are relativity benign. Some rare cases of contact dermatitis which goes away if usage is stopped.

I personally have worked with and breathed them for more than 55 years. I am 83 and still kicking. Besides, I was a registered environmental assessor, and I say you have little to fear. That being said, you are better off mounting an exhaust fan to expel chemical fumes. Such an installation is tricky because is must not leak light.

You can cut a hole in the drywall (wall) and mount a small fan. You can use one designed to ventilate a bathroom. Drywall walls are usually hollow. You cut another hole, offset from the fan hole. This can be up, down, or sideways. The idea is, you create an exit path for the fan output. The offset is a light trap. The offset must be 1 yard / meter from the fan. Spray flat black paint inside the wall.

If this is too much for you, you can buy an light proof darkroom ventilating fan.

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  • 4
    Alternatively use a ducted bathroom fan, and get hold of black ducting, putting an S-bend into it. If the darkroom is humid (quite possible if trays of water-based chemicals are left open) that's better than venting via the wall lining and potentially causing damp
    – Chris H
    Apr 23 at 8:22
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    @RayButterworth I’m assuming Alan Marcus was referring to interior walls. He should probably be more explicit.
    – Eric S
    Apr 23 at 15:06
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    I personally have worked with and breathed them for more than 55 years. I am 83 and still kicking. With that said, anecdotal evidence is not terribly useful. My grandfather is a similar age, smoked heavily all his life, drank heavily all his life, and on two occasions suffered such grievous injury that he was put into a body cast. Because he survived this abuse is not evidence that the same would be true for anyone else. Not that yours isn't a reasonable answer, but your singular survival is not particularly telling evidence to support that answer.
    – J...
    Apr 23 at 20:58
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    @AlanMarcus I presume that's a question for me, and if so that's not the point. I was pointing out only that the line of reasoning you were using was fallacious, not that the conclusion itself was wrong (and explained as much above). A scientifically credible set of evidence to use would be one that included statistical analysis of a study group, with controls, that was able to demonstrate that the risk level was unchanged.
    – J...
    Apr 24 at 10:12
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    @AlanMarcus Consider, for example, the situation where one in a million people develop some disease in the general population, but one in ten thousand darkroom users do, that's still 9999/10000 people who come out fine, even though the activity in question increased the level of risk by a factor of 100. Anecdotal evidence of a single positive outcome is insufficient to reveal this increase in risk.
    – J...
    Apr 24 at 10:13
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In general, don't.

It's far better to ventilate the darkroom than to wear a respirator. Easier on you (respirators are stressful to wear, as everyone ought to know after more than a year of COVID-19), and more effective (you don't have to think about having a second set of exhaust fans if you invite someone in to watch you work in your darkroom or instruct you in a particular technique).

There are few chemicals used in modern photography that would make a respirator preferred over a good exhaust system, and some (those with an ammonia scent, for instance, or which exude sulfur compounds) make exhaust a better protection than a respirator.

If you can't add ventilation, then mix your chemicals outdoors, with the breeze at your back so the dust and fumes are blown away from you -- or prefer dustless and odor-free chemicals in your buying decisions.

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  • Use of a respirator does not preclude adequate ventilation. Your answer treats it as either-or, when it is quite obviously a yes-and. Apr 29 at 20:19
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It depends on one's particular needs.

Developer is quite toxic, fixer and stop - not really.

Developer doesn't evaporate anything except water vapor, stop and fixer evaporate some non-toxic (but smelly) ingredients.

Nothing in the process hints that one can get mist of doplets of any of the solutions and inhale them.

Dry forms of the chemicals can create some dust. Not really an issue, but can be irritating.

Now, what do you want to prevent?

  • Touching your face with dirty hands? Wear a covid mask (and probably safety goggles).
  • Inhaling the dust from the dry chemicals? Wear a covid mask (and probably safety goggles).
  • The acidic smell? Wear a covid mask and a cotton mask soaked in sodium bicarbonate solution over the covid mask (and probably safety goggles as well).

There are respirators w/ changeable filters that can help you with the last point.

The first point is really important only if you want kids in the darkroom with you. If this is the case, also bear in mind that some developers smell sweet and are still poisonous.

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    You can avoid getting chemicals on your face from touching with dirty hands simply by keeping your hands from getting dirty. When I did dark room work, I had several sets of tongs to move prints between the chemical baths, and never touched the paper or any of the chemicals with my hands. Most places that sell photo supplies will have these tongs for sale for dirt-cheap. Only time I used my hands was to remove the print from the final water bath, which should be relatively harmless (containing only trace amounts of fixer maybe). Apr 23 at 14:51
  • Not everyone can maintain a strict protocol. Children are notoriously bad at it.
    – fraxinus
    Apr 23 at 15:00
  • Oh, that's what you meant about the first point. Wasn't an issue for me as the last time I did dark room stuff was in college, using the school's photo lab. Children weren't generally around, so this wasn't something anyone needed to worry about. Still worth making a note about tongs though. If the past year is any indication, I imagine it also might be a challenge getting some kids to keep their masks and goggles on... Apr 23 at 15:07
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I agree with the answers that suggest that you don't need a respirator for health and safety reasons, but if you simply don't like the odor of acetic acid or if you are worried about exposure to the point of distraction, then follow the recommendations of the manufacturer as published in their MSDS (Material Safety Data Sheet).

As an example here is a PDF MSDS for Kodak Indicator Stop Bath. Note that there are separate recommendations for the concentrate and for the working solution.

The MSDS says to use ventilation first and foremost, and if this is not adequate, use a respirator with an organic vapor cartridge. This would be the same cartridge as you would use for paints and solvents.

You should be able to find an MSDS for any brand and type of darkroom chemical that you plan to use.

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  • I agree using a respirator is possible in a well ventilated space. Apr 29 at 20:21

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