"Safer" Wet Plate?

Discussion in 'Alternative Processes' started by haziz, Sep 30, 2008.

  1. haziz

    haziz Subscriber

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    I will be exploring wet plate photography next week in a workshop setting and have started to read about the process. I tend to be cautious with chemicals and would like to try to stay as safe as possible at least initially and probably long term. We will be doing both negative and positive images mainly using glass.

    1. Any input regarding use of only alcohol rather than alcohol/ether for the collodion?

    2. Using sodium thiosulphate or ammonium thiosulphate for fixing rather than potassium cyanide?

    3. Any reason that Ammonium thiosulphate or commercial rapid fixer (probably in "film strength") is not as popular as sodium thiosulphate as the fixing agent? Is it just tradition? I prefer neutral rather than warm images in general which makes me think sodium or ammonium thiosulphate may be the way to go.

    4. I do prefer a neutral image colour rather than warm images? Any suggestions?

    Thanks.

    Sincerely,

    Hany.
     
  2. rwyoung

    rwyoung Member

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    Re #2 and #3 with the KCN you get a nice "coffee and cream" color that you don't get with hypo.

    Re #1 you can browse a bit here and also spend some time over at www.collodion.com/forum

    Re #4, the hypo will produce a bit more neutral color.
     
  3. Barry S

    Barry S Member

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    Good luck--I tried registering there a month ago and my login still isn't activated.
     
  4. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    To me, the hypo- fixed images aren't just neutral, they're COLD - very hard silver colored, which is rather displeasing to my eye. I have been using the hypo as a fixer because it is "safer", but it gets costly as it must be used at a stronger than film strength dilution.
     
  5. Jim Noel

    Jim Noel Member

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    Those of us who want the original color but don't want to use cyanide use ammonium thiosulfate rather than hypo as a fixer.
    As for the use of ether, it is a volatile solvent as is alcohol. Many people use denatured alcohol in place of ether very successfully. It takes longer to evaporate, and thus dry, than ether, but it works. Some denatured alcohols work better than others. The one I use is denatured with ehtanol which works very well.
     
  6. Jim Noel

    Jim Noel Member

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    The site was down for upgrade for awhile and some problems persisted.Itis now up and running normally. Sean is very attentive to individual problems. Try again.
     
  7. smieglitz

    smieglitz Member

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    There are so many variables (cations, iodide:bromide ratio, age, alcohol type) with the formulas I've tried that it is difficult to say for sure, but I think the low ether/high ethanol mixes produce a much more fragile film that lifts from glass more easily. I can't really say whether the age of the collodion or whether different salt varieties I tried didn't impact the tenacity of the films more than the alcohol:ether ratio, but it seems to me some additional ether needs to be added to collodion USP to give the film adequate strength.

    You can't entirely avoid ether in the process since it is already present in the collodion. Ether in combination with strong alcohol is needed to dissolve the nitrated cotton. Either solvent by itself is not sufficient to do so.

    But, ether presents a storage problem since the fumes are explosive if concentrated and explosive peroxides will also form in it over time. Most institutional guidelines I've read recommend disposal of opened stocks of ether after 3-6 months. Don't store the ether inside a residence or near ignition sources, and though it is best to keep it cool, in the dark, and in a well-ventilated space, don't use a regular refrigerator to store it since sparks from the motor could set off any fumes that have accumulated inside the box.

    The best compromise is to purchase the smallest quantity of ether that you think you'll use in a period of a couple months and not have any excess that you'll have to store. Adding it to the collodion or alcohol will help stabilize it and minimize the rate at which peroxides will form, but the fume hazard still is present and proper storage conditions are necessary for safety. BHT is a chemical additive found in some ether stocks that also helps slow peroxide formation. And keeping oxygen out of the bottle will also help minimize the formation of peroxides. Adding marbles to displace the volume of solution in the storage bottle and/or using a nitrogen blanket at the ether-air interface will also help minimize peroxide formation. Be sure to read the MSDS before using any of these chemicals. You might also want to consult a chemist in regard to the safe handling and storage of all the chemicals used in this process.

    There is some anecdotal evidence that denatured alcohol in place of grain alcohol slows the aging of collodion or rejuvenates it, but of course the denatured stuff is toxic and thus more of a hazard than grain alcohol. Another thing to consider is the water content of the alcohol. Collodion must have some water to keep the film open to chemical action, but too much water causes problems. Alcohols with around 4-6% water content (e.g., 190 proof Everclear) seem to work best.

    Shorter development times generally promote warmth in the plate color though KCN fixer really warms it up. I prefer the warm color but I don't find the difference personally appealing enough to use that poison. I use ammonium thiosulfate instead and get quick fixing times without the added risk. Addition of some potassium nitrate or silver nitrate to the developer also is supposed to make the plate color more neutral and my casual observation supports that. Some workers add a few drops of solution from the silver sensitizing tank to the developer to get that effect. Reusing developer also promotes the neutral color since some silver comes off the plate during development and ends up in the developer solution.

    Sorry to be so long-winded, but the chemicals in the wetplate process should not be handled casually because they do present hazards. The hazards are manageable and getting the proper information is the first step in safely working the process.

    Joe
     
  8. Barry S

    Barry S Member

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    I tried again--got a page of error messages this time. No way to contact the admin--very frustrating.
     
  9. Quinn

    Quinn Subscriber

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    Hello Barry,
    My site is there - you can send me email through http://www.studioQ.com/contact (just for future reference)
    I found your account and activated it too. I'm usually pretty good about responding to email, don't hesitate to contact me if you have a problem (thanks Jim). Everything (fingers crossed) is back up and working on the collodion forum board now. I hit a rough spot recently, but it seems to be smoothing out now.

    Thanks.
     
  10. Barry S

    Barry S Member

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    Thanks Quinn, I appreciate it and look forward to joining the forum!

    Cheers-- Barry
     
  11. Jim Noel

    Jim Noel Member

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    Contact Quinn at wetplate@gmail.com

    I am sure he will respond. Don't forget that he is in Germany and may not r4spond until the next day in the U.S.
     
  12. Whiteymorange

    Whiteymorange Member

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    Just trying to understand, here. Denatured alcohol is ethanol, with another substance added to make it undrinkable. The traditional additive is methanol ("methylated spirits" is another name for this.) Ethanol can be "de-natured" with other substances, but not, I think, with itself.
     
  13. haziz

    haziz Subscriber

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    Any way of replacing the cadmium with another cation and keep the formula cadmium and extra ether free.

    Full formula please.

    Thanks.

    Sincerely,

    Hany.
     
  14. Jim Noel

    Jim Noel Member

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    There apparently are several different alcohols denoted as "denatured".
    What I have, as stated on the label, is methanol, "denatured with 10% ethanol".
    As I understand it to "denature" is to contaminate an alcohol with some other substance.
    If I recall correctly, in the past methanol was denatured with something to make it taste horrible so that people would not drink it. Methanol, as you know, is poisonous.
     
  15. smieglitz

    smieglitz Member

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    The various cations have little to no impact on the speed or contrast of the image. Rather, the iodine and bromine quantities and ratio are important. However, the cations do impart some properties to the collodion that may or may not be desirable. Generally:

    • cadmium salts thicken collodion and improve shelf life of salted collodion, however, cadmium is a toxic heavy metal; cadmium-salted collodions may be more fragile and also lift from the surface of the plates more readily and so may require an albumen subbing treatment to improve adhesion;
    • potassium bromide requires some additional water to dissolve and easily precipitates out of the collodion; It imparts a longer clearing time to freshly mixed stocks; It works so well that I suspect it somehow balances the optimum water and dissolved salt content of the collodion; If any bromide (NH4Br, LiBr, NaBr, CdBr2, etc.,) is present in the mix along with potassium iodide, potassium bromide will form and precipitate from the mixture;
    • ammonium salts dissolve readily and are useful when quick-clearing formulas are desired for immediate use; however, these collodion formulas have a limited shelf life and the contrast characteristics will change more rapidly than when using other salts (which is not a problem if it is used up quickly); ammonium salts may generate fumes that some find irritating;
    • sodium salts are relatively inexpensive and can be used but they tend to promote rapid dessication of the collodion film and this may induce drying artifacts on plates;
    • lithium salts also work but I haven't had the opportunity to shoot with them yet. I just mixed a batch last week and plan to experiment later this week. I suspect the collodion will perform well although its shelf life may be limited;
    • zinc salts are found in some antiquated formulas but I don't know of anyone actively using them today.

    You can substitute one salt for another in the formulas but to get similar speed and contrast, the molecular weights should probably be considered when substituting salts. Practically, it won't matter much which ones are used as long as the iodide to bromide ratio is ideally about 4:3 for ambrotypes and 5:2 for negatives, and the iodide content is about 1.1% by weight. Bromides increases the spectral sensitivity into the green while iodides add speed and contrast up to a point. An all-iodide collodion is going to be faster and higher contrast than one with some bromide in it. As any collodion ages, the contrast generally increases and the speed decreases.

    As far as specific formulas, the one you've obtained on the collodion forum is probably as good as any. However, I would again caution that a low-ether collodion may be very fragile.


    Joe
     
  16. AgX

    AgX Member

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    Principle solvents for cellulose nitrate are:

    Ketones (Acetone)
    Esters
    Ethers (Glycolether)

    Further there are non-solvent-mixtures (containing components which own their own are not able to dissolve cellulose nitrate):

    Ether-Ethanol

    Ether-Ethanol-Butanol

    Ethanol-Toluol

    Ethanol-Benzene
     
  17. WarEaglemtn

    WarEaglemtn Member

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    First things first. Take the workshop and produce an image or three using whatever methods are taught. Then go home and use the methods taught until you can get good, reliable and repeatable results. Then change one thing and see if your results are still as good.

    Wet plate can be confusing as so many variables are involved. Learn and use what you learn to successfully make images before changing or exploring.

    If you don't and run into trouble you have no idea what went wrong and no real experience to help in troubleshooting what went wrong.