Chromium Intensifier

Discussion in 'B&W: Film, Paper, Chemistry' started by mrred, Oct 16, 2013.

  1. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    I found this recipe on the net.

    distilled water -- 75 ml
    potassium dichromate -- 9 gr
    hydrochloric acid -- 6.5 ml (more to reduce intensity)
    add cold water to make 100 ml

    I tried it and it works quite well. My question would be how long would this stuff last on the shelf?
     
  2. Gerald C Koch

    Gerald C Koch Member

    Messages:
    6,242
    Joined:
    Jul 12, 2010
    Location:
    Southern USA
    Shooter:
    Multi Format
    This formula is intended for one-time use. As such it has little reserve capacity and should not be saved. For safety reasons not something that should be kept on the shelf.
     
  3. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    What I stated is the stock formula. It is then mixed 1:10 for use, and that is one time use.
     
  4. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    Outside of it containing dichromate and hcl, does it create an additional combined hazard?
     
  5. MartinP

    MartinP Member

    Messages:
    1,458
    Joined:
    Jun 23, 2007
    Location:
    Netherlands
    Shooter:
    35mm
    What would be the advantages of this formula over the more standard selenium-toner, for negatives? (I'm assuming that you were using it on film, rather than paper).
     
  6. Ian Grant

    Ian Grant Subscriber

    Messages:
    18,034
    Joined:
    Aug 2, 2004
    Location:
    West Midland
    Shooter:
    Multi Format
    It's very much stronger in it's intensification.

    Ian
     
  7. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    +1 and you can repeat it. I also had everything to make it.
     
  8. Ian Grant

    Ian Grant Subscriber

    Messages:
    18,034
    Joined:
    Aug 2, 2004
    Location:
    West Midland
    Shooter:
    Multi Format
    In two parts the Chromium Intensifiers last decades. Ideally you need a Bichromate solution Part A and a weak HCl solution as Part B.

    Ian
     
  9. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    I guess the magic approach is to split them up and do 1:1:20. Thats workable. It's just not something you would use every day, hence my question.
     
  10. nworth

    nworth Subscriber

    Messages:
    2,191
    Joined:
    Aug 27, 2005
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    That formula is for a ready to use, one-shot intensifier. It works well. You bleach the negative in the solution and then redevelop in something like Dektol.

    Kodak IN-4 chromium intensifier
    Water 1 l
    Potassium dichromate 90 g
    Hydrochloric acid (conc) 64 ml
    Dilute 1:10 for use. Bleach negative thoroughly in the above solution. Wash 5 minutes, then redevelop in room light in a non-staining developer without excess sulfite. Degree of intensification may be controlled by degree of redevelopment. After redevelopment, rinse negative, fix, and wash. Repeat process for greater effect.
     
  11. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    And that would be a formula for 10 times more, and not answering the question (already answered anyway).... :smile:
     
  12. cliveh

    cliveh Subscriber

    Messages:
    4,708
    Joined:
    Oct 9, 2010
    Shooter:
    35mm RF
    Nasty stuff, take care.
     
  13. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    Driving a car will get me killed faster. Both are safe when operated safely and the car has a greater possibility of being an exception.
     
  14. richard ide

    richard ide Member

    Messages:
    1,227
    Joined:
    Nov 8, 2005
    Location:
    Wellington C
    Shooter:
    Multi Format
    AFAIK it is a hexavalent chromium compound. Look up the MSDS. Extremely toxic and recommended usage under a fume hood and no dumping down the drain.
     
  15. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    And I would repeat my last answer. I did say safely. Maybe now you can understand what I think of people with their ability to drive cars safely.
     
  16. Gerald C Koch

    Gerald C Koch Member

    Messages:
    6,242
    Joined:
    Jul 12, 2010
    Location:
    Southern USA
    Shooter:
    Multi Format
    After use the dichromate solution should be mixed with a sodium sulfite solution. This reduces any Cr (VI) which is very toxic to Cr III) which is less toxic before discarding. The yellow orange color of the dichromate will change to green.
     
  17. richard ide

    richard ide Member

    Messages:
    1,227
    Joined:
    Nov 8, 2005
    Location:
    Wellington C
    Shooter:
    Multi Format
    Thanks Gerald. Information appreciated.
     
  18. ArgentixCa

    ArgentixCa Advertiser Advertiser

    Messages:
    31
    Joined:
    Jun 9, 2013
    Location:
    Racine, QC,
    Shooter:
    35mm
    Hi mrred
    AFAIK, I would rather work with your product than drive in Montreal. For sure it will kill you faster to drive there.
    Each and every chemical products we use can be dangerous if used improperly.
    It is our responsibility to use it the way it is intended for.

    And yes, your recipe looks like the one I had in my old Encyclopedia of photography, Focal Press, printed in 1972.

    Best regards,
     
  19. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    I've been give lots of correct advice to be safe when using dichromate. I am not sure why it was assumed I didn't, but thanks all the same. It was good advice and reaffirmed what I was doing.

    It's no secret the contempt I have for bad drivers. Most show high degrees of being inattentive at the best of times. For the record, I don't drive and probably never will (and I am over 50 now). If I treated my chemistry like I see most other people drive, I would have been dead a long time ago.

    Please remember this when you are in your "lab" on on the "road".

    Oh, Montreal has the worst drivers I have ever seen. They seem take great pride with the disrespect they give others on the road. I'm glad they don't all have darkrooms.
     
  20. mrred

    mrred Subscriber

    Messages:
    1,120
    Joined:
    Mar 8, 2009
    Location:
    Montreal, Ca
    Shooter:
    Multi Format
    Rant over... :smile: