Mercuric Iodide Red

[Allen in Montreal]

Gentlemen, I am in need of some memory jogging.

While rummaging around looking for some Chromium Intensifier, I stumbled across three bottles of Mercuric Iodide, Red. For the life of me I fail to recall when I have this stuff. Seems to me it was to change the color cast of some papers (ie to remove the green) but I am grasping at straws truth be told.

Anyone recall this stuff, why, when and how to use it?

Thank you,

[Merg Ross]

Used as a platinum toner or intensifier.

[CG]

Used in intensifiers, maybe other things. Toxic. Be very careful with this stuff. Best to use less toxic materials and find some college chem class teacher that needs some.

C

[Eric James]

What C said: it's nasty stuff. Here's the MSDS:


http://www.jtbaker.com/msds/englishhtml/m1495.htm

[Allen in Montreal]

Do you guys know the formula to use this as an intensifier by any chance?
I have a really nice 8x10 neg of my daughter that I shot as a test, on 15 yr old film that could use a boost.

Also, if this stuff is of any use to you Merg, or any of the platinum printers here, let me know, I can't see how I could consume three bottles of the stuff and I do not foresee an entry into platinum printing. At one time it was a desire, and I had a contact printer that sat unused for ages, realizing I need 90 hours in a day and 12 days in a week to accomplish all that I wish too, I gave the printer away.

[Merg Ross]

Allen, thanks but I will pass on the kind offer.

I did find a formula from my trusty Samuel Wein book of 1920 for intensification:

Mercury Iodide 15 grains
Sodium Sulphite 300 grains
Water 3.5 ounces

I would not, however, suggest experimenting on such a valuable negative.

Of course, heed all safety warnings.

I think if you do a Google search on the subject you will find detailed information from some of the older publishings.

[Don Dudenbostel]

Never used Mercury Iodide but used mercuric chloride in the 60's. It is a toxic substance for sure but just use caution when using it and keep it off your skon and away from food. I might suggest sing selenium toner to intensify your negs. It' very good and easy to use.

[CG]

There are safer intensifiers. I usually chide people who make a big deal about darkroom safety - but the mercuric chloride / mercuric iodide twins seem more nasty than needed.

Here are a couple of items far safer:

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Kodak IN-5

Stock solution 1
Silver nitrate, crystals 60gr
Distilled water to 1.0 liter

Stock solution 2
Sodium sulfite, anhydrous 60gr
water to 1.0 liter

Stock solution 3
Sodium thiosulfate, pentahydrated 105gr
water to 1.0 liter

Stock solution 4
Sodium sulfite, anhydrous 15gr
Metol 25gr
water to 3 liters

Slowly add 1 part of solution 2 to 1 part of solution 1, stir thouroughly.
A white precipitate will appear.
This is then dissolved by adding 1 part of solution 3.
Allow the resulting solution to stand for a few minutes until it clears.
Then add, stirring constantly, 3 parts of solution 4.
When the solution is ready, treat the film immediately, the solution is stable for approx. 30' at 20°C.
Degree of intensification depends on time of treatment which should not exceed 25'.
When degree of intensification is sufficient, immerse the film, with agitation, for 2' in a 30% solution of sodium thiosulfate.
Wash thoroughly.

-----
Kodak IN-4 Chromium Intensifier

Stock
Water 750mL
Potassium bichromate 90g
Hydrochloric acid, C.P. 62.5mL
Water to 1L

For use make working solution from 1 part bleach and 10 parts water.

The following steps can be carried out under artificial light or subdued daylight.

Make sure the negative has been well washed first. If using a dry negative soak in water 10 minutes. Treat only one
negative at a time.

Immerse negative in working solution, which is a bleach bath, for 8 to 10 minutes with agitation at (70° F). Discard
solution.

Rinse negative in running water or tray with continuous agitation for 5 minutes


Carry out the redevelopment in room light but avoid direct daylight.

Redevelop in a low sulfite developer like D-72 (Dektol) diluted 1:3 for about 8 to 10 minutes. Do not use developers containing a high concentration of sulfite such as D-76, Microdol X, or other fine grain developers.

Wash thoroughly after redeveloping.
Fix for 3-4 minutes.
Wash in running water for 10 minutes.
The process can be repeated for greater intensification.
Hang to dry.


