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Dry Plate Newbie

Herzeleid

Member
Joined
Oct 31, 2008
Messages
386
Location
Ankara/Turkey
Format
Multi Format
Hi everyone,

I dabble in various alternative process and wet collodion, but I recently gave up on making collodion negatives. Although it is far easier to have ambrotypes and tintypes, time and effort wise it is very frustrating to have clean and problem free negatives. So I decided to try making silver gelatin emulsion to coat on glass.
I read a lot of the posts here and read many articles at the lightfarm. My first attempt was not washed adequtely, I had crystals on the surface and extremely slow emuslion. Luckily at the second attempt I had clean plates but this time I had quite thin images and also long exposure times.

The problem is due to my hand coating method, I poured so much of the emulsion from the plate as if I am making collodion plate. I think I can remedy that in my next attempt.

I follow the formula from thelightfarm, modified AJ-12. I also use chrome alum and thymol. I use food grade gelatin so I aim no to exceed 50C during ripening and digestion. I measure fog around 0.1D, however I cannot trust it yet without making a proper problem free coating. I have used Parodinal 1+10 for 10mins to develop the plates.

I have erythrosine, tartrazine and eosinY so I will definitely attempt at orthochromatic sensitization at some point.

I am open to advice at the moment. Is it a practical way to gain speed with sulfur sensitization. Faster precipitation followed by a sulfur sensitization with thiosulfate.

Regards
 

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I suggest using something like D76 as developer and using a gel content of about 8% in the coated material. Try getting some gelatin from Fotoimpex in Germany. Food gelatin has additives and the viscosity is often too low.

PE
 
Photo Engineer said:
I suggest using something like D76 as developer and using a gel content of about 8% in the coated material. Try getting some gelatin from Fotoimpex in Germany. Food gelatin has additives and the viscosity is often too low.

PE
Click to expand...

Thanks a lot PE.

I forgot to mention gelatin I am using is 250 bloom, viscosity seemed fine but I will increase it to %8 as you recommend. I have also inert photo gelatin from silverprint.co.uk, I am thinking of keeping it for further emulsions, when I gain more understanding of controlling the variables.

I just finished building a peristaltic pump with basic pwm, 8 to 100ml per min. flow rate.

I can mix some ID-11, I think I also have perceptol and DD-X.
 
I am surprised because food gelatin is usually about 70 - 80 Bloom. The 250 is often considered too "chewy" by some. Food gelatin also often contains drying agents to prevent caking. These can affect precipitation of the emulsion.

PE
 
Photo Engineer said:
I am surprised because food gelatin is usually about 70 - 80 Bloom. The 250 is often considered too "chewy" by some. Food gelatin also often contains drying agents to prevent caking. These can affect precipitation of the emulsion.

PE
Click to expand...

I buy it from a chemical supplier, they also have 80 bloom that is categorized as clarification gelatin, for juices and etc. I checked mine now it says 240 bloom, not so far from my early assumption.
 
I am getting slightly better plates now. I am using photo grade gelatin for making Mark Osterman's dry plate formula.
What would be the typical maximum density I would expect from a properly coated dry plate? I feel like I might be underexposing or my gelatin is too hard and it swells less and prolongs development and fixing.
I already halved the chrom alum amount.

 
Dmax should be between 2.0 and 3.0 on a step wedge. You should develop until you start to see a fairly good image on the reverse side of the plate. That indicates both good exposure and processing.

PE
 
Photo Engineer said:
Dmax should be between 2.0 and 3.0 on a step wedge. You should develop until you start to see a fairly good image on the reverse side of the plate. That indicates both good exposure and processing.

PE
Click to expand...

The image on the reverse side of the plate, that was the thing really bugging me. After 10 and 17 mins (1+1 and 1+3 perceptol respectively) of development the yellow emulsion color still dominates the glass side of the plates. It is like the developer did not penetrate all the way down.
I did a test by putting a 21 stouffer on to the dry plate and another glass on top. Turned on the lights and exposed 2 mins, developed 10mins and finally achieved Dmax 2.1 in step 1, (BF is 0,33).
Fixing also takes 10mins or longer, I check the glass side of the plate to ensure fixing is finished. (I use TF-2).

Do you think I should reduce chrome alum further? I prefer not to eliminate it completely.

Regards
 
The chrome alum level is probably not the culprit here. The image on the back should be mostly the high density areas. It is not a replica of that on the front. You might try D76 or something like it. A solvent developer like that might work better. The Dmax is a bit low.

PE
 
I will make a new batch of emulsion and check the glass side for high density areas during development. I will also prepare ID-11 and probably use it at stock dilution.

Thank you
 
10 minute fixing time is reasonable but at the high end. Rapid fixer should clear in about 2 minutes. Might mean your coating is thick.
 
Nodda Duma said:
10 minute fixing time is reasonable but at the high end. Rapid fixer should clear in about 2 minutes. Might mean your coating is thick.
Click to expand...

I thought that fixer should clear faster. Sometimes it takes a few minutes longer. I am out of rapid fixer to test it at the moment.
I will have to prepare a new batch for testing. I coat 25-30 ml of emulsion over 10x10" plate.
 
