Need advice for engaging dry plate.

[Pere Casals]

Last six months I've been reading all I found about emulsion making and dry plate coating.

For the moment I've ordered Colloida P gelatin, Silver nitrate, KBr, Amonium bromide, Thymol, Erythrosine, and Pinacyanol, some arrived yet.

>> I concluded that I've to drop around 25ml of fresh emulsion on each 8x10 glass, this will be 0.5mm of fresh emulsion over the plate, then it may end in 0.05 after dryed. Is this right?

>> Also I'd like to know if somebody has practical experience by using a good and fast emulsion recipe and dye sensitization, and what dyes proportions. I concluded that I have to go to amonium emulsions if Pinacyanol sensitization is to be employed. Something better than TLF 1/2?

>> I'd like to know about dye combinations to obtain faster panchromatic emulsions...

>> I'm buiding a cabinet to mature the plates with controlled temperature.

>> I'm thinking in using an Airless paint sprayer to coat the glasses inside a box at some 35ºC, to avoid gelification inside the sprayer, can this be viable? I'm thinking in a "paint flow" of 100ml/min so it would take 15s to throw the guessed 25ml spread on the 8x10 glass...

[koraks]

No experience here, but I've read quite a bit about emulsion making as well. I never saw a clue that dyes do much to enhance sensitivity; they only affect spectral response. Controlled ripening of the emulsion and the rate at which AgNO3 is added seems to be the key to higher sensitivity, as it affects grain size.

Also, the TLF recipes are tried and tested. Even if they are too slow for your taste, why not try to walk before you try to run a marathon?

Spraying seems like a messy way to coat plates with a great potential for unevenness and emulsion all over your coating area. What's wrong with pouring?

[Robert Brazile]

I've been working with dry plate emulsions since taking the workshop at the Eastman Museum a while back. I actually have some of the same questions you have, because I've concentrated on mastering the various steps and learning about exposure and development before moving further into working with speed, ortho/pan sensitivity, and other coating methods.

That is, I'm still doing the basic color blind recipe and pouring plates by hand, and while it's really not difficult, it's taken me a while to get the hang of it. While you can certainly jump in where you're thinking, it seems to me you're multiplying a bunch of variables that will make it a bit more difficult to master, whereas a methodical, step-by-step approach might get you to the same place faster in the end.

That having been said, experimenting with erythrosine should be simple enough; my plan is simply to get the other stuff nailed down first.

By way of example, my most recent plate (color blind, hand poured, VERY slow):


I4P-041, Two portraits, #2 by Robert Brazile, on Flickr

Robert

[jnantz]

nice work robert !

===

pere

go to the light farm, buy denise's book
there is a lot there.

you might be looking for trouble with a paint sprayer..
sounds like it will be a complete mess
coating by hand or coating rod/blade/pour/brush &c is the way to go
i've coated glass by hand/pour and brush it really isn't as hard as it seems.

[DHodson]

Another vote for Denise's book - The Light Farm: Handmade Silver Gelatin Emulsions. It's well written and a great resource (available from Blurb though her website)

http://thelightfarm.com/

I don't have any experience with a sprayer but I'm wondering how you'd manage air bubbles in the emulsion. I'm just starting out with glass (4x5) but there's a section in her book on coating glass negatives and I'm in the process of putting together the coating station she describes. So far it's been pretty straightforward and will let me coat a bunch of negatives at once.

[mdarnton]

I don't have emulsion experience, but I do spray a lot of varnish through an airbrush, and I think you do not want to spray.
1/ It takes skill--lots of skill.
2/ 25ml in 15 seconds is way too fast--you will have a mess, and runs
3/ In order to coat full thickness right up to the edges, you are going to have to spray beyond the edges, and I will guess that you would lose half your emulsion coating the background support beyond the glass to make sure the glass is fully coated right to the edges.

I'll guess if spraying was the easier and better way, everyone would have figured that out by now.

[Pere Casals]

No experience here, but I've read quite a bit about emulsion making as well. I never saw a clue that dyes do much to enhance sensitivity; they only affect spectral response. Controlled ripening of the emulsion and the rate at which AgNO3 is added seems to be the key to higher sensitivity, as it affects grain size.

Also, the TLF recipes are tried and tested. Even if they are too slow for your taste, why not try to walk before you try to run a marathon?

Spraying seems like a messy way to coat plates with a great potential for unevenness and emulsion all over your coating area. What's wrong with pouring?

A basic dye sensitization may increase speed by 2x to white light, not sensitized emulsion is only blue sensitive (well, if using some KI it has some green sensitivity) as sensitized emulsion also takes green and red photons, before sensitization those photons were lost.

Of course, the ripening is key...

OK, I'll start pouring...

[Pere Casals]

I've been working with dry plate emulsions since taking the workshop at the Eastman Museum a while back. I actually have some of the same questions you have, because I've concentrated on mastering the various steps and learning about exposure and development before moving further into working with speed, ortho/pan sensitivity, and other coating methods.

That is, I'm still doing the basic color blind recipe and pouring plates by hand, and while it's really not difficult, it's taken me a while to get the hang of it. While you can certainly jump in where you're thinking, it seems to me you're multiplying a bunch of variables that will make it a bit more difficult to master, whereas a methodical, step-by-step approach might get you to the same place faster in the end.

That having been said, experimenting with erythrosine should be simple enough; my plan is simply to get the other stuff nailed down first.

By way of example, my most recent plate (color blind, hand poured, VERY slow):

Robert

Great result !!!

I'm just to follow your way: step by step. I'm near prepared to make first batch of emulsion, and then like you, I'll try to improve the emulsion.

It looks that erythrosine can be added in the B part before mixing, after washing with Thymol, or after coating by bathing the plates.

If added in the beginning it is not wased out later, well... it is washed but the erythrosine tied to chrystals remains, so no problem.

Just I was asking to prepare next step.

Great portraits!!! it has the antique look of a blue filter, of course, anyway I see a great result, very nice !

[Pere Casals]

Another vote for Denise's book - The Light Farm: Handmade Silver Gelatin Emulsions. It's well written and a great resource (available from Blurb though her website)

http://thelightfarm.com/

I don't have any experience with a sprayer but I'm wondering how you'd manage air bubbles in the emulsion. I'm just starting out with glass (4x5) but there's a section in her book on coating glass negatives and I'm in the process of putting together the coating station she describes. So far it's been pretty straightforward and will let me coat a bunch of negatives at once.

For the moment I've read all that's in the TLF site, and also I was planning to buy the book, also I was considering "PHOTOGRAPHIC EMULSION MAKING, COATING AND TESTING" BOOK & DVD'S BY RON MOWREY, as a ISO 40 panchromatic emulsion is described. I guess I need both...

I don't have emulsion experience, but I do spray a lot of varnish through an airbrush, and I think you do not want to spray.
1/ It takes skill--lots of skill.
2/ 25ml in 15 seconds is way too fast--you will have a mess, and runs
3/ In order to coat full thickness right up to the edges, you are going to have to spray beyond the edges, and I will guess that you would lose half your emulsion coating the background support beyond the glass to make sure the glass is fully coated right to the edges.

I'll guess if spraying was the easier and better way, everyone would have figured that out by now.

OK, I'll try pouring, and then the coating station described by Denise.

[DHodson]

It's nice that you can read the book on the Blurb site if you want to have a look at the section on coating glass negatives (P46).