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Kirk Keyes
12-08-2007, 11:21 PM
Denise Ross, a very talented photographer out here in Oregon is putting together a web site to share information and promote making silver gelatin emulsions. She plans to have the site ready for use right after New Years Day.

She made a post on APUG's sister-site, hybridphoto.com, today and stated that she:

"would love for the folks who are making emulsions to think about becoming a Contributing Editor to the Light Farm. Here's a heads-up to the page that talks about that: http://www.thelightfarm.com/howtopar...e/maptopic.htm

"Please note that it isn't linked to any other page right now. If you haven't been following the progress on launching this beast, here is the UnderConstruction page:
http://dwrphotos.com/blog/Section14/thelightfarm.htm "

I've been to Denise's studio and seen the silver emulsions that she makes and the beautiful prints from these emulsions. I'm sure her site will be quite interesting. I plan to participate and I hope others that are interested in making silver emulsions will come and check out her site and participate as well.

Here's some pages that Denise has on her personal web site on emulsion making - http://dwrphotos.com/blog/EmulsionResearch.htm that are really interesting. I'm sure her www.thelightfarm.com will be just as good.

Kirk

Kirk Keyes
02-02-2008, 03:03 PM
Denise Ross has just posted her website that is devoted to making photographic emulsions. She has examples and practical info on making papers, negs, gums, and more on the site.

It's called The Light Farm - check it out at http://www.thelightfarm.com/

Emulsion
02-02-2008, 06:19 PM
Denise Ross has just posted her website that is devoted to making photographic emulsions. She has examples and practical info on making papers, negs, gums, and more on the site.

It's called The Light Farm - check it out at http://www.thelightfarm.com/

Thanks Kirk,
The link is appreciated.

Denise has a very nice site with some excellent information for emulsion makers.

Emulsion.

gr82bart
04-14-2008, 12:44 AM
http://dwrphotos.com/blog/EmulsionResearch.htm

Interesting site.

Regards, Art

gr82bart
04-14-2008, 12:46 AM
http://www.thelightfarm.com/

Another emulsion making website. Prety neat too.

Regards, Art.

Ryuji
04-14-2008, 05:26 AM
It seems that the site you referred to only talk about enlarging emulsion, not negative-speed film emulsion...

Ryuji
04-14-2008, 05:39 AM
I don't know if the author of that site sees this thread, but here's my comment.

Pepper fog can be caused by poor choice of gelatin. Try different gelatins. Also, uniformity of mixing at the precipitation is the key. Pepper fog is a strange thing and one stock of gelatin I use never caused pepper fog, ever, while another stock of gelatin is very much more problematic.

Coating defects on papers can be caused by inadequate mixing when adding hardener, or can be caused by ineffective surfactant. The surfactant used in Photoflo (octylphenol ethoxylate) is not very effective for coating purpose, unless you coat slowly, or make multiple strokes (like when using brush). If you have no access to a better surfactant, try to wet the coating surface with plain dilute surfactant, immediately before coating the emulsion.

Guessing from the step tablet images, the contrast of the emulsion is very low... maybe that's how you wanted it...

David A. Goldfarb
04-14-2008, 07:56 AM
Yes, Denise posts often here and at hybridphoto.com

David A. Goldfarb
04-14-2008, 08:31 AM
Yes, this one is a newer updated site by Denise Ross, who put up the emulsion-making diary site that you mentioned in another new thread.

Three threads merged.

dwross
04-14-2008, 11:14 AM
Greetings Ryuji,

Because of the merged threads, I'm going to reply to your comments on the thread titled 'The Light Farm'.

Denise
http://www.thelightfarm.com/

David A. Goldfarb
04-14-2008, 11:30 AM
To reduce the amount of cross-thread confusion, I've merged the Light Farm thread (composed of three redundant threads already) with the Emulsion Diary thread, so that Denise can respond to all these points in one place.

dwross
04-14-2008, 11:50 AM
Ryuji,

In response to your comment from a previous thread:

"Coating defects on papers can be caused by inadequate mixing when adding hardener, or can be caused by ineffective surfactant. The surfactant used in Photoflo (octylphenol ethoxylate) is not very effective for coating purpose, unless you coat slowly, or make multiple strokes (like when using brush). If you have no access to a better surfactant, try to wet the coating surface with plain dilute surfactant, immediately before coating the emulsion."

You are probably referring to Photo-Flo 200, the form of surfactant most commonly used in the home darkroom as the final step in film developing. This is Ron Mowrey's preferred surfactant, but it didn't work for me. I use Photo-Flo 600 and Everclear exclusively as my surfactants (as of this day; I hope to try everything I've ever read in the old emulsion books at least once before the end of days).

I've never tried applying silver gelatin emulsion with a brush. There are a number of other ways.

(http://www.thelightfarm.com/Map/PaperAndCoating/MapTopic.htm)

But, thank you for the tip about coating the paper surface with diluted surfactant. It is the my hope and the goal of all the contributors to The Light Farm to be as complete a resource for silver gelatin emulsion making as possible. I'll give the method a try and post my impressions of how it works.

re: pepper fog: It's been my experience that pepper is primarily a problem of uneven silver addition during the precipitation step. I rarely see it anymore. But, I haven't strayed from the photographic gelatin sold by Photographers' Formulary, which seems to be of consistent high quality. I, and another TLF member, are going to be trying a number of gelatin options sometime around the first of June (give or take, it's not a front burner topic). I will be inviting other members (we are twenty so far) to
participate. The more information the better. Facts and personal experience are a great substitute for speculation :) .

It's great to see you weighing in again on this forum. I hope the conversations about silver gelatin emulsions can be rich and open and chunky with solid intel.

Denise

Photo Engineer
04-14-2008, 12:14 PM
Denise;

Photo flo 200 and 600 differ in that 200 is more dilute and uses propylene glycol as an additive while 600 contains ethylene glycol (at least this is what the MSDS and my bottles say). I use the former as it is less toxic, but they are basically the same except you use a different amounts of either as they differ in concentration. They are nonionic surfactants. The active surfactant in the Photo Flo series is what we used at Kodak for making our coatings. You can substitute Triton X 100, which is essentially the same thing.

As for pepper fog, I looked at the examples you posted of Azo. I was once told that Kodak had problems with baryta support on and off in the early years, and some Azo batches had pepper fog. If you have the right emulsion formula, there is none as you note. I have used about a dozen different gelatins and found it more dependant on the formula than gelatin. Kodak found that adding an ingredient to the undercoat or baryta for Azo paper solved their problem. The emulsion formula was ok.

I have made a batch of Azo type emulsion that showed pepper grain on one batch of Baryta paper, none on another and none on Strathmore, so I can believe that old story has some credibility. I believe that several people have seen some of my paper which Alex Hawley used for printing. I doubt if there is any pepper grain. Maybe they would care to comment.

PE

David A. Goldfarb
04-14-2008, 01:08 PM
I have made a batch of Azo type emulsion that showed pepper grain on one batch of Baryta paper, none on another and none on Strathmore, so I can believe that old story has some credibility. I believe that several people have seen some of my paper which Alex Hawley used for printing. I doubt if there is any pepper grain. Maybe they would care to comment.

PE

As it happens, I haven't shipped the Traveling Portfolio yet, so I have the print in hand at the moment, and looking with a 6x loupe, I don't see any pepper grain on Alex's print using your Azoish coating on Strathmore Smooth. I made a quick digisnap with my Coolpix 990 that mostly lives on a copystand for archiving documents, and at the camera's maximum magnification closest focus I couldn't see any either. I've attached a crop of the file showing an area about 20mm across from an 8x10" print. I've only adjusted levels and used a slight amount of Smart Sharpen in CS2 to match the print as best I can.

For scale, this would seem to be a full print from the same neg (but on Azo G3)--

http://www.apug.org/gallery/showphoto.php?photo=8093

Photo Engineer
04-14-2008, 01:28 PM
Thanks David for the independent opinion. I'm glad there was none there. I was pretty sure I had none at all in the Azoish emulsion, but it is good to hear that verified by others.

PE

dwross
04-14-2008, 04:54 PM
Photo flo 200 and 600 differ in that 200 is more dilute and uses propylene glycol as an additive while 600 contains ethylene glycol (at least this is what the MSDS and my bottles say). I use the former as it is less toxic, but they are basically the same except you use a different amounts of either as they differ in concentration. They are nonionic surfactants. The active surfactant in the Photo Flo series is what we used at Kodak for making our coatings. You can substitute Triton X 100, which is essentially the same thing.
PE
Ron:

In an email correspondence awhile back (12/27/06 if you are an email archiver), you mentioned a theory about the effects of the various Photo-flo additives to the basic surfactant (p-tert-octylphenoxy polyethoxyethyl alcohol). You were having problems with the 600 that I wasn't and you speculated that it was interacting unfavorably with the thymol in isopropyl alcohol you used as an emulsion preservative. I've never used thymol. I use up a batch of emulsion as soon as I get it cooked, and I'm not crazy about the Listerine smell, so I've never done a comparison test myself. I just know that PF 200 failed miserably for me, and when I switched to 600 and Everclear I left my surfactant problems behind.

Question: Do you still feel thymol in its alcohol carrier is at least part of the picture? If so, it is important to emphasize yet again that in emulsions, seemingly minor modifications can have a major effect. This, of course, I see as good news, not something to run from screaming. It means there is a lot of art involved and potential for customization. But, it does bear repeating that if a recipe or technique doesn't work for an individual, she or he shouldn't give up. And, obviously, don't let anyone tell you there is only one 'correct' way to do something.

The Light Farm is still trying on ways to make good information as easily accessible as possible. The thymol/ 600/ 200 issue is a case in point. I would like your permission to post your observations about surfactants on TLF. I know you don't have time to be a TLF Contributing Editor, but it would be an appreciated additional bit of information. If you want a precise quote, give me something to copy and paste out of a response to this post.

Thank you,
d

Ryuji
04-14-2008, 05:06 PM
"Coating defects on papers can be caused by inadequate mixing when adding hardener, or can be caused by ineffective surfactant. The surfactant used in Photoflo (octylphenol ethoxylate) is not very effective for coating purpose, unless you coat slowly, or make multiple strokes (like when using brush). If you have no access to a better surfactant, try to wet the coating surface with plain dilute surfactant, immediately before coating the emulsion."

You are probably referring to Photo-Flo 200, the form of surfactant most commonly used in the home darkroom as the final step in film developing.


PhotoFlo 200 and 600 both use the same active surfactant but at different concentrations. I found it to be inferior to some other surfactants that are designed for coating applications. Octylphenol ethoxylate (the active ingredient of PhotoFlo and traded by the name Triton X-100) is also non-biodegradable and a estrogen analog that seriously affects aquatic organisms. But it is also true that some of the better surfactants are not readily available.

Most high speed coaters used in the industry require emulsions added with anionic surfactant (such as Triton X-200) and a small amount of fluorosurfactant. These surfactants together work very nicely even when coating slowly.

I have a yet another way of coating my emulsion using a wire wound rod. Now my wire rod is getting old, I'm replacing it with yet another simple tool. I'll report it when I get a few tests done.



re: pepper fog: It's been my experience that pepper is primarily a problem of uneven silver addition during the precipitation step.

This is actually a factor related to gelatin, agitation and the kettle shape/size. If agitation is very vigorous and more dilute silver jet is added very slowly, pepper is less likely to occur, but then if you use a gelatin that has stronger peptizing power, pepper fog is far less problematic under the same mixing condition. So everything is related. One another point is the shape of the mixing vessel, especially if your batch size is large. Regular cylindrical beakers are not very good because there is a region of ineffectively agitated area near the bottom edge. Something like cooking bowl shape is best, although ones made from opaque nonmetal materials are hard to find (it has to be nonconductive material to be compatible with magnetic stirrer you use).

When you make batches of emulsions, what is very helpful is to look at them with microscope and see the size distribution and shapes of the crystals.

Photo Engineer
04-14-2008, 05:38 PM
Denise;

I don't remember the note, but I do know now that it is not an interaction with the Thymol solution.

