Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,567   Posts: 1,573,483   Online: 744
      
Page 15 of 17 FirstFirst ... 591011121314151617 LastLast
Results 141 to 150 of 166
  1. #141
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,409
    Images
    65
    Bill;

    Chrome alum is the preferred hardener for gelatin on glass regardless of preparation according to two experts, one of whom coated glass plates commercially.

    Usually, you use either chrome alum or glyoxal at 10% in water, but remember that they both decompose over time. Also remember that glyoxal is nominally 40% in water so a 10% solution of that is actually 4%. I use the same liquid measure of either one, but they are both sensitive to other ingredients and I have had melts harden up instantly with both based on the pH and other ingredients present. And, due to the mix of ingredients and the expense, I was unable to identify the precise nature of the problem.

    Maybe someday I'll revisit the issue, but for now, I know that Chrome Alum or Glyoxal at equal liquid measure at nominal 10% dilution works. There is more precise information on this in your class notes.

    PE

  2. #142

    Join Date
    Apr 2005
    Location
    San Bernardino, CA
    Shooter
    8x10 Format
    Posts
    748
    [QUOTE= However, remember that Chlorophyll was the first red sensitizer. I have seen it done! It isn't good, but it works!

    PE[/QUOTE]
    Hello PE, I have been looking at chlorophyll, both suspended in water and extracted with methanol, with some success. I have been adding it as the final adition to the batches, and mixing at 45C for about 1/2 hour. Is there a better place to add the chlorophyll than at the end?
    Thanks,
    Bill

  3. #143
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,409
    Images
    65
    Bill;

    I have seen the sensitized emulsion, but have never worked with it. At our last lunch at GEH, Mark Osterman had about 100 ml of Chlorophyll sensitizer there to show us. Our next lunch is Tuesday. If I can go, I will ask him about it.

    PE

  4. #144

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Bill - did you buy some chlorophyll? Or did you extract it?

    It should be easy to grind up some spinach and then leach it with acetone and filter. A little magnesium carbonate can stabilize solutions, but chlorophyll degrades with exposure to light and I think it should be stored in the freezer.
    Kirk

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

  5. #145
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,409
    Images
    65
    Yes, I should have added that chlorophyll is not very stable once extracted and suffers if one overheats it during the sensitization process. It is reported to be very difficult to work with due to this stability problem.

    There are some plants that yield "better" chlorophyll than others. This should be available in the literature, but I'll check if I can.

    PE

  6. #146

    Join Date
    Apr 2005
    Location
    San Bernardino, CA
    Shooter
    8x10 Format
    Posts
    748
    Kirk and PE,
    Thanks for your support. Kirk,at first I mistook your advice about spinach as pure sarcasm. But now I realize it is a valid suggestion. Why acetone and not methanol? I have found reffrences to extraction via methanol.
    As to where I got my chlorophyll, I have used both an aquious suspension and a dry powder. Both were supplied as chlorophyll/copper compounds. In either case a methanol extraction, worked the best, as evidensed by shooting a color chart in daylight.
    PE- I am going to give the SDA3057 a second try once I receive my new shipment of silver,later this week. I want to keep both methods going.

  7. #147

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Bill - my info on chlorophyll is from doing the Standard Methods test for chlorophyll. They filter the algae, grind the filter with the algae in a tissue grinder using 90% acetone with 10% water saturated with MgCO3 as the extraction fluid. Then we centrifuge to get rid of the tissue and filter residue, and then analyse it for the chlorophyll content. So that's where my thoughts come from.
    Kirk

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

  8. #148
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,409
    Images
    65
    I would not use the form containing copper. It has potentials for side effects. Acetone may not be good either. The samples I saw, I was told, were extracted with Everclear.

    PE

  9. #149

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    What effects would acetone have? I seem to remember that Bill can't get Everclear in California, but I can in Oregon. At least according to wikipedia, he can't get 190 proof Everclear, but he can get 151 proof. Interesting, you can't buy 190 proof Everclear in New York state as well!
    Kirk

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

  10. #150
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,409
    Images
    65
    Well, at our lunch today, all agreed that acetone was not good as it can interact with gelatin and other emulsion ingredients.

    Use either ethanol or methanol for extraction, and some suggest common Ivy as a good source for fresh chlorophyll. I am told that coating the plate first and then bathing in alcohol+chlorophyll is best.

    I am supposed to get some references.

    PE



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin