Also known as ferrotypes. Ken Watson gives us the details and how-to.
Always be careful when handling chemicals. Read the health and safety instructions.
This “recipe” is written in 3 sections:
- Ken’s recipe for collodion, which is what you have to start making
- A Question and Answer on the process
- A step-by-step description on how to make an image
1. The collodion recipe
- Ethyl Alcohol 95 -100% pure. Actually 95% is preferred otherwise you will need to add water.
- Ethyl Ether
- Cadmium Iodide
- Cadmium Bromide
- Non flexible collodion OR Nitrocellulose. Nitrocellulose comes at differing nitrated levels. You are looking for stuff to finish furniture with NOT the stuff used for making gunpowder.
- Distilled water
- Acetic, but I would suggest Sulfuric acid
- Silver nitrate.
- Ferrous sulfate
Ken’s collodion formula of Salted collodion
- Cadmium Iodide: 2.55 gr
- Bromide: 1.54 gr
Dissolve the two above with 4 drops of water.
- Collodion (non flexible): 118 ml
- Ethyl ether: 77 ml
- Ethyl alcohol: 77 ml
Dissolve the bromide and iodide in a small test tube. Use your hand to keep the water warm while using a glass rod to stirr and crush small chunks.
Once dissolved, pour into the base collodion.
Combine ( pour ) the ether into the base collodion mixture.
Use the alcohol to rinse the test tube and glass rod by adding some to the test tube and stirring. When you are satisfied most of the bromide and iodide are out of the test tube pour the remaining alcohol into the base collodion. Small spills are ok.
The collodion is now complete and should look water clear. After a few days a yellow blush will develop. After months or years this will deepen into an amber.
It is now the salted collodion that gets poured onto glass plates or japanned iron / tin.
2. Question and Answer on the process
A piece of glass is thoroughly cleaned and polished. For ferrotypes, japanned iron is needed?
Glass that is clean of any contaminate and dust is what you are looking for. Polished maybe more than required. I use a weak hot detergent solution and several clear rinses in hot water. I usually clean 50 or so plates at a time. I dry them as I work and stack the 10 to 15 to a sheet of aluminum foil. The foil just keeps dust off and does not add contamination. Plastic wrap leaves a film, but it does no seem to bother the collodion much. Works better than what I hear about otherwise, like rottenstone and alcohol.
Holding the plate by the fingertips in a horizontal position, the collodion is flowed over the surface to form a smooth, even coating?
Yes, there are basically two techniques. One is to pour the “correct” amount of collodion into the center of the plate and rock it so that the collodion moves into the corners. The second is to start in a corner and pour constantly while rock / adjusting the plate to move the collodion into the first two corners, about half way through covering the plate you can stop pouring and guide the collodion into the last two corners and then the excess is drained off. I drain mine right back into the pour bottle, others do it differently. By 8 X 10 size you can not hold the glass by the finger tips. I actually use a metal spring clamp (rubber tipped) that is common in hardware stores to hold the glass. It allows a nicer, more relaxed wrist attitude that allows for better control. I actually grip the clamp as I pour. It also keeps collodion from running down my hand and arm if I make a mistake (something you will do a lot early on).
In the darkroom, the coated plate is quickly put into a bath of silver nitrate solution and allowed to soak for several minutes. It is withdrawn from the bath (now light sensitive) and while still wet put into a light-proof plate holder?
Yes, but the plate is allowed to drip dry after the bath for may be 20 seconds and then the excess silver bath is wiped off the back. Note: it is only sensitive to blue and UV light. Very very bright red light can be used to see what you are doing. Much brighter than any modern B & W photographer would believe.
The plate holder is taken to the already-focused camera. The dark slide is removed and the exposure, generally about five seconds long, is made by removing the lens cap. The dark slide is replaced and the holder (containing the plate) is returned to the darkroom for processing?
I expose at F8 for three seconds. Most people can hold still that long and the exposure is long enough so that if I am 1/2 second off it is not a big deal.
In the darkroom, the plate is removed from it’s holder and developed by pouring an acidic iron sulfate solution over its surface. When the plate is judged to be fully developed, it is rinsed in clean water?
Not exactly true. To be successful wet plate is a development driven process. That is tot say you adjust everything so that you have the exact picture (ambrotype) you want in 15 seconds. This is very important in the beginning so that you do not do things that make sense with respect to modern photography. You will just get frustrated. The 15 second rule should be a hard and fast rule until you have successfully completed about 100 plates. Of course many develop longer , but for the best images 15 seconds is it. The advantage to wet plate is that development is can be done by inspection. It takes quite a number of plates and mistakes to be able to watch an image come up and know when to stop development by looking for shadow details.
The plate is put into a solution of hyposulphite of soda or potassium cyanide to dissolve the remaining unaltered silver salts. It is then washed thoroughly in clean water?
Yes, while you fix, watch how long it takes to clear, then let it rest for that length of time again. Unless you cyanide, then it is clear when it is clear.
Over a gentle flame the fixed plate is dried and usually hand colored, then you varnished to protect the surface?
Here is where I depart from a lot of people. I do not varnish. I have been looking for a modern coating that is optically clear and a lot less hassle than keeping my varnish at 100 degrees F and getting the plate to that temp and HOPE that I do nothing to screw things up as I try to cover the plate.
If you are making ambrotypes, I usually use a black acrylic paint that I get from Wal Mart or a hobby store. I paint onto the collodion with flat black. Great background and it protects the collodion.
So I dissolve with 4 drops H2O the Cadmium Iodide and bromide which I add to the collodion, ether and alcohol?
The heat from your hand and glass rod will most likely be enough to get this into solution. May also need a dropper.
That would make me a 300 ml Salted Collodion mixture?
Yes. I would add the additional alcohol and ether after adding the iodides and bromides to the collodion. Use some of the alcohol to help rinse out the container you used to mix the bromides and iodides.
Also you mention that instead of collodion I can use Nitrocellulose. Correct?
Yes, but it will need to be dissolved into an ether and alcohol solution.
Nitrocellulose will most likely come packed so that it is wet with alcohol. This is to help prevent electrostatic sparks that would cause the material to burn rapidly. It is important to handle this stuff carefully whither in solid form or in solution. The most dangerous thing about collodion is the ether. It boils at very low temperature , it is heavier than air. So if there is a leak it fills up a container, like a room or house up to the point of an ignition source. If ignited like this it is a big explosion. So keep the lids on tight and stuff well ventilated. Also, ether will put you to sleep in a hurry. So when you add it to the collodion do it outside. I initially tried a funnel to help add it to my collodion in a bottle. I was carefully watching it go into the bottle while slowly pouring it into the funnel. It stopped going in so I stopped pouring. I lifted the funnel and a LARGE quantity of ether flooded my hand an pants. It was liquid locked around the funnel and being so light I did not realize there was ether in the funnel. As I was thinking about what had just happened and that it was time to get to fresh air I was becoming light headed so I held my breath and rapidly got out of the area.
Equipment: Is what I listed below enough or did I forget anything?
Small test tube for mixing the iodides / bromides and water. I would not use the graduate for this.
Silver bath. Mine is made from acrylic which I used gaffers tape (opaque) to wrap in order to make sure no light could get in. You can not use wood as the silver will react with it. You do not just drain the plate in the bath you also sensitize the plate in the bath once poured.
Gloves: Get latex disposable type. you will need more than one pair. They usually come in packages of 50 or 100 for about $10 US I think , maybe less. Get them without powder. Latex, vinyl, and nitril are common material and all work OK.
If you can find sheet glass, glass cutter and a T square it would be a good idea to learn how to cut glass. It is not really hard and you can buy glass in common sizes and cut it your self.
3. Step-by-step description on how to make an image
1You need a process that starts in one spot and goes forward with out dragging any chemistry back to the start. That way you will always have clean chemistry and no cross contamination.
I use one paper towel per image and one set of gloves per image.
I start with the clean glass, paper towel in hand and gloves on.
I retrieve a sheet of glass and examine it to determine that it is clean. If there is a speck use the paper towel to remove it.
2I clamp the glass into the spring clip and hold it with my left hand.
I place the towel down to rest in a clean area.
I uncap my pouring bottle with my thumb and fore finger and set the cap down in a clean location. The tip that is usually inside the bottle is oriented up so it does not pick up contaminants.
I pour with my right hand, guide the plate with my left. When I think I have enough collodion onto the glass I move the pour bottle into place to catch the drain off of the plate and maneuver the collodion to the corner so that it can be drained off.
Once the drain off is complete I recap the collodion, take the lid off the silver bath and drop the plate into it. Then place the lid back on the bath.
3Wait two minutes, make sure there are no light leaks (in the field) and remove the plate.
Grab it with both hand and shake it down into the bath to remove excess solution. By now you can see that has changed from clear to cloudy. In daylight it looks pale yellow.
4I grab the paper towel and wipe the back dry and place the plate face down into the plate holder. Note: most collodion back are loaded from the rear. I place the towel down, check to make sure the lid is on the silver bath, the dark slide is closed and the back is locked shut on the plate holder. Then out into the light.
5Load the camera, make the exposure then back to the dark room.
Place the holder in front of me as I loaded it.
Make sure there are no light leaks.
6Get out the developing tray. Open and pour the correct amount of developer into a shot glass. About 15 ml for a 3 1/2 X 5 inch plate if memory serves.
Remove the plate and place it into the developing tray collodion side up.
Pour while sweeping the developer across the plate and start counting to 15. Rock the developing tray back and forth and look for dry spots on the plate. Constant agitation until 15 is reached.
Pour off the developer into a container and flood the plate with water to stop development.
7I lift the plate to dilute developer that is trapped between the back.
I then come out of the dark room and rinse the plate by splashing water on the front and back with my hand and then into the fixer. (Once again this is a field expediency).
I have a fixing tray that is vertical, almost, made from plexiglass / acrylic. Customers can watch the plate as it is fixed out and turns from a negative to a positive. EVERYONE enjoys this.
While this is happening I use the used paper towel to wipe the inside of the developing tray to get it clean for the next plate. Then throw the towel away along with my gloves.
8When fixed I then rinse in water for at least 15 min then let the plate dry, then paint.
For a tintype made on blackened tin no painting is required.
Once fixed and then rinsed to remove the fixer ( 15 Min) once dried it is done.
A protective coating should be used. I do not shoot tin types but use black glass. Since I am careful, I do not coat the glass. it is easily scratched.
There is not a negative in making tintypes.
Making tintypes is identical to making ambrotypes. The differences is that one is made on glass, the other on japanned tin.
Photo Imaging – A Complete Visual Guide to Alternative Techniques and Processes
by Jill Enfield
A definite resource for mastering alternative photo-imaging techniques with a great chapter on the tintype process.