I believe now that it is the fact that PF600 is more concentrated, and even a tiny error can cause too much or too little to be added. Due to the small batch I was using, I believe that I was not adding enough or adding too much. You know how viscous it is.

In any event, either Photo Flo 200 or 600 works.

Kodak uses 3 surfactants for the most part, TX-100, TX-200 and Saponin. Saponin is expensive and hard to dissolve as well as somewhat prone to going bad even refrigerated. TX-200 is sold as a suspension and is sometimes difficult to get an even distribution. If you notice on the bottle of it I sent you, I say "shake well before use" or something to that effect. TX-200 is also anionic (has a negative charge) and subject to some degree of viscosity change in gelatin and it can interact with some addenda. It is avoided in some types of coating due to the side effects.

All of the above has led me to use TX100 and sold as Photo Flo 200 with some other ingredients, it is ideal. It also has some other good properties that I pointed out in class. I'll go into them in a major way on APUG here as soon as I can get the data together.

There are cationic surfactants, but I'm not aware of ever having used one at Kodak.

There are families of foam reducers, but the Everclear you add is probably one of the best. At Kodak we used plain old t-Butyl Alcohol to mist the surface of melted gelatin just as you use Everclear. However, it is expensive as well and can solidifiy at near room temperature.

You are 100% correct though. I've made my emulsions in 3 places, and I get the same result here over and over, whereas they are 'different' at the other sites. I have slightly different speed and contrast when I make it other than at home. But, it is just a matter of a few tweaks, as you found and as we discussed way back when.

As I say, use what works for you.

As for the AJ-12 (I believe that is the number), formula that Kodak published, well it was published back in the days of active gelatins IIRC, and so it has no sulfur or gold in it. A modern version of that formula is used today in KRL for hand coating experiments and for testing new chemicals as it responds well to a number of B&W and color processing conditions. I used an analog of that formula almost exclusively for tests, until I was ready for the 'real thing'. It is slow and can be handled under rather bright yellow safelights yet it has a camera speed and contrast that are useful. I believe that it can be used with noodle washing and survive well, but IDK how it is actually washed for our use. I just ordered "Lab Simplex" in big cans. The stuff we used was quite reliable and with sulfur or sulfur + gold, it can be boosted to quite a reasonable speed.

PE

Photo Engineer
04-14-2008, 07:36 PM
Denise;

After looking up my data and also re-reading Jim Brownings web site on emulsion making, we seem to be in agreement in that flat bottomed beakers work up to at least 1 liter. Magnetic stirrers work up to about 500 ml, and above that a prop mixer should be used. See the illustration on Jim Browning's web site.

It is a matter of rate of mixing, which if adjusted and done with the right mixer, will eliminate any dead spots. For example, with a 1/2" stirring bar and 500 ml of emulsion, there is dead space, but with a 2" stirring bar there is, for all practical purposes, no dead space. That same 1/2" mixer will work fine with 100 ml of emulsion.

If you go to larger makes, then you use the prop mixer, but as container size increases, the blade size must also increase and mixing speed must be adjusted. In addition, it is entirely feasible to use more than one mixer such as a prop and a magnetic mixer.

I might add that Kodak making kettles became flatter as the size increased, and the mixer size and rpm values changed as well as noted above. Also, auxiliary mixers were often used during some special operations to assist the main mixer. These were labeled MIX and AUXMIX in formulas.

When you use a hot plate, you should use a glass beaker to keep the temperature more uniform throughout the container, as the use of metal will allow large temperature drops as you move away from the heated surface towards the top of the container. A metal container is fine if you use a water bath, but this becomes difficult if you must reach temperatures much above 40 - 45 deg C. Many makes require 60 - 90 deg C. Of course, you can use a water bath on a hot plate with a metal beaker which is another option.

So, these are some things you may find useful.

PE

Kirk Keyes
04-15-2008, 01:02 AM
Guys and gals -

Remember that there are different types of beakers. I picked up some "tall form" beakers, 400 and 600 ml. They have a smaller footprint than a traditional beaker. And as Ron mentions, there are many different styles and shapes of stir bars. I king of like the finned ones, but I think I used a 1 1/2 inch one which reaches across the bottom of my 400 ml beaker pretty well.