Just so everyone is on the right page, this workshop will be about making “Dry Plates”, which includes learning how to
All the methods discussed will be mine, personally, and are not necessarily the only way to do them. Other options are sometimes mentioned as a note or in the Appendix, as are discussions and outcomes from the winter ’06 workshop sessions. It will be a bit of what I call “kitchen table chemistry”. Since the making of a dry plate will require a number of different skills, it does not, in my opinion, lend itself to a simple single-day workshop, so this two-day workshop was designed.
You might want to practice coating plates the size you will use before attending the workshop or mixing emulsion. You can do this until you get good, even coverage to the edges of the plate. Just mix some store brand gelatin and water to the same ratio as your emulsion (1:24 or 1 ounce gelatin to 500 mL water) and add a drop or two of food coloring (not red), so you can see it on the plate. Mix your gelatin with cold water, let it sit for a couple of minutes, and warm until the gelatin melts. Then, practice coating until you are able to repeatedly obtain an even coat while working under a safe light. You can easily clean the gelatin off the plates using a little hot water with some bleach added.
You do not need to have a view camera to participate in this workshop. There will be cameras for use or
If you are going to use the plate for an enlarged negative or lanternslide, all you need to do is to have the store cut single strength glass to the size you want to enlarge to.
Like most of the historic (alt) processes, making glass plates has many process steps, during any of which things can go wrong. If you want consistency between plates, you need to maintain a higher-than-normal level of “process control” and lab cleanliness. This is not beyond what you can do. But fear not. If you have a relaxed sense of process control, or work on the “kitchen” table, you can still make plates. You are just more likely to have a greater variance between emulsion batches.
Contrary to what the “Zonies and Techies” will have you think, photography is not an exact science. There are so many variables that go into each attempted photo, from inspiration to finished image that one should roll with the punches and not always try to control things too much. The batch-to-batch variations that you get with making your own emulsions can be minimized, if you are willing to work in laboratory conditions and use stringent process control. If, like me, you are not willing or able to do this, you can still make great images with your own emulsions and have fun doing it.
Some folks might wonder about the level of hazardous chemicals that we use to make dry plates. Compared to many of the other historic processes (and wet plates, especially), most of the chemicals we use are rather benign. The most dangerous chemicals are the silver nitrate and the ammonia, if it’s used. You must keep the silver nitrate out of your eyes and do not breath the dust, as it readily attacks your mucus membranes and can cause blindness. It also will permanently stain your skin and clothing, where contact is made.
The Ammonia Type solution was tried with household ammonia in the first session and found to be ineffective. Therefore, it requires industrial strength ammonia, which requires care that you not inhale it while handling. Skin contact could also be a problem, especially if you are already sensitive to it. Keep it out of your eyes and do not drink it. I have not tested this process using industrial strength ammonia. Refer to Appendix – Emulsion Recipe Options.
MSDS for the chemicals will be available for anyone who wants to review them. Refer to Appendix – Safety for more information.
Cutting the Glass
Measure twice. Cut once. Measure the holder you will be using because they all seem to vary. There is more than one “standard” size for half-plate (and other size) negatives. Make sure your glass fits your holder.
Once you have the glass cut to the correct size, take a ceramic knife-sharpening stick or a glass-sanding block or stick and run it along the edges of the glass to knock off the sharp edges. (I also knock the sharp edges off the corners.) You need to be very careful at this stage or you WILL cut your hands later while working with the plate.
Cleaning the Glass Plate
This method works best if you have running water to wash your plates and a separate, clean place to allow them to dry.
Place the glass plates under running tap water to wet them, then sprinkle on the dry cleanser and rub/scrub the plate, both sides, with your bare hands. By doing this you are also cleaning the oils off your hands. After a good “scrub up,” rinse the plate front and back under the running water and place on its edge in a rack. After the plates are clean, rinse them off with a little distilled water, then dry them, either with a lint free CLEAN cloth, or put them back into the rack to air dry. Note: Refer to Appendix – Cleaning 1. b. i. and POST DRY PLATE WORKSHOP DISCUSSION Second Session, Bullet 2-2, for discussion on this topic.
Refer to Appendix – Cleaning, for a dry cleaning method and information on how to remove emulsion from plates for re-use.
If you are using Mylar, acetate, plastic, metal, or some other substrate, you will need to find an appropriate cleaner. The plastic-type substrates tend to scratch easily. Also note that many of them are dimensionally less stable and have a shorter lifespan, unless dropped, than glass.
Making a Silver Gelatin Emulsion
This section includes information from other sources, including unblinkingeye.com, and personal and workshop experience.
This is the part of the process where you can spend a lot of time trying to get the desired results. For your first emulsion, something that is light sensitive with low fog should be the only result desired. Though this is not too hard, there are no guarantees. Making emulsions is a science, BUT there is also a little voodoo involved. Very small changes in your process or materials can make a big change in how the emulsion behaves. Emulsions have more in common with baking than most of the other historic processes. Any change in the process can make a noticeable difference in the goods.
Stated simply, the process adds silver nitrate to a mixture of gelatin and a halide. The first step in making emulsion is to heat a mixture of gelatin and your halide of choice in the mixing kettle. Then add the silver nitrate (mixed in distilled water) to the halide mixture at a rate to get your emulsion close to the speed/contrast desired. The speed at which you add the silver to the halide will set the base speed of your emulsion. Adding the silver quickly gives you a slower emulsion; adding it slowly gives you a faster emulsion. The slower the emulsion, the higher the Max-density range.
You will then ripen this mixture at the correct temperature to grow the silver halide grains, which increases the speed of the emulsion. Next, you will wash the emulsion to remove the remaining reaction products. Then you will reheat the emulsion, during which time you can add “extras” (contrast agent, dye sensitizer) to further modify the emulsion to your requirements. Finally, you will coat the plate, allow it to cool until the gelatin sets, then dry the plate for use.
Every batch of gelatin will be different. Some make a faster emulsion, others a slower emulsion. The amount of time you take to add the silver nitrate [Refer to Appendix - Emulsion] will affect the speed and contrast of the emulsion, as will the temperature at which you mix it. The choice of halide will greatly affect the spectral sensitivity of the emulsion as well as the speed. The amount of time and temperature the emulsion spends ripening will affect the speed and fog level of the emulsion. The efficiency of the washing stage will also have an effect, as will any additives introduced after the washing stage or the after-ripening stage. As you can see, there are many things that will affect the end result.
There are two main ways to mix your emulsions, either in “large” batches, where you coat a number of plates with the same batch; or, if your process control is good, you can make small batches and only coat a couple of plates at time. I normally make a batch large enough to coat 10-20 plates. This allows me to test a few plates to determine the speed and then have a number of plates available to shoot at that speed. If you use the same batch of gelatin, same batch of chemicals, same batch of distilled water, and the same process to make your emulsion you should have a good starting point for your different batches. Do not expect them to be as consistent as modern manufactured film, though they might be as consistent as the manufactured liquid emulsions.
* The xx in the halide section is there to allow for your choice of halide, i.e. sodium chloride, potassium chloride, ammonium chloride, etc. You can even use table salt (sodium chloride), or if you have potassium bromide in the darkroom, it will work as well. H.J. Wall, in his book How Photography Works, explains halides.
“The majority of silver compounds are photosensitive, but for nearly all photographic purposes three suffice; silver chloride (AgCl), which is used for slow (contact) printing papers; silver bromide (AgBr), which is used in negative emulsions and in fast enlarging papers; and silver iodide (AgI), small quantities of which are used along with the bromide in fast negative emulsions.
“As the elements chlorine, bromine and iodine belong to the group known collectively as the halogens, the three compounds are sometimes called generically silver halides. However, the bromide is photographically much the most important silver halide, and by far the most experimental work has been done with it. Therefore, a reference to silver bromide is often taken to mean “silver bromide or other halide or mixture of halides.”
Silver chloride emulsions are sensitive to UV and “light” blue ~350-430nm,
Now that we’ve had an overview of the process, let’s get down to bid’ness. The base recipe for the neutral type emulsion used for this workshop is listed below. It is known as an iodobromide film emulsion from James & Higgins’ Theory of Photographic Process, 4th edition. By changing only the halide in this base emulsion, you can also make a bromide emulsion, a chlorobromide emulsion, or a chloride emulsion. The big difference between these emulsions is in their spectral response. Each is sensitive to slightly different wavelengths of light. (See Notes above.)
