Thiocarbamide Tonergreenspun.com : LUSENET : B&W Photo - Printing & Finishing : One Thread
I am trying to find out about thiocarbamide toner. I recently purchased a book, "Creative Elements" by Eddie Ephraums. In this book there are examples and instructions on the use of many toners. I am impressed of the outcome in using thiocarbamide but can find very little about it anywhere else. Photographers' Formulary sells it under the name of "Thiourea." If anyone can share their knowledge about thiocarbamide I would appreciate it. I would also like to know about the toxicity and if special handling or precautions are required.
Thanks for your input.
-- Robert Bedwell (email@example.com), June 12, 2000
I too was intrigued when I saw Eddie's book. Over the past 1.5 years I have been planning to try some of his formulations, but I haven't done so yet. Let me know how you make out!
As far as Thiourea is concerned, it is a known or suspected carcinogen. Check out http://ehs.stanford.edu/servlet/chemsafe.lookup.class for info on specific chemicals. Good luck!
-- Pete Caluori (firstname.lastname@example.org), June 12, 2000.
Thiocarbamide, or, which is the same thing, thiourea is the basis for odourless brown toner. In contrast to the sodium suplhide toners which stink like rotten eggs, thiocarbamide toners can be controlled to some extent, i.e. the toning solution consists of an activator (I think that would be sodium hydroxide) and thiocarbamide, and the ratio of the two determines the image tone which can vary from yellow to brown.
Thiocarbamide is, as was correctly stated before, carcinogenic and should therefore be handled and disposed of with care.
-- Thomas Wollstein (email@example.com), June 13, 2000.
I've used the Fotospeed FT-20 odorless sepia toner, and I did not like the sickly yellow colour it produced.
-- Ed Buffaloe (firstname.lastname@example.org), June 14, 2000.
i've used the formulary thiourea with fantastic results. it's a bit of a pain to use. it arrives powdered, and you have to dissolve them into parts A and B. then for use you have to combine parts A and B. also, their bleach is WAY too strong for doing partial bleaching and then toning. it works way, way too fast. i used diluted kodak sepia bleach.
but, as i mentioned, the toning results were terrific. agfa viradon has produced similar results in tone, though i've had some problems with it scumming the paper. it also stinks. its great advantage is that it's a one-step toner.
-- brad daly (email@example.com), June 15, 2000.
The toner is very easy to use. Having said that, it also reacts to a wide variety of variables making repetition of a certain "look" somewhat difficult. The type of paper emulsion, type of developer, developer temperature, amount of exposure, amount of development time, and fixer type can completely change how the toner reacts.
Likewise, with the toner, the temperature, bleach concentration, bleach time, mixtures of part A and B, and time in the toner all have an outcome on the final color and effects. The only way to find out is to get the toner and start working. As the toner requires a bleach made from potassium ferricyanide (poisonous), and the toner is made from thiourea (carcinogenic) plus sodium hydroxide (extremely caustic) - I'd recommend wearing at least 4 mil rubber gloves (nitrile rubber seems to work best) for the whole process. I buy them in boxes of 100 and may use 2-3 during a toning session. The 4 mil gloves seem heavy enough to not tear but are thin enough to allow a fairly good tactile feel.
-- steve (firstname.lastname@example.org), June 15, 2000.
This is one of the best toners. I make from basic ingredients. And if you change the ratio of Thiorea to Sodium Hydroxide you get dark browns grading through to yellow brows. The chocolate browns are stunning with a fabulous tonal range. Tim Rudmans "Master Printing Course" has some recipes. AND they work beautifully with fibre AND Resin papers David Strachan
-- David Strachan (email@example.com), June 16, 2000.
I would like to thank each of your for responding to my question about thiocarbamide. You have been most generous with your knowledge and your time. I have gained much knowledge and I am continuing to the next step which is experimentation using your input.
-- Robert Bedwell (firstname.lastname@example.org), June 18, 2000.