[pure-silver] Re: Thiocarbamide Toner


----- Original Message ----- From: "Don Feinberg" <ducque@xxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, June 24, 2005 11:19 AM
Subject: [pure-silver] Re: Thiocarbamide Toner



There are a number of formulae in there Richard, including the old defender
formulae. At least some of the defender formulae worked very well a few
years ago.
Tim

I've used Ephram's formulae extensively as well as the Defender formulae. Both chemistries work well.


On a purely "what kind of results can you get" or "what is possible to achieve" basis, I prefer the Defender chemistry. However, there is a tradeoff: the thiocarbamide toners are admittedly somewhat toxic, but they are easy and safe to prepare and control. Sloppiness in preparation won't get you into trouble (well, as long as you're wearing rubber gloves, which I always do...).

Some of the Defender formulae, however, use HNO3 (nitric acid) as an ingredient -- nasty stuff. My issue is not that the preparation is all that difficult or unsafe, rather, that I really need to make damned sure I have my wits fully about me when preparing the chemistry. And I keep that concentrated HNO3 in a sealed nalgene bottle inside of another, larger, sealed nalgene bottle, in my locked steel chemical cabinet.

There is one other tradeoff which should be pointed out. In the last few years, something has changed in some of the papers I use. First, you should know that I heat-dry my prints using an Omega drum dryer. It used to be that the toned prints were totally unaffected by the drying process -- what you had after toning is what you had. However, I've found that some papers now lose practically all of the toned color in the drying.

I used to tone Ilford MG-IV "neutral", which, as is well known, doesn't accept selenium at all, this way. I was happily doing this for some time. But with the last couple of boxes of the Ilford paper, my process doesn't work. My process also doesn't work with Kodak Polymax Fine-Art, either. I have to air-dry both those papers if I want to retain the after-toning color.

On the other hand, if you tone the MG-IV with thiocarbamide to a really deep brown and then heat dry it, the result looks like what you think you would have had if the paper would have accepted selenium in the first place!

- Don Feinberg
ducque@xxxxxxxxxxxxxx
Thanks to you and Tim Rudman for confirming that the Defender formulas work with modern papers.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx


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