Instructions condensed from: www.freelists.org/post/pure-silver/Mercury-Intensifier-VMI-was-Increasing-Grain,3
and: http://www.digitaltruth.com/products/formulary_tech/05-0065.pdf

Formula from: www.apug.org/forums/forum230/52024-kodak-4-chromium-intensifier.html

----
KODAK In-6 Quinone-Thiosulfate Intensifier

Solution A
Water 96 fl oz 750 mL
Sulfuric acid (concentrated) 4 fl oz 30.0 mL
KODAK Potassium Dichromate (anhydrous) 3 ounces 22.5 grams
Water to 1 gallon 1.0 litre

Solution B
Water 96 fl oz 750 mL
KODAK Sodium Bisulfite (anhydrous) 1/2 ounce 3.8 grams
KODAK Hydroquinone 2 ounces 15 grams
KODAK PHOTO-FLO 200 undiluted 1/2 fl oz 3.8 mL
Water to 1 gallon 1.0 litre

Solution C
Water 96 fl oz 750 mL
Sodium Thiosulfate penathydrate 3 ounces 22.5 grams
Water to 1 gallon 1.0 litre

To 1 part A, add - constantly stirring - 2 parts B,
Then, still stirring continually, add 2 parts C
Then, last add one more part A

Wash negs to be treated for 10 to 20 min.
Harden them in Kodak SH-1 Hardener.
And wash the negs again 5 min.

For maximum intensification, treat negs about 10 min at 68F.
Lesser time yeilds less intensification.
Agitate to prevent unevenness.
Only one neg at a time if in tray.

Wash 10 to 20 min and dry.
Stock solutions will keep several months in full stoppered bottles.
Mixed solution good only 2 or three hours.

Discard used solution after a single use - used solution will leave a silver scum on further negs.

Always add acid to water - not other way round.

Condensed from:Anchell's Darkroom cookbook

-----

C

[Don Dudenbostel]

silver nitrate, hydrochloric acid and sulfuric acid are extremely dangerous. All three cause severe burns to the skin, blindness if you get them in your eyes and ruin your clothing and potentially anything the come in contact with. When diluting acids the acid MUST be added to the water and NEVER add water to acid. High levels of heat are released when water is added to the acid and it can boil up into your face. I majored in organic chemistry in college and IMO the mercury compounds are much less dangerous if reasonable care is taken. Each must be handled with care.

[D. Bryant]

Never used Mercury Iodide but used mercuric chloride in the W's. It is a toxic substance for sure but just use caution when using it and keep it off your skin and away from food. I might suggest sing selenium toner to intensify your negs. It' very good and easy to use.
Mercury Chloride is the most toxic of the mercury salts and should be avoided. It has been documented as the cause of death of more than one chemical researcher over the years, people that should and did take more than reasonable precautions using it in their work.

In the hands of an amateur darkroom chemist it has great potential of health risks for them and their surrounding community.

Using this compound as a photographic toner implies that some of it will be flushed down the drain or disposed off improperly which is illegal in most if not all jurisdictions in the US and Europe.

I think it irresponsible to suggest one should, "just use caution when using it and keep it off your skin and away from food", since most if not all darkroom workers are not trained or do not have the facilities to handle this substance correctly and safely.

Only minute quantities of this compound need be ingested to cause permanent kidney, liver, or lung damage.

I know your intent was not to suggest someone place their health at risk but the stuff is really that dangerous.

Handling pure liquid mercury is comparatively harmless; handling any of the mercury salts are not regardless of the precautions one takes unless they are trained and equipped to do so.


Don Bryant

[Allen in Montreal]

There are safer intensifiers........

C

CG,

That is very kind of you, thank you very much!
I will explore these. Many moons ago, packs of Chromium intensifier laid around the darkroom like flies in a barn, it amazes me how much I have forgot in a few short short years "grace a" DigiCams!

[Allen in Montreal]

Mercury Chloride is the most toxic of the mercury salts and should be avoided.........In the hands of an amateur darkroom chemist it has great potential of health risks for them and their surrounding community.

Using this compound as a photographic toner implies that some of it will be flushed down the drain or disposed off improperly which is illegal in most if not all jurisdictions in the US and Europe..........

Only minute quantities of this compound need be ingested to cause permanent kidney, liver, or lung damage.....I know your intent was not to suggest someone place their health at risk but the stuff is really that dangerous.......handling any of the mercury salts are not regardless of the precautions one takes unless they are trained and equipped to do so.


Don Bryant

Don you raise a very good point.
It never occurred to me to consider the "legal" status of any such use. This bottles have been kicking around in my darkroom for 15-18 years or more.
I do use a dilution box as prescribed by city rules for darkroom use, but I also wonder what we subjected the darkroom techs to during all those years of "anything goes" film use. :(

[Don Dudenbostel]

As an experienced person trained as a chemist I would not suggest anyone inexperienced or untrained in handling strong corosives handle these chemicals. S there have been documented death from mercury compounds there have been many more cases of loss of eye sight and serius burns to the face and other parts of the body. Sulfuric, hydrocloric and nitric acids are the most corosives of acids. As you may know silver nitrate is basically silver disolved in concentrated nitric acid. I do not see the use of these acids as a safe alternative. Mercuric chloride intensifier was sold as a standard darkroom agent until sometime in the seventies. No question its toxic but I don't see it as a more dangerous material than these concentrated acids.

[CG]

Don, Looking at the formulas I mentioned - I'd swap in less concentrated acids so I didn't have to work with the worst stuff.

C