I prefer to use the word recipe, not formula, since emulsion making is much like baking. There are a lot of different recipes out there for pizza crust and they all give different results. EVEN when made from the same recipe, by the same person, in the same way, they are often different.
Neutral Type Emulsion
Refer to Appendix – Emulsion, Recipe Options, Calculator, for a spreadsheet that will calculate these ingredients based on the amount of silver you want to use.
Before you begin, weigh the different chemicals and keep them handy. Make sure the water bath is at the correct starting temperature of 70ºC.
1. Mix up the halide/bromide solution. Make sure it is at the same temperature as the water bath.
Note: The ethanol solution flocculates (gathers or coagulates loosely; precipitate from solution in the form of fleecy masses) the bromides and nitrates; decanting physically removes them. A centrifuge might also work to remove them from the solution. Safety Note: Most everyone in the first Session got “high” from the gaseous exposure to ethanol, which was heated in solution, going into the blood stream at a faster rate. A good ventilation system or wearing personal protection equipment (e.g. a 1/2 mask respirator) would help tremendously.
7. Add the Extra gelatin & H2O (emulsification) and “after-ripen.” Heat the emulsion slowly. Do this at no more than 60ºC for no more than 30 minutes. During this time, you can test. (Refer to the next step.) Adding a very small amount of a very weak hypo solution greatly increases the emulsion’s speed. Cool the emulsion slowly, to 40ºC. Caution! This step can build fog in your emulsion if the temp is too high and/or the time is too long. So it’s best to keep this stage short and on the cool side. The after-ripening does not noticeably increase grain size, but it does increase speed.
8. Test. It is best to do this during the after-ripen (previous step). Spread a thin layer of the emulsion on a piece of paper strong enough to withstand development. Allow to dry. Cut the paper in half. Expose one half; develop both halves. The exposed half should be black, showing that the emulsion is sensitive. The unexposed half shows you the fog base.
To work for more speed in your emulsion, you will need to control your exposure and do multiple tests. Continue to after-ripen (previous step) until you first notice fog develop. Immediately stop the after-ripen and coat your plates.
Another way to test only for fog is to put a drop of emulsion, every few minutes, into a clear beaker with strong developer in it. When it turns light gray, the fog level is adequate.
Note: Due to time constraints, workshop participants began coating while the test sheet was drying. No “extras” were added to the emulsion.
9. Coating the plates. Immediately before coating your plates, you can add hardener to the emulsion, if desired. To coat a 3½ by 4½ inch glass plate, you will use approximately 4 mL of emulsion. Hold the glass plate level, pour on the solution, and spread it uniformly.
10. Chill & Dry. Place the coated glass on a level cold surface in the dark, until the emulsion sets (approx. 10 min). You can also use an inverted bowl in the freezer (without a light) or the top of a contained ice block in a cooler. Then place in the dark to dry (hours).
11. Expose. Make your first test exposure, shooting a scene with bright white and shadow areas for range, at 1/30 second at f/8, and adjust up or down as necessary. If possible, expose ½ or 1/3 of your plate at a time, giving you multiples of the exposure on one test plate. ASA – Session 1 = 5 (nearly about); Session 2 = 2 NOTE: The iodobromide emulsion is sensitive to blue, the same as wet plate negatives, so medium to light blues will wash out.
12. Develop. Develop in an active developer such as Kodak D-8 (2:1), HC-110 (Dilution A), or Dektol (1:1). See Appendix – Develop, to see some negatives.
Chemical suppliers per web as of June 2006
James, T.H. & Higgins, George C; Fundamentals of Photographic Theory. 1968: Hastings-on-Hudson: Morgan & Morgan, Inc.
Wall, E.J: Photographic Emulsions. 1929: New York: Oxford University Press (Oxford series in optical and imaging sciences, vol 8.) London: Chapman & Hall – their preparation & coating on glass, celluloid & paper, experimentally on the large scale.
Most chemical supply companies and many universities with chemistry programs have free Material Safety Data Sheet (MSDS) search engines. Two places to look include:
For a free sheet of Mr. Yuk stickers, send a self-addressed,
Free Mr. Yuk Stickers
Clean the glass
1. Dry method of cleaning glass. Scully & Osterman used this method at their wet plate workshop. You can use a product called Glasswax or a supersaturated mixture of calcium carbonate in water. Mix it in a small-mouthed container, such as a dish soap bottle with a flip-top cap. You need to shake well before each application because the particles settle quickly. The cleaning process can be done without additional water, besides what is mixed in with the calcium carbonate. (Terry H does not endorse this process, since it was not tried when making dry plates.)
i. Cut glass
i. Stage 1 – With glass laying on a rag, apply a small amount of cleaner to the glass. Using another rag, spread it around applying substantial pressure. This is to remove any residue from the glass and to give it a “tooth” to hold the emulsion. Additional cleaner may be applied, if necessary. It is not necessary to remove all of it at this stage. Flip the glass and repeat on the other side. Pick up the glass by the edges only and move to the next stage.
ii. Stage 2 – With the glass laying on a rag, use another rag to remove remaining cleaner from the glass and begin polishing it with strong circular motions. Flip the glass and repeat on the other side. Pick up the glass by the edges only and move to the next stage.
iii. Stage 3 – With the glass laying in a glass vice or on a lint-free rag, use another lint-free rag to continue polishing the glass. Do this until to you can breathe onto the glass and no marks, streaks, or unevenness appear in the condensation. Using the cloth to hold the edges of the glass, move it to the rack. If you have determined that one side of the glass is better than the other, face that side to the left in the rack.
2. Cleaning glass with bad emulsion/negative on it. – You can easily clean the emulsion or practice-gelatin off the plates using a little hot water with some bleach added.
Click here for the Emulsion Calculator (.xls file).
Chart found on page 28 of James’ & Higgins’ Fundamentals of Photographic Theory.
First, weigh the different chemicals and keep them handy. Make sure the water bath is at the correct starting temp, 50ºC. Then,
mix up the halide solution and make sure it is also at the same temp as the water bath, 50ºC. Now the fun starts. Under safelight,
take half the water, at 50ºC, for the silver solution and add the silver nitrate to it, making sure it completely dissolves. Now, using
a very controllable device (eyedropper for example), start adding ammonia to this solution. With the first drop of ammonia, the
clear silver solution will become cloudy/opaque. Continue to add ammonia, drop by drop, until the solution becomes clear again. Measure the solution’s volume and add water to make up the remainder of the amount needed. To use this method you need
ammonia that is much stronger than what you can find at most stores. In other words, you need industrial grade ammonia. Because of this, we will not make this type of emulsion in the workshop.
For process instructions go to http://unblinkingeye.com/Articles/Emulsion/emulsion.html.
Post Dry Plate Workshop Discussion
First Session did the alcohol/ethanol wash: lost much emulsion and it was very watery.
Discussion of whether you can develop these in pyro (You can under a green inspection or normal safe light, per usual.)
Some of the images had a dull "pink tint" as if they had been toned. Re-fixing helped reduce the redox (reduction-oxidation) process in one of Stephanie's plates. Be aware that you can over-fix and loose your image, too. The color could also be a reaction to the chemistry used or the thickness of the emulsion layer.
DARKROOM - The space used for the Session 2 was excellent. It is located on East 3rd St at Chicon and managed by Scott (512-542-9261). We rented it for a fee per attendee. Usually it is rented for a monthly usage fee. Scott was very helpful to make the space as usable for our workshop as possible. It’s also within walking distance of Azul on 1st St at Chicon, and Café Mundi on 5th St between Chicon & Comal. Otherwise, it is a darkroom & gallery/studio space with multiple B&W and color enlargers, a large UV exposure box, a large L-shaped wet processing sink, and a 16x20 screen print dryer that holds at least 8 prints. (I’m sure there are other amenities that I’m missing here.)
General Questions for the Workshop Participants:
1. I was thinking of restructuring the document to be more of a process to follow, with comments for each process step about what was done & the results for each session. What do think about this?
2. Do you think information in this document that wasn't actually used should be moved to the Appendix?
3. Do you have any other comments you want to make about the document?
4. Do you have any comments you want to make about the workshop - organization, space, time allowed, cost, other stuff?