Mercury intensification

Discussion in 'Black and White' started by hernan_zenteno, Oct 8, 2013.

  1. Hello. I have a bottle of mercury intensifier that I preserved only for emergencies. The thing is that after 15 or more years I want to use it but I don't remember a few things. After put the negatives in the intensifier I need to take off the white layer that forms using a solution of some developer or a solution of sodium sulfite but I don't remember what kind of solution. And the other thing is the last negative I used with this type of intensifier is a bit fade. Can I wash and use selenium to make permanent the mercury intensifier or are there any incompatibility? I know that I have to use gloves and that mercury is poisonous. Many thanks in advance
     
  2. Seems that there are four choices ...
     
  3. Do you know which mercury intensifier you have? I have some instructions for VMI (Smith Victor) including some instructions for after treatment.
    Incidentally, I wouldn't recommend relying on gloves. I'm no expert, but some mercury chemicals are surprisingly poisonous. I know this isn't the mercury compound that you have, but this is worth reading:
    http://en.wikipedia.org/wiki/Karen_Wetterhahn
     
  4. Ah, I knew that there were a reason to use developer (dektol) or sodium sulfite. One is more strong that the other. Many thanks Glen.
    John, I finally did the intensification with sodium sulfite using gloves. All was ok, hope to not dead in six months. But for what I remember this solution is not so dangerous, obviously you can't drink it and must take it with extremely care. The kind of intensifier I used is from a local mark, Romek, but they don't do anymore this product and I can't find the instructions. I suppose that is very similar to Victor or old Kodak intensifiers. I will appreciate to know the instructions to compare with the other sent by Glen.
    The only thing I really don't have any clue is if I can do more archival the film processed with mercury intensifier applying a bath of selenium to avoid the fade thru the years. Anyone knows if this is viable? Or any other method to avoid the fading?
     
  5. I would guess a selenium bath should prevent the fade.
    I would also guess the chromium version would not fade, as you re-develop to completion.
     
  6. Hi Peter. I think so but what worry me is if some chemical reaction could be poisonous or play at the inverse staining the negatives or fading them more fast. I don't know if after mercury intensification I can use a simple selenium bath cause the emulsion must be composed by other chemicals after the intensification process. But I have no clue about chemistry at that level. By now I will scan the files I have interest and will do some back ups.
     
  7. Mercury Intensifier:
    Improves printing density of thin flat negatives.
    Water ----- 750ml
    Potassium Bromide 10 gr.
    Mercuric Chloride 10 gr.
    Mix at room temperate, add water to make 1 liter (1000ml)
    After mixing, use undiluted on negatives known to be thoroughly washed.
    Immerse negatives and agitate. Image will beach away. Wash bleached negatives in stagnant water bath containing a few drops of hydrochloric acid. Re-develop in a 5% solution of sodium sulfite. You may substitute a non-staining developer such as Kodak D-76 formula. If this developer solution is to be stored, keep in mind that a scum forms in the bottle. The scum will not affect the developers working properties but the fluid should be filtered before treating additional negatives.
     
  8. There is some info at this article by Steve Anchell. If the link doesn't work just google "anchell vmi" and it will come up. Sodium sulFIDE is used to make the image permanent.
    http://www2.rangefindermag.com/magazine/archives/index.taf?_function=getArticle&rowid=108&_UserReference=0478A48AA1571CDD4F3097EB
     
  9. Many thanks Alan and John. Appears that sulfide is what I need. Now I will have to ask where I can get that. Is not a common substance used in the darkroom. At less by me. Equal I will need to search the formula I used by Romek cause I saw that there are several differences between the mercury intensifier formulas. Maybe the permanence could be reached by the same chemical. Is nice to see that are a lot of people still in this kind of things. Here in Buenos Aires I am pretty like a dodo.
     
  10. Try a "brew you own" store. They use it to sterilise the bottles.
     
  11. Peter, I think you might be confusing two chemicals. The sulfide would be avoided in any food industry as it leads to rotten egg type smells. You might be thinking of metabisulfite, a common disinfectant for food equipment.
    I should add that the Steve Anchell article seriously glosses over the danger of mercuric chloride. He says it's caustic but doesn't stress the efforts that need to be made to avoid poisoning anyone or the environment. There are legal obligations.
     
  12. John, you're right. Nice catch!
    The mercury is the evil doer here. I was taught, many many moons ago in chemistry, that it is cumulative. We never really get rid of it. It's the multiple exposure that get's us in the end.
     
  13. Well. I used it and did an experiment. After the wash I put the negative in a weak selenium solution to see if the negative will be permanent, then I wash it again. At less until now the film show no stains but I will see in the future after some years. You can see the photo here. Many thanks for your help
    http://hernanzenteno.wordpress.com/2013/10/13/alchemy-in-the-bw-lab-en-espanol-al-final/
     
  14. I read somewhere years ago that regular 2-step (bleach & redevelop) brown toner works best. Mercury is nasty stuff. I wouldn't touch it, or breath it.
     
  15. Hi George. My experience is that not. Mercury is better for intensification but you are right that is a thing that I prefer to not deal. The main reason is that is dangerous and second cause have not a permanent effect. I only used it cause I have this old preparation and I wanted to get a good positive image. I found the old info paper that carried the box and they never mentioned that is something dangerous. I knew that from some years cause now this thing is forbidden in several countries. I am not sure that here too. I found too, late of course, some other old formulas by Kodak. But they have several chemicals that I doubt can find around here and one that appear best needed to be prepared in the moment cause only last 20 minutes and you need to work with safe light (silver intensifier Kodak In-5). Other, the In-6, needs sulphuric acid, that not sounds good either. Appears that all the intensifiers have some dangerous chemicals. The Kodak In-4 needs hydrochloric acid and potassium dichromate that accord some articles in the web was the chemical that made Erin Brockovich famous. The best thing is not fail during the exposure or during development. But several chemicals used in photography are not completely free of problems. The metol or Elon, for example, can cause problems on the skin for some people.
     

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