cyanotype toning bleach
the basics « MP Photography:
Toning a cyanotype involves two basic steps: a bleach phase, and a toning phase. Every toner I know of contains some type of tannin in it: tannin chemically binds to the iron in the emulsion and changes the color. If I understand this process correctly, it produces a form of gallic acid – used in dyes and inks, especially medieval ones. I’ve read that gallic acid is normally corrosive, but I’ve never found this to be the case with toned cyanotypes.
If you’re concerned about the archival quality of your toned cyanotypes, Dr. Mike Ware (inventor of the ”New” cyanotype process) has said that his family photo albums contain what he’s pretty certain are toned cyanotypes – because they look very similar to other alternative processes it’s easy to confuse with Van Dyke prints or Kallitype prints. I’ve personally never had issues with mine – I’ll get back to you in some 20 years or so and see if that’s still the case.
Keep in mind that toners are funny things – you can mix and match things, you can vary the sequence of bleach and toner and get different results. I have a lot of good results with simply leaving the prints in the toner for long periods of time without bleaching at all. Take things one at a time – don’t try to tone or bleach multiple prints together. Experiment and have fun with it! Just remember that the key to a successful toned print is to wash well between steps.
1. Toning Preparations:
Before you start your toning, always:
- Age your prints at least 24 hours for the emulsion to harden.
- Pre-wet your prints in filtered water to allow the solutions to penetrate the paper fibers evenly.
- It’s a good idea to have multiple prints – toning is fickle, you never know what you’re going to get.
- Plan to leave the print face down for long periods of toning, or plan enough time to “babysit” the print – agitate it while face up in the toner.
2. The Bleach Phase:
Bleaching is a tricky thing. The purpose of bleaching is to help break down the iron a little so that the tannin in the toner can “grab on” easily. If your water is heavily chlorinated, you may not even need to bleach your prints.
How much you bleach really depends on how you coat, how much emulsion is on the paper, and what toner you’re using. If you bleach too far, you lose shadow density. If you bleach too little, your shadows will stay a stubborn blue shade while your highlights cooperate.
Bleach types: the most common form of bleach solution is Sodium Carbonate. That’s Washing Soda, usually found in your grocery store’s cleaner aisle, or at a photography chemical supply store. Don’t confuse this with Sodium Bicarbonate – baking soda – it won’t react the same way.
Other types of bleach that I’ve used are Ammonia and regular chlorine bleach. Ammonia stinks, horribly, and usually produces a browner image. Chlorinated bleach destroys paper fibers and is better left to your laundry.
My typical bleach solution is about 1-2 teaspoons of Sodium Carbonate combined with 1 Liter of water. If your print turns a bright purple the second you place it in the solution, it’s too strong. Play with the solution until you’re comfortable with the rate of bleaching. As you practice bleaching, you’ll notice that it’s a good idea to yank the print out a few seconds before you think it’s ready – the print will continue to bleach a bit while starting to rinse.
Always rinse the print well in running water between the bleach phase and the toning phase.
3. The Toning Phase:
All cyanotype toners are pretty much variations on a black/brown/purple theme. Certain toners are more efficient and stain less, while other toners produce a wider range of possible colors. Keep in mind that all toners will stain your paper base a little despite your best efforts. (please note that the following links lead to blog post about the toners, or examples of the toner shade.)
Tea toner: Most tea toners that I use are brewed for about 10 minutes in 25o mL of hot water, then added to a 1.5 Liter of room temperature filtered water. I use about 8-10 small tea bags, not a very accurate measurement! Every type of tea has a different quality or color to it – make sure that you use teas with tannin in them like black tea or green tea – white tea, red tea, and most herbal teas don’t have enough tannin to do anything to your print.
Green tea produces an eggplant/black shadow, and is so mild that it doesn’t stain the paper base too badly. If you’re toning a high key image, green tea will sometimes produce a really cool pink highlight. It has a tendency to split tone for me because of my double coat of emulsion.
Black tea will stain your paper the most, but it produces a lovely warm black/brown shade that’s nearly impossible to get anywhere else. I generally use a Lipton tea product for iced tea, but any black tea will work. If you want an easy split toner with warm highlights and blue shadows, black tea is the fastest way to get it.
Earl Grey tea: avoid this one – it has a lot of oils in it that can damage your print.
Tea toners work really well with a minimum of bleaching, but they do require a longer immersion for the iron to shift. I normally tone prints in tea for about 2 hours, but depending on the print, it’s taken up to 8 hours. Some people suggest that tea toners should be hot for a faster toner – in my experience that shaves about 30 minutes off the toning time, and stains the paper much worse. It’s a good idea to let the print sit in clean filtered water for about 10 minutes before the final rinse to help remove some of the excess tannin. All tea toners should be used freshly brewed – they lose potency after a day and should not be reused.
