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  1. #1

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    New batch of paper emulsion -- it gets better!

    Well, i'm really pumped now!

    Monday morning I made another batch of paper emulsion; same formula as previously made. This time I filtered the sea salt using a buchner funnel and filter flask. I should have mentioned in my other post that i cool my emulsion in a shallow pyrex baking dish as suggested by Mark Osterman.


    Tuesday morning i finished it with the digestion stage but added no more ingredients (alcohol, photo flo, and chrome alum in my formula) and chilled it once more in the fridge. I split the batch in half and added finals. I substituted isopropyl alcohol for rum.

    gonna use the rum as an internal body lotion

    My coating workflow is getting a little better. I modified my blade to hold enough emulsion to coat a strip 6 x 22 in., which is cut from a standard 22 x 30 sheet. That gives me fifteen 5 x 7's (in a perfect world) allowing for a little waste on the edges.

    All in all, the coating session went well. Until I decided to add rice starch for a matte finish. The starch made the emulsion so lumpy I couldn't even filter it. Need to work on that I guess. I managed one strip however with starch.

    This morning was trimming and testing time.

    Wow, wow, wow. I tested the matte version and it looks wonderful. Better contrast, brighter whites, and if it has Fairy Dust (hi Denise), my fairy is really a stingy little B---h.

    One interesting observation. As I processed several prints, I noticed the developer is almost completely repelled by the emulsion. In fact I had to hold it under with my fingers until the slight curl disappeared. The effect continued in the citric stop, and plain hypo fix to a lesser degree. I mean, i could see the emulsion was saturated with chems, but it came out of each bath like it was almost dry. After an hour wash in running tap, the water ran off pretty fast. I attribute this to the isopropyl alcohol. Hopefully PE will enlighten me on this, but I think is works great.

    When I get a chance I might scan some test prints.

    T

  2. #2
    Photo Engineer's Avatar
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    Tim;

    Congratulations.

    Here are some thoughts.

    Presoak the starch before adding it to the emulsion. That will help.

    The effect you describe is probably due to extreme hardness. IDK for sure, but mine do not behave that way. It could be the sizing in the paper itself which is somewhat of a hardener.

    PE

  3. #3

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    yes, scan em and post em....people like you are inspirational....

  4. #4

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    Quote Originally Posted by sperera View Post
    yes, scan em and post em....people like you are inspirational....
    Go for it! Believe me, it is tons of fun.

    Looking at some of my prints on manufactured paper, I see where I could make vast improvements in my technique, now that I know what I know.

  5. #5

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    Quote Originally Posted by Photo Engineer View Post
    Tim;

    Presoak the starch before adding it to the emulsion. That will help.

    The effect you describe is probably due to extreme hardness. ..snip... It could be the sizing in the paper itself which is somewhat of a hardener.

    PE
    I cooked the starch until it gelled, might be the problem there. I read one account of adding a small amount of gelatin to the mix before adding to the emulsion.

    I did some tests in white light on a spoiled batch of emulsion after adding iso alcohol and coating Fabriano. Then going through the dev., stop, ... ect., I observed the same thing. I thought it must have gotten pretty hard, but in the final water wash, the coating still came off the Fabriano paper.

    This session I only coated Arches paper.

    ... thanXXXXX PE for all your well wishes and thoughtful comments.
    T

  6. #6
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    Ok, don't cook the starch. Keep it as cool as possible. You want the starch to be incorporated as fine granules IIRC. That causes the matting effect to be best. All you need do is swell them.

    If the emulsion comes of in sheets or ribbons, or if it forms blisters it is hard with poor adhesion to the paper. If the emulsion dissolves, then the emulsion itself is not hard.

    The gelatin, as you coat it, should be no higher than 10% and should not go down at more than about 750 mg/square foot. If you get more or less, you have problems. The hardener, at 10% (chrome alum) should be 10 ml / 100 ml of this solution and should harden in about 1 day.

    PE

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    Quote Originally Posted by Photo Engineer View Post
    Ok, don't cook the starch. Keep it as cool as possible. You want the starch to be incorporated as fine granules IIRC. That causes the matting effect to be best. All you need do is swell them.
    Ok, i'll try that.

    Quote Originally Posted by Photo Engineer View Post
    If the emulsion comes of in sheets or ribbons, or if it forms blisters it is hard with poor adhesion to the paper. If the emulsion dissolves, then the emulsion itself is not hard.
    It forms blisters, almost like reticulation, starting at the edges and working in to the center. Some neat effects. I let one dry and it looked pretty wild. Now that I think of it, this is the exact problem i had with cyanotype and photo gelatin on fabriano.

    Quote Originally Posted by Photo Engineer View Post
    The gelatin, as you coat it, should be no higher than 10% and should not go down at more than about 750 mg/square foot. If you get more or less, you have problems. The hardener, at 10% (chrome alum) should be 10 ml / 100 ml of this solution and should harden in about 1 day.

    PE
    Let's see; (5.5" * 22")/12 = 10.08 sq. ft. I use ~15.0 mL. Can't think PE, i've been up since 21:30 yesterday, what's next. Assume 1 mL of warm emul weights a gram?

    I used 1 mL of 5% chrome alum per 100 mL emulsion. Hmmmm.... I was thinking of adding NO chrome alum and then try again doubling it. Still not enough according to you.

    What about the alcohol, it seems to me this has had an observable and real effect that looks like hardening.

    Sorry for all the questions.

    T

  8. #8

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    The alcohol should affect the viscosity and the surface tension of the wet emulsion and then some will evaporate as the paper dries and the rest of it will dissolve into the developer.

    I would not expect it to have an effect on hardness. It will help the wet emulsion flow more freely by reducing the viscosity and reduce some of the surface defects by reducing the surface tension.
    Kirk

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

  9. #9
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    Tim;

    With a 5 mil undercut, you use about 12 ml to coat 1 square foot and with 120 ml of 10% gelatin that is about 1000 mg / square foot. My statement above was too vague. The range for gelatin in this case would be from 500 - 1000 with an average of about 750. I coat between 5% and 10% so therefore the average is what I gave, not the exact value.

    As for alcohol, it should give no hardening effect whatsoever. You need alums or aldehydes as hardeners for home lab work. There are others, but they are generally too toxic for our use. Alcohol has a mild surfactant and anti foam property.

    I would guess that the clays in the paper are adding some hardening effect, but the paper is stripping away from the emulsion due to poor adhesion.

    PE

  10. #10
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    Quote Originally Posted by tim_bessell View Post
    Let's see; (5.5" * 22")/12 = 10.08 sq. ft. I use ~15.0 mL.
    I think your math is a little off - (5.5"*22")/(12*12) = 0.84 sq ft. or put another way - (5.5/12)*(22/12) = 0.84 sq ft.

    My math also falls apart after long days.. :o

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