Thiourea based sepia toner question

[brian steinberger]

I learn something new every day on APUG... . So happy to have access to all this photographic knowledge.

 

[Buggs]

Tim Rudman's "The Toning Book" page 22:

snip...
"Firstly, they don't smell, so they won't fog your films and papers and your family will still love you."
...snip

In my mind this statement is suspect. You can't smell carbon monoxide (CO), but we all know it is very toxic.

 

[RalphLambrecht]

+1

 

[VaryaV]

Thank you for starting this thread, Buggs. I have similar questions to ask regarding paper fogging. I just started using Sulfide toners 2 months ago. Even though all my papers are in safeboxes inside the black poly they would still be prone to fogging vapors. Correct?

How do you guys set up your workflow outside then (to those who tone outside), because Rudman also states to tone under low light. If you are toning outside and away from your paper safe boxes are you in a tent-like structure (low light) or what are the conditions you are toning? Curious because that is the only way I could do it without fogging my papers. Right now my work flow is set up to do everything at once. Thanks.

 

[Buggs]

Varya,

There is a difference between fog caused by light and chemical fogging. I guess fogging is also caused by some types of radiation, but we are not talking about that here, fortunately!

When you bleach a print in preparation for toning, the metallic silver is converted back into a halide of silver, correct? Just how light sensitive is it? You would need to test your individual conditions to answer that question. I would venture to guess that direct sunlight may cause some unintentional damage or reversal of tones in the image. Subdued daylight would probably cause no harm, but test, test, test.

Remember, all the non-image forming silver has already been removed in the fixer. The toner just converts it into a more stable form of silver. The toning should be carried on to completion of all the silver that was converted.

Chemical fogging has been debated here, so whatever you can get away with on the point I guess.

The more informed ppl here will chime in with any correction to what I have said above.

tim

 

[pentaxuser]

T I have similar questions to ask regarding paper fogging. I just started using Sulfide toners 2 months ago. Even though all my papers are in safeboxes inside the black poly they would still be prone to fogging vapors. Correct?

/QUOTE]

That's the nub of the issue. Under what circumstances could this occur. In a totally enclosed darkroom, in a darkroom with the door or windows open, in a darkroom with the doors or windows open and a fan blowing the vapours out of the door?

Secondly and separately assuming you can personally stand the smell as a smell per se, at what point and under what circumstances does it become dangerous. Is it enough to open windows, use a fan as well or is it never safe except in the outdoors and with trays being downwind of you at all times?

It seems the PE has answered question on the circumstances for thiourea fogging but sulphide still seems unclear - well to me at least

pentaxuser

 

[Buggs]

If it wasn't such a fascinating hobby... i might run for the other side. No, no, i can't that's where i came from!

hahahahahahaHAHAHAHHHHAAAA...

 

[Gerald C Koch]

No level of hydrogen sulfide in your darkroom would be safe for your papers and films as the effects are cumulative. Toners that use sodium polysulfide like Kodak Brown Toner are more of a problem than those based on thiourea as they release more hydrogen sulfide.

The effects of low level exposure (approximately 4 ppm) in people is first eye irritation then headache and dizziness. This is followed by nausea, disorientation and confusion. The safe level for continuous exposure is 10 ppm. Because of osmic fatigue there is really no safe level for this gas as determined by smell. In the lab hydrogen sulfide is detected by using moistened lead acetate paper which darkens with exposure.

Most amateur darkrooms lack adequate or proper ventilation. They should have an exhaust fan that provides a relative negative air pressure. At one time Kodak published a book on darkroom design which listed recommended air exchange rates in cubic feet per minute.

 

[VaryaV]

Yes, indeed on all points. Let me rephrase my issue as I am not sure whether I was clear in my post. ….

In order for me to prevent chemical fogging while using sulphide (thiourea) toners in the d/r I would either have to move all of my paper safe boxes out of the d/r (which would be a total pia to do for just one process) OR move the trays outside and tone out there. And, moving outside I would have to build some ‘crude box-like structure’ in order to work under low light conditions. (which introduces yet another fogging problem.) I was wondering what kind of work flow others are doing to solve these issues. I haven’t seen any evidence of chemical fogging ‘yet’ but that doesn’t mean it’s not there. If Ron says it, I believe it so I figure need to make changes to my practice, just not sure which would be the most efficient/easy way. I have too much paper to risk ruining it and some of it isn’t made anymore.

Thanks again for your comments. Like you, I am really enjoying working and learning more about chemicals and chemistry. I grew up in a lab alongside my dad at the university, it’s only been recently I started to indulge in ‘that’ side of the spherical system.

Just saw your post Gerald. My d/r is its own structure built away from the house, however, it being in FL, it is very difficult to keep under climatic control, but I do it there because it's small and easier to manage. I have to keep EVERYTHING out there. I am assuming you chemists have separate storage areas and work in separate spaces then your main d/rs in order to prevent said issues? It is obvious from your post that I do not have enough ventilation which I will definitely be taking care of right away. Off now to read up on more and better types of ventilation and get a definition of what exactly 'adequate' ventilation means.

