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View Full Version : New batch of paper emulsion -- it gets better!



tim_bessell
03-03-2010, 07:07 AM
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.

:p gonna use the rum as an internal body lotion :p

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. :confused: 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

Photo Engineer
03-03-2010, 08:07 AM
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

sperera
03-03-2010, 08:09 AM
yes, scan em and post em....people like you are inspirational....

tim_bessell
03-03-2010, 08:26 AM
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.

tim_bessell
03-03-2010, 08:38 AM
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

Photo Engineer
03-03-2010, 08:43 AM
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

tim_bessell
03-03-2010, 09:26 AM
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.


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.


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. :confused: 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

Kirk Keyes
03-03-2010, 10:29 AM
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.

Photo Engineer
03-03-2010, 10:31 AM
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

paul_c5x4
03-03-2010, 11:04 AM
Let's see; (5.5" * 22")/12 = 10.08 sq. ft. I use ~15.0 mL. :confused:

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

tim_bessell
03-03-2010, 11:15 AM
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

Absolutely Paul! I'm a woodworker; must have board ft on the brain.

1 board ft = 1" x 12" x 12". Gee, that's what you said, there's the 12*12! Must go to bed soon.

T

tim_bessell
03-03-2010, 11:26 AM
Tim;

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

I did not see this when I coated the batch that had rum added, only after I used 91% isopropyl alcohol from Walgreen's. Inactive ingredients ... water. Well, so the label says. And this is using the same lot of Arches paper.

Fabriano is the paper i have problems with.

Must look at my notes, must take better notes!

T

Photo Engineer
03-03-2010, 11:29 AM
IPA (iso-Propyl Alcohol) is not a hardener, but the other 9% might be something to be concerned about. Some denatured alcohols have some pretty strange ingredients in them.

PE

Kirk Keyes
03-03-2010, 12:18 PM
IPA (iso-Propyl Alcohol) is not a hardener, but the other 9% might be something to be concerned about. Some denatured alcohols have some pretty strange ingredients in them.

There's no need for a denaturant in isopropyl alcohol (isopropanol) as it's one of the additives used to denature ethanol. Sometimes isopropanol when sold as "rubbing alcohol" has perfume, oils, surfactants in it, but those typically contain 70% isopropanol. (Ethanol is sometimes sold as "rubbing alcohol" as well.)

I see the product listed on Walgreens web site as "Walgreens Apothecary Isopropyl Alcohol 91%" - it very likely only contains isopropanol and water.

tim_bessell
03-03-2010, 12:50 PM
Kirk,
I'm inclined to agree with you. ThanX for checking their website.

Here is a scan of two prints. The original, in 35mm was shot on Kodak TMY and printed on Ilford MGIV FB. The other is an enlarged negative using a reversal process on Arista APHS. The enlarged neg was being made for cyanotype, this negative is a reject, but looked dense enough to work with my paper emulsion. It's a first try, not tooooooooo bad. I think a quick dip in some bleach would liven it up.

Ilford is on the right, of course, and mine on the left.

T

Photo Engineer
03-03-2010, 01:56 PM
You guys are right. A bottle of Ethanol, labeled Denatured had the label "contains Iso Propyl Alcohol" and my mind did a glitch.

Just make sure that any denatured Ethanol does not cloud up when added to water. This indicates the possible presence of a denaturant that is incompatible with emulsion making and coating.

IPA has no hardening effects but it does act mildly, as I said above, as an antifoamant and a surfactant. Beware of those brands with oils and perfumes. They can cause coating problems.

Tim;

Your results are very fine. How do the exposures compare for time and lens opening?

PE

tim_bessell
03-07-2010, 06:10 AM
Tim;

How do the exposures compare for time and lens opening?

PE

Here is a test and a method that I have been using, not sure it will answer your question.

I have a Sekonic L-358 light meter that I remove the dome from, Sekonic calls it a Lumisphere. It will detect much lower light levels this way. I keep it set at iso 100 and use it as a standard to gauge changes in light intensity.

I made a contact print with a bare bulb, just like I have been doing. The exposure is 5.6 sec. I measured the light falling on the printing frame at Ev 9.5. I then set up an enlarger to make a 4x5 print and at f11 obtained a reading of Ev 7.5. That;s a two stop difference, so 11 sec. @ f/11 should be an equivalent exposure. I made several test prints like this on a condenser and a color enlarger. The print from the condenser enlarger had more contrast than the color enlarger print.

Two scans: top, a contact print and bottom, from the condenser enlarger. I actually used 13 sec. @ f/11 for the enlarger produced print, but that's only a third of a stop.

T

Photo Engineer
03-07-2010, 08:47 AM
Well, therein lies a problem Tim. An exposure through an aperture cannot be directly compared to a bare bulb unless there is a known check. What you should do is test some Ilford paper side by side with your coatings and evaluate the speed and contrast by producing the same approximate step wedge. This should help evaluate the relative tone of the silver image as well. Then we will know what the speed is compared to "normal" photo papers.

PE

tim_bessell
03-07-2010, 09:29 AM
Yes, exactly! That will be the next step (wedge, hee, hee).

I'm sort of at an impasse now. I want to be able to make a batch, coat a full sheet of 22 x 30 paper and put it away to dry, then trim to final size. How's that for putting the horse before the cart. It would be so much more time efficient; something I never have enough of.

I still have a long way to go, perfecting the whole process from making to coating to holding a finished print in my hand. It will be an adventure, that's for sure.

T