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  1. #61

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    Quote Originally Posted by Photo Engineer View Post
    You may want to get a book on Steroids and Terpenes.
    Hmmmm. Terpenes. I love them. I have a box containing old terpene standards in my freezer. Every so often I get it out and smell the distinctive scent of each different terpene.

    The limonene would be nice if it works. You could extract the lemon zest for the limonene, and then use the lemon juice as a stop bath. 2 processing baths out of one fruit.

  2. #62

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    ah the kitchen was full of scents as I was tossing the thyme & sage into the cuisinart

  3. #63

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    Just did the Sage developer....works fine

    faint images after 40 min @ 80F with slight amber tint

  4. #64
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    Try Cabernet Sauvignon alone or with a touch of human urine.



    No kidding though.

    PE

  5. #65

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    well I did try to get some grape extract recently....but it was mixed in with other things I had already tested, so it wouldn't have been a good test for grapes


    it's a good thing I didn't know all this freshman year in college while I was (1) still a chemistry major and (2) attending a university with many Social Urine Sources ( known to themselves as fraternities )

  6. #66

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    A lot of articles describes effects with substances on AgHal in internet, but the effects could sometimes based on old articles, where they dont mentioned exactly on what kind of carier (collodium, simple paper, gelatine) these tests were done.

    Looking back exactly in the old standards of photochemistry literature like Hermann Wilhelm Vogel, the inventor of sensibilisation for photography, he dscribes a lot of substances. See "Handbuch der Photographie, I. Theil Photochemie und Beschreibung der photochemischen Chemikalien, Berlin 1890". He citates Carey Lea, who was testing on Collodium or simple paper (not our modern gelatine paper!!!) a lot of these substances with different results depending if paper or collodium, and Vogel mentioned, that in AgHal-gelatine these substances will have very little or no effect. A lot of articles later describes effects in internet are based on old articles, but they dont mentioned exactly on what kind of carier (collodium, simple paper, gelatine) these tests were done. All these substances, you read in this book, will have the old chemistry names, to retranslate in modern chemistry language you need a lot of time. An example from the glucosids: "Manna will give in carbonat alkali a strong and effectful picture ... pictures will have the most redish tones of all proved substances." There is a chapter with aetheric oils like (now german words) Nelkenoel, Camillenoel, Pfefferminz-(peppermint)oel, and there is a chapter with substances from plants, leafs, wood and so on ... Citation: "The following substances will have weak or no effects: Lakmus, Karthamin, Rutin, Colchicin, Nux vomica, Curcuma, Coffein, Berberin."

    For the experiment people: Salicylic-acid CAS 54-21-7 is a strong de-hardener for gelatine, you will get strong hardened films very soft in their gelatinestructure (once I tested), this could be interesting for old, too much hardened by time of storage aged bw-papers perhaps. Aspirin is a weak dehardener and available for everybody in your drugstore. And it helps against too much testing substances for yourself ...

  7. #67
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    Salicylic acid dissolved in alcohol, applied to skin will dissolve skin rather rapidly. It is used commercially in the US in a product called Compound W for removing warts.

    There are a number of chemicals that de-harden film or even better increase swell without removing hardening. It is difficult to tell which is which without sophisticated experiments. One way is that by increasing swell, you can still process in warm solutions, but you cannot if you unharden film.

    Also, you must remember that old hardeners such as chrome alum were easy to reverse, but formaldehyde was not. The newer hardeners are even less subject to dehardeners. In fact, dehardeners to some extent can be considererd compounds which decompose the gelatin.

    Takamine solution is an enzyme which totally dehardens and decomposes gelatin. It is very dangerous to work with as it can literally take the hide off of an elephant.

    Speaking of old chemical usage, Chlorophyll was one of the first chemicals used for sensitizing a silver halide emulsion to red (ish) light.

    PE

  8. #68

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    now that's interesting......I've always been curious about how the sensitizing dyes work

  9. #69
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    Sensitizing dyes are similar in structure to the dyes in the human eye. A group of C=C determines the color where 1 group is blue, 2 groups is green and 3 groups is red. This is a GROSS oversimplification.

    The difference between the eye sensitizers and film sensitizers is that one is designed to adsorb to organic (eye) sensors and the other (emulsion) is designed to adsorb to silver halide grains. (adsorb is loosely used for the eye as it is a different type of process than adsorption).

    The dye is placed in a solvent that can mix with water, and the dye is usually unable to dissolve in water, so when the dye (in solvent) is mixed with the emulsion, it heads directly for the grain surface where it can precipitate out and then transfer its energy to the emulsion.

    PE
    Last edited by Photo Engineer; 12-15-2007 at 01:31 PM. Click to view previous post history. Reason: spelling

  10. #70

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    thanks...very interesting



 

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