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  1. #61
    Mustafa Umut Sarac's Avatar
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    I am sorry , its 6 AM

  2. #62
    Mustafa Umut Sarac's Avatar
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    GRAINS

  3. #63
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    Mustafa, I have many projects. I really don't want to do this one and add to my burden. So sorry, but this is just too much for me to take on right now. I can give suggestions here, but that is about it.

    I have posted an SEM elsewere on this forum for one of my emulsions. It is a carbon replica SEM. It cost a LOT! I don't intend go further with this. I need to finish the book, the DVD and develop about 2 more or 3 more emulsions and then wind things up.

    Sorry.

    PE

  4. #64
    Mustafa Umut Sarac's Avatar
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    ok ron , sometimes have a look to this thread. I hope there are others who wish to help.
    I found this below :
    I think carbon copy is different from coating the sample with carbon.
    Well I will learn from China the cost.

    The resulting emulsion contained relatively polydisperse cubic grains with rounded corners. Out of 672 grains observed on a scanning electron microscope (SEM) at a magnification of 20,000 X, 21 grains (3%) showed a slight rectangular shape with a ratio of adjacent edge lengths of less than 1.3 and typically 1.1. SEM observations of grains tilted so that the thickness could be observed showed that the few grains present that appeared rectangular exhibited aspect ratios of less than 2. Emulsion B

  5. #65

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    Quote Originally Posted by Mustafa Umut Sarac View Post
    Making carbon replicas is a thing I never heard.
    Find a good book on SEM and read up.

    Actually, this thread reminds me of when I worked in a private analytical chemistry lab 20 years ago.

    Every time the phone rang at 12:15, it was some crackpot that was calling to have us figure out how to make some everyday item, which the crackpot could buy for usually less than $20, but the price had gone up $1 or so recently, and they wanted to make it themselves.

    Depending on the kind of item they wanted, I would explain that it would take several expensive tests to get just an idea of what the product they wanted to formulate was made from, and that would end up costing from $500 to $1000. And that was just to get us close to the answer. No guarantee that we would have a complete formulation at that point and that it could cost much more than that to get the more complete answer.

    Invariably, they would be shocked that it could even cost that much. They always thought we just poured the sample into some machine, pushed a button, and then we had the answer. I explained to them that they probably had been watching too much Star Trek - Next Generation and that there were actually no machines that could do analyses like that.

    So I'd ask them if they wanted to come one in and proceed with the testing and they would always say they would look around and call back. I would then offer the name of one of our competitors and suggest they try checking with them, thinking that the other lab would foolishly take the job and loose money on it because they would underbid the job.

    I actually had 3 people that took the offer up, and they were all businesses that needed to replace a product that was no longer being offered by their suppliers. One was a fire-retardant coating that was a mixture of superphosphate fertilizer and latex paint, another was a RV septic tank digesting solution, and the third was a water ski binder lube to get your feet into the bindings more easily. I did the work (which was much, much simpler than trying to figure out who made a photographic emulsion or how it was made) and all 3 times, brought the job in the range we had projected, and they were all happy that we could point them the direction to making a replacement product.

    Anyway, I just thought you all might enjoy my anecdotal story.
    Last edited by Kirk Keyes; 08-29-2008 at 02:05 AM. Click to view previous post history.

  6. #66

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    Quote Originally Posted by Kirk Keyes View Post
    Find a good book on SEM and read up.

    Actually, this thread reminds me of when I worked in a private analytical chemistry lab 20 years ago.
    Kirk,

    For some reason, your posts make you look much younger than that!

  7. #67

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    I hope no one thinks that I'm implying that Mustafa is a crackpot. It's just his enthusiam and unfamiliarity with the testing tools needed here reminded me of the story I related.

    Mustafa - I truly appreciate your desired to learn and tackle difficult subjects, and how you think up aspects that most people never would think about.

    Kirk

  8. #68

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    Quote Originally Posted by Ray Rogers View Post
    Kirk,

    For some reason, your posts make you look much younger than that!
    Thanks, Ray. I'll take that as a compliment. And most people usually underestimate my age (45). I'm starting to turn a bit grey, so I'm sure those numbers will be coming up shortly...

  9. #69
    AgX
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    More as a historical remark:
    In the fourties Land and his research team found that even the absence of nucleating agents could deliver a diffusion reversal image. In case the concentration of complexated silver was high enough the silver precipitated on its own in the receiving layer. Obviously this concentration issue hampers a use of such a system for continuous tone work. Or am I wrong?

    Carey Lea Silver
    I’m slow on the intake again:
    Why is everybody preoccupied with CLS as nucleating agent?
    In literature a lot of hints concerning heavy metals and other non-organic compounds are to be found. (Polaroid overcame the principal problem of controlling growth on their sulfide nuclei by “retarding” them in colloidal silica.)
    In another thread the issue of centrifugating is discuused. I assume this would be true of many nucleating systems.
    But is CLS really the most practicable way for a home lab?
    Last edited by AgX; 08-29-2008 at 10:39 AM. Click to view previous post history. Reason: spelling

  10. #70
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    Thanks for reminding me. Colloidal Silver Sulfide is another method used by Land to get nucleation on the reciever sheet, and colloid free sheets were used in some cases, but there was a nucleating agent of some sort IIRC. This goes way back for me, and our idea at EK was to do color mainly and to avoid any method used by Land. This was a concerted effort to avoid Land's patents.

    PE



 

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