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Lesson Info

Coating Process and Cyanotype Chemistry

Okay, so, we got the brushes. I'm gonna show you the coating rod. I'm gonna show you the ink brush. You'll see the synthetic brushes tomorrow. We're gonna go ahead and start to talk about the coating process. I've got my paper down, it's nice and level. I've got it on a smooth surface. This is my ultraviolet light source