Herzeleid said:
I thought that fixer should clear faster. Sometimes it takes a few minutes longer. I am out of rapid fixer to test it at the moment.
I will have to prepare a new batch for testing. I coat 25-30 ml of emulsion over 10x10" plate.
Click to expand...

The hardener that you add makes it more difficult for the chemicals to diffuse into the emulsion, so everything is going to take longer. The hardener isn't absolutely necessary to add to the emulsion if you maintain constant temperature throughout and process (develop, stop, fix, wash) the plates between 18-20C. I would add hardener to the fixer so that the emulsion will adhere better during washing, but you can do the same thing with a subbing layer (1000 ml water, 5g gelatin, 0.5 g chrome alum. dip washed plates in solution and let dry, then coat).

Also, 25-30 ml is a little on the thick side...you can get your entire density range with less emulsion. Try coating 10" x 10" with about 20 ml (0.25 ml / sq inch) of emulsion.

Honestly, though, sounds like you're getting good results so that's 90% of the way there.

-Jason
 

Thanks a lot Jason, I will try thinner coats next time. The photo-grade gelatin is quite strong and hardening it makes it very resilient. I will compare development and fixing of unhardened plates.
Subbing is an extra step that I prefer not to do but I would try it eventually. Actually the way you describe it, can it be used to make a dyed anti-halation layer?
I was reading photographic emulsion technique by Baker, I recall sodium silicate and chrome alum was the industrial subbing for dry plates. I have the materials for that too but I will have to search for an ideal dilution.

And thank you for your kind words. All the information people share on this forum makes it possible.

Regards
 
The subbing layer I mentioned comes from Wall's Photographic Emulsions, 1929. It's not as complicated as using sodium silicate and much safer. Dunk and dry. I've never messed with anti-halation... the halation glow on the highlights is one of the characteristics of dry plate photography that I like.
 
I agree halation is one of the dry plate characteristics, but in case if one needs to make an anti-halo layer.
 
The Light Farm desperately needs a topics index. Someday!

A yellow layer may help. I've never tried. Turned out that the backing sheets work so well and simply that I never went further. Mostly, I just love halation.

One factor to take into consideration is what your end goal is for a plate. If you are planning on scanning it, an integral backing won't matter. If you are going to be contact printing the plate on most papers, a yellow layer between the light and the emulsion layer would prevent exposure. However, if the paper you use is variable contrast, it might be interesting...um, must think on that one. Intriguing.
 
When making salt prints, I used various coloring substances to effectively see silver nitrate coating. I have used tartrazine with silver nitrate too. It did not have any effect, but silver emulsion is completely different matter.
Actually I was expecting that it would filter some UV rays and may be used for contrast control in some cases.

I will eventually use my dry plates for salt and carbon like processes. In collodion literature, there are some varnishes contain a few grains of iodine dissolved, its yellowish color slows down UV penetration.
It works similar to pyro stain in that sense. Just thinking may be, I might try and see how it works.
 
Tartrazine works, but when used as an undercoat, the dye diffuses into the emulsion and causes a speed loss. With spectral sensitization, you have to use an orange or grey/black dye.

As for hardening slowing any reaction whether development or fixing, Chrome Alum is probably not the culprit. It is more useful in bonding the plate to the gelatin. Formalin or Glyoxal might be another matter. I think it might be more of a problem of "dead grains". These grains arise from lack of sensitivity in the emulsion. If there is something wrong with any part of the process or chemicals this can arise. It was the cause of the need to coat high silver or silver rich emulsions in the early days of photography.

PE
 
Well it was a nice thought. I might give it a try to see how it effects the results

I might be doing something wrong in the processing, that is more likely. But I still feel penetration of chemicals is slow. I will consider and try to test all your valuable advices.

I have no reason to doubt the chemicals, I used the same salts and silver in wet collodion negatives and positives. I use the same supplier for years.
I set up a peristaltic pump with PWM motor controller and variable voltage controller, so the rate of silver is relatively similar from batch to batch.
I admit I haven't monitored temperatures very meticulously in ripening and digestion steps. I need to make tests with my hot plate, how fast it reaches required temperatures.

Regards
 

I am hijacking my thread but anyway.
A follow up on the idea after discussing anti-halation layers and collodion varnishes that has iodine in them to increase UV density.
I was wondering how tartrazine would effect UV penetration, and its effect on alternative processes. So here is an initial test.

Yellow patch is %10 gelatin %0,8 Tartarine
Red Patch is %10 gelatin %0,8 Tartrazine + %0,8 Erythrosine


As expected red is more effective, may be too effective, if we overlook the unevenness in my gelatin coating.
So I can assume that after fixing and washing a dry plate immersed in tartrazine dye or tartrazine+erythrosin dye combination will block more UV light giving the negative pyro-stain like property.
I am guessing dyes won't last long under prolonged UV exposure, but this might be a good trick to remedy the negatives if chemical intensification fails.
I will have to test it with a real dry plate negative later.

Regards
 
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