Thanks everyone. Good luck with your toning, Buggs.

 

[Gerald C Koch]

See if you can locate some darkroom plans online. They may give you some good designs. The most effective location for the exhaust is right above the trays on the wet side of the room. This way any noxious fumes are immediately drawn away from you to the outside. Also make sure that there is enough fresh air intake to compensate for the exhaust.

 

[Rudeofus]

In the lab hydrogen sulfide is detected by using moistened lead acetate paper which darkens with exposure.

Is there an amateur compatible test for H2S that does not involve Lead or other equally toxic materials? I'd hate to find and fine tune such an H2S detection method myself since I don't like winning a Darwin Award in the process.

 

[Gerald C Koch]

Is there an amateur compatible test for H2S that does not involve Lead or other equally toxic materials? I'd hate to find and fine tune such an H2S detection method myself since I don't like winning a Darwin Award in the process.

Not that I am aware within the cost restraints of the average amateur. Lead acetate test paper comes in small tubes and is of similar size to litmus paper. On exposure to hydrogen sulfide it turns brown or black. A tube should cost about 2 - 3 dollars. Amazon has them and also chemical supply houses.

 

[jim appleyard]

And just how nasty is lead acetate paper?

 

[pentaxuser]

The general guidelines seem to be 5 full changes of air per hour or 0.5cfm/sq.ft.

I wonder would wide open windows and a fan blowing the fumes towards the window achieve this change? As sulphide toning can be done in daylight then the answer to this might be useful for those without a built-in exhaust system but who favour the trad stinky toner as opposed to the thiourea one

Thanks

pentaxuser

 

[Gerald C Koch]

And just how nasty is lead acetate paper?

The amount of lead acetate in the paper is small. I really wouldn't worry about it.

 

[VaryaV]

Kodak still has some resources online:

Pub. AK-3: Darkroom design for beginners
Pub. J-98A: Safe handling of photographic chemicals
Pub. J-314: Indoor air quality and ventilation

The general guidelines seem to be 5 full changes of air per hour or 0.5cfm/sq.ft.

Good call. I built my d/r with instructions from an old Kodak book I picked up from our used book store. I will have to go back and check out the systems, there were several different types they showed.

I wonder would wide open windows and a fan blowing the fumes towards the window achieve this change? As sulphide toning can be done in daylight then the answer to this might be useful for those without a built-in exhaust system but who favour the trad stinky toner as opposed to the thiourea one

Thanks

pentaxuser

This is basically the setup I have currently but it isn't enough for me. I am extremely sensitive to chemicals. I had turpentine over-load while painting in my apt during college without proper ventilation. I can't handle noxious fumes of any sort, anymore so I need double the protection. I hate working fully masked and goggled. It's very uncomfortable but it's worth the results I am getting and it's fun. Over the holidays, David is going to install a bigger unit directly over the trays. Also, I am doing everything at once which I am going to stop and change my work flow. Print one day, tone the next.

Thanks for the tips.

 

[VaryaV]

Starting to see obvious signs of chemical fogging due to sulphide on the Foma MG 132 I was printing with yesterday. I am going to have to make changes to my work flow when toning. As my storage space for both papers and chemicals is limited to the d/r and (small) studio area I was wondering if I couldn't store the sulphide in my wooden microscope boxes. Would the wood or varnish react with it even since they're very old and well-seasoned? they're oak I believe and not cedar. (space is very limited out there)

I will have to carry toning out, in the other side of the studio from now on. It gets unbearably hot though in the summers.

Thought I should mention the paper fogging.

 

[Gerald C Koch]

I would assume that the wooden boxes are not air tight so they would be of slight help. Try using zip-lock bags for the boxes of paper. Square cookie tins work very well when the lids are sealed with black electrical tape. Some are large enough to accommodate 8x10 inch paper boxes. As I said before it's not a good idea to do toning in the darkroom either for paper or people.

 

[Rudeofus]

If you ever had to package smelly cheese for a longer trip, you will quickly learn that plastic bags, even multiple layers thereof, have zero stopping power over volatile compounds, however airtight they may appear at first glance. For this purpose people recommend a few layers of tin foil.

 

[Gerald C Koch]

Point taken. Not all zip lock bags may be the same as far as gas permeability. The freezer type are probably better. Certainly the tins are preferable for longer term storage.

I once was given a wedge of Port Salut cheese. It remained in the frig for a couple of weeks with the bag getting larger and larger. Evidently this stuff was making gas. When I finally opened the bag I had to evacuate the house.

 

[Buggs]

Some time ago I purchased a large coleman cooler to use as a water bath for E6 processing. All photosensitive materials are stored there. I carry out all my toning in a separate room, which actually has running water. I have had no problems with fogging... so far.

Varya, are you sure the source of fogging is caused by your toning chemicals? The reason I ask, I have some Ilford MGIV RC paper that is about 5 years old. I have used some recently and noticed many areas of black specks in the finished prints. These prints where processed BEFORE I had any thiourea in the house.

I have no idea of the source of the black specks other than age. A box of MGIV FB paper about the same age shows no such defect. Both have been stored in a dark cool basement darkroom.

T