Tannic Acid Toner: This stuff is a royal pain to work with. It can produce the closest thing to a true black, but it’s far more likely to screw up, or produce a weird purply brown shade. It has the widest range of color tones that I’ve seen in a toner, but you have absolutely no control over what you get. Be extremely careful how much bleaching you do, because this toner is totally unforgiving if you go the slightest bit too far.
Done well, this toner produces the least paper staining – however, I’ve run into some chemical issues that I don’t quite understand that leave my paper the shade of cardboard. (I’ve narrowed it down to interactions with the tap water, or the age of the toner.)
Tannic Acid is produced from wood chips, and is extremely hard to mix into a solution. It’s a gummy mess. Because of this it’s difficult to estimate how much I use, but generally about a Tablespoon mixed into a Liter of water is a good place to start (and then remove the gummy bits.) A good tannic acid solution should be almost clear, and will take a minute of sitting in filtered water to fully tone out. Toning times for tannic acid are usually quite short.
If mixed with distilled water, tannic acid toner will last for a few weeks/months. A little mold is normal, just filter the solution every time you use it. Once the solution starts turning a dark brown or granulating (tiny little granules appear – not sure what they are) it’s time to start fresh. Tannic acid is also quite expensive, and only available at a photography chemical supply store like Photographer’s Formulary.
Coffea Toner: I love coffee toner. It’s a cold toner, as opposed to the warmer tea shades, and it leaves the paper pretty close to the original color. It will still stain, just not as badly as tea. Coffee doesn’t produce a true black, but more of a blue/black like a blackbird’s feathers. The highlights will stay pretty clean so make sure your contrast is good and your highlights aren’t blown out.
I generally use the cheapest instant coffee I can find – about 4-5 heaping tablespoons of instant coffee dissolved into 250 mL of hot water, then added to 1.5 Liters filtered room temperature water. I’ve read that other people have great success re-brewing used coffee grounds – since I don’t drink coffee I can’t exactly test this.
Coffee toner doesn’t seem to take quite as long as tea toner, but expect at least an hour of toning, perhaps more. Again, it’s a good idea to let the print rest in a water bath before the final rinse.
Wine Tannin: This is my new favorite toner, and I don’t have that much experience with it yet. So far, it produces a nice dark shadow and a brown/tan highlight on a fairly regular basis. It can be rather fickle if you keep the solution for a long period of time, so I suggest storing this toner no more than a month.
Wine tannin is basically the same thing as tannic acid, but produced from a different source. It’s designed to use in microbrewing so it mixes into solution a lot easier. It leaves the paper almost paper white, producing almost no staining. It’s slightly cheaper than tannic acid, but since it requires more to produce the same effect – half an ounce of wine tannin mixed into 1 L of water – the price is probably pretty close. I use the powdered version, but some stores have a liquid solution available.
Wine tannin has a tendency to put any coating discrepancies on display. Unless I use the Christopher James variation listed in the link (toss the print into the tannin instead of bleaching first) I lose some of my highlight detail. Like the tannic acid, it works pretty quickly. Wine tannin also has a weird chemical reaction that can turn my paper to a cardboard brown, requiring a water bath before the final rinse.
1. My print looks faded! What happened? You probably bleached the print too far. Try test strips in varying times to get a better idea of what works – the ideal is to tone your shadows dark without losing highlight details. Usually this means bleaching until the shadows are a dark purple and the highlights are slightly yellow.
2. I left the print in the toner forever, but it’s still blue! What now? Rinse the print for at least 5 minutes and go back to the bleach bath. After bleaching again – just a little, rinse it again for 5 minutes and put it back in the toner. Your initial bleach probably didn’t break the iron down enough.
3. The print toned nicely, but now that it’s dry I hate it! Why does it look so flat? I don’t know why, but that’s normal for a toned cyanotype. Try brushing a diluted solution of acrylic gloss medium onto the print to bring back the shadow depth and give the surface a little shine. It will look like it did when the print was wet.
4. Why can’t I produce the same results each time? What am I doing wrong? Nothing. That’s a quirk of toning. If you have a batch of prints that need to look similar, try toning them all at the same time with the same solution. Otherwise you run the risk of variations that you may or may not like. If you’re still having issues, stick with the basic tea toner – it’s a little less fickle.
5. My print looks mottled – it didn’t tone evenly. What’s going on? If you’re leaving the print in the toner for a long period of time, make sure you place it face down. Paper floats oddly, and you may end up with “dry” spots that don’t tone evenly. If you’re toning face up, make sure you agitate the print constantly.
6. My print has a bright blue round spot on it! Yup, the curse of the air bubble strikes again. Make sure the print is lying face down – ease the print into the toner slowly and work all the air bubbles out past the far edge. If you already have the blue spot on it, try a quick rinse, bleach bath, and return the print to the toner for a bit to remove the blue.
7. My shadows are blah. What happened to my perfect exposure? Your original shadows need to be a nice, deep, cobalt blue to tone dark. If your shade of cyanotype isn’t dark enough, it’s not going to tone well. Read this tutorial and do some experimenting with your paper and your developer first before you try toning again.