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  1. #151

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    Hi PE and Kirk,
    Thanks for the info.
    PE-It is interesting that soaking the coated plate in the dye solution works best here. I recall that you do not like this method for other dyes. Any idea as to concentration?
    Kirk-You are correct in that Everclear is not sold in CA. But I have just ordered some ethanol and already have methanol. I have to go through 3rd parties to get the latter. Ethanol is availible from The Science Shop. Also I can purchase 70% ethanol from any drugstore. But it is purposely mixed with some poison to keep people from drinking it.
    Cheers,
    Bill
    Agai, I have to wait for more silver befor I try this.

  2. #152
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    Bill;

    Do NOT use denatured alcohol. The added chemistry forms a colloidal suspension when mixed with water (among other nasty things) and will harm the emulsion.

    As for soaking the plate, this was done in early days to sensitize, but was time consuming and not very precise. The amount to use is quite debatable, and my friends could not even begin to suggest a starting point. The soaking would have to be by trial and error and then, how would you quantify it? This is an added difficult step, verifying the effectiveness of the sensitization step.

    PE

  3. #153

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    All sorts of chemicals are added to ethanol to denature it. You can see in the Code of Federal Register all the approved formulas for doing that: http://www.access.gpo.gov/nara/cfr/w...7cfr21_08.html
    From methanol to gasoline to pyridine are used - and you generally can't tell what you have when you get denatured alcohol. If the label says "SD alcohol XX" where XX is a number, you can look up in the CFR link above to find out which additives were used.

    On the chlorophyll, it sounds like they use the soaking method for sensitizing to minimze the degradation of the chlorophyll.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  4. #154

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    PE and Kirk,
    I will NOT use denatured alcohol. That is why I paid $13 for 1 pint of ethanol from The Science Shop. The 70% ehanol is sold as "rubing alcohol". So the added chemical is probably something of low toxicity, like IPA.
    I will just wait untill the ethanol arrives, then try to find ivy in the desserts of southern CA. Maybe spinach is not a bad idea Kirk.

  5. #155

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    Isopropyl is one of the denaturant used.

    A bottle of chlorophyll powder I've seen said it was extracted from spinach. Here's a nice extraction method that should clean up your extract pretty well.
    http://facstaff.bloomu.edu/mpugh/Experiment2.pdf
    It uses acetone for the extraction, and then cleans extracts the extract by adding water and hexane. The water will mix with the acetone hold onto the acetone and other junk in the first extract, and the hexane will extract the chlorophyll from the water/acetone mix. You can then blow down/evaporate the hexane to get rid of it and make some powdered chlorophyll to use in whatever solvent you want.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  6. #156

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    Kirk,
    Cool. I will buy some hexane.
    PE
    The ethyl alcohol I bought turned out to be 90% ethanol,5%methanol and 5% IPA. That annoyed me because it was advertised a "Reagent Ethanol". Probably OK for extracting chlorophyll. But I will try the procedure that Kirk suggested.
    But I can do nil until my silver arrives.
    Cheers,
    Bill

  7. #157

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    Bill - that mix for your ethanol should work pretty well for extraction. You could use it that way in the alcohol solution as a stock, or concentrate into hexane and then dry it.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  8. #158
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    Bill;

    That particular mix of denaturants is acceptable. At least as long as it does not turn cloudy when mixed with water. That is the crucial point with some denaturants.

    As for doing a pan emulsion, everyone I associate with here says don't until you have a good ortho emulsion and don't until you have good test methods set up to prove the sensitivity.

    PE

  9. #159
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    Ok, here is an update on chlorophyll supplied courtesy of Mark Osterman.

    In the Photographic News, 22 June, 1888, an early report is given that plates can be sensitized by chlorophyll. This work was by Ives and also by Abney. No methods are described, nor are results, merely that it has been achieved and was done by bathing the plates in alcoholic chlorophyll.

    In the textbook "Collodion Emulsion" by H. O. Klein, he describes the same work with much more detail including wedge spectrograms. He calls chlorophyll remarkably unreliable but good when it works. One problem is that due to the spectrum of chlorophyll, it can cause up to 5 peaks of sensitivity in the emulsion, and can actually increase blue speed. In fact, the increase in blue speed must be taken into account in order that one fully recognize that any red speed has been achieved.

    The stability of chlorophyll solutions is not commented on, but the implication is that it varies depending on source and on keeping conditions. One report says that the solution was stored over zinc powder to improve stability.

    All refer to it being best used by bathing dry plates in a solution of chlorophyll and then redrying the plates before use. They also comment that the sensitized plates keep better than unsensitized plates. No data is given on that.

    PE

  10. #160

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    Thanks P.E.,
    I am not trusting my life to chlorophyll as a red sensitizer, but I do want to try it. I also need to RE-TRY SDA-3057. This time at your recommended higher concentration and temperature. I have not been able to try anything this past week because I have been low in AgNO3 and low on time. But I expect to give them both a try this week.
    I am storing both the SDA 3057 and the SDE 8006 at 1% in methanol, in brown glass at a temperature close to 0 degrees C. The SDE 3008 comes partly out of solution , even when brought to room temperature. But warming to about 100 degrees F redisolves it.
    Has that been your experience?
    Bill



 

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