# New batch of paper emulsion -- it gets better!

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• 03-03-2010, 11:15 AM
tim_bessell
Quote:

Originally Posted by paul_c5x4
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
• 03-03-2010, 11:26 AM
tim_bessell
Quote:

Originally Posted by Photo Engineer
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
• 03-03-2010, 11:29 AM
Photo Engineer
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
• 03-03-2010, 12:18 PM
Kirk Keyes
Quote:

Originally Posted by Photo Engineer
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.
• 03-03-2010, 12:50 PM
tim_bessell
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
• 03-03-2010, 01:56 PM
Photo Engineer
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
• 03-07-2010, 06:10 AM
tim_bessell
Quote:

Originally Posted by Photo Engineer
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
• 03-07-2010, 08:47 AM
Photo Engineer
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
• 03-07-2010, 09:29 AM
tim_bessell
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
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