selenium toning Ilford MG IV FB for archival purposes

[Ian Grant]

You don't see silver jewels fade, do you? (yes, I know this is a huge over simplification...)

Err, wrong they do, they tarnish, and get darker which people don't want. Rhodium plating is often used to prevent this happening

Selenium toning, (or sulphide) is like a controlled tarnishing, and this is what gives the increased archival permanebce.

Sulphide toning is not usually chosen as it has less desirable effects on image colour, in most cases people just don't want the colours it imparts.

Ian

 

[mcilroy]

Err, wrong they do, they tarnish, and get darker which people don't want. Rhodium plating is often used to prevent this happening

True, but as far as i know, this effect is comparable to what you get with sulfide toning

Silver is stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide, the latter forming a black layer of silver sulfide

source: Wikipedia

 

[Marco B]

You don't see silver jewels fade, do you? (yes, I know this is a huge over simplification...)

Err, wrong they do, they tarnish, and get darker which people don't want. Rhodium plating is often used to prevent this happening

Selenium toning, (or sulphide) is like a controlled tarnishing, and this is what gives the increased archival permanebce.

True, but as far as i know, this effect is comparable to what you get with sulfide toning

source: Wikipedia

X2, or should I say I see X3, as Ian already stated it himself that the "fading" is based on a sulphiding / tarnishing effect, which seems primarily caused by aerial pollution and not light. Ian, I was fully aware of silverware tarnishing , but this action is different from the effect of UV light.

Actually, we should maybe stop calling chemical attack in the form sulphiding/tarnishing the "fading of silver gelatine prints"... as it is highly confusing with the "other" fading of chromogenic colour prints caused mostly (but not necessarily exclusively) by UV light, and people from experience with paints mostly expect fading to be associated with exposure to light, and not so much chemical attack by oxidizing or reducing agents...

Just like we should maybe stop calling chromogenic colour prints "silver gelatine" prints, because there isn't any silver in them after full processing...

By the way, you are all going to love this story:

The Blue Man - Silver and Selenium:
http://www.jeolusa.com/APPLICATIONS/REALab/TheBlueMan/tabid/503/Default.aspx

 

[mcilroy]

X2, or should I say I see X3, as Ian already stated it himself that the "fading" is based on a sulphiding / tarnishing effect, which seems primarily caused by aerial pollution and not light.

Ah, right. Sorry Ian, i must have been reading a bit too fast

But that raises another question: If silverware gets a protective tarnishing on its own, wouldn't this be the case with silver in prints also?

 

[Ian Grant]

Ah, right. Sorry Ian, i must have been reading a bit too fast

But that raises another question: If silverware gets a protective tarnishing on its own, wouldn't this be the case with silver in prints also?

It is, that's the whole basis of archival toning with Selenium or Sulphide, creating a coating of a more stable salt around the silver grains.

Gold or another Precious metal works differently by replacing the outer shell with a metal that won't oxides at all under ant atmospheric conditions.

Ian

 

[mcilroy]

It is, that's the whole basis of archival toning with Selenium or Sulphide, creating a coating of a more stable salt around the silver grains.

What i was wondering is: If silverware gets this protective coating just by being exposed to normal ("dirty") air, shouldn't this be the case with untoned silver-prints also? Or does the silver sit in the emulsion too deep to react this way?

 

[Ian Grant]

It can happen in theory, and may happen in practice but the atmosphere contains to many pollutants that are more harmful.

It's rather like lens blooming, it was noticed by TTH that some Cooke lenses developed a natural coating, called blooming and that that helped cut reflections, but it was years before lens coating became common place.

Ian

 

[Marco B]

What i was wondering is: If silverware gets this protective coating just by being exposed to normal ("dirty") air, shouldn't this be the case with untoned silver-prints also? Or does the silver sit in the emulsion too deep to react this way?

Yes, it is happening. However, there is a fundamental difference that makes the sulphiding/tarnishing in silver prints caused by aerial pollution detrimental, versus a controlled sulphiding in a sepia toning being benificial to the print. Read the Gawain Weaver document I referenced before carefully to understand it:

The "difference" is that when a silver gelatine print is attacked due to aerial pollution, the formed silver ions (Ag+) have time to migrate in the gelatine layer of the paper before being "fixed" and deposited to form silver sulphide (Ag2S). This migration is possible because, although we may think the paper is dry, it actually contains enough water to facility both these reactions, and the migration of dissolved silver ions. I think I don't have to explain to you that any silver migrating from its original location in the print, can not be a good thing...

In addition, the deposited silver sulphide particles are far smaller than the original filamentous developed silver, and as a consequence of this, can be almost colourless or at least have a very light tone. As a consequence of that, the density of the print is significantly reduced, up to a point where hightlights and midtones may get virtually lost.

This is why it is called "silver gelatine fading"... as there is an irreversible loss in image density and detail.

All of this is not happening with a controlled sepia or selenium toning (or not to any appreciable amount), and the silver is converted to silver sulphide or silver selenide "in place", probably also due to the bromide in the sepia toner bleach which forms insoluble silver bromide as an intermediate step in the toning process, preventing the silver from going anywhere, and allowing the formation of relatively large toned silver particles again.

 

[mcilroy]

Thanks again!

I decided to "go the safe way" and ordered some MG IV Warmtone and Moersch's carbon toner (combined selenium and polysulfide). The MGW gives rather neutral tones in my developer but - according to Wolfgang Moersch - goes together very well with the carbon toner. Tone can be controlled to a rather great extent by adjusting dilution and time.

 

[brian steinberger]

For this paper I tone the highlights with a bleach sepia, to produce a warmth in the highlights, then gold tone which affects upper midtone low highlights to a slight peach , and selenium 1:5 one minute which attacks the shadows.

I love the look with MG4 and gives a wonderful split tone look.

Ilford warmtone, I prefer selenium 1:5 30 seconds with a very slight bleach sepia for highlights.

This sounds great! I will have to try myself! With MGWT do you sepia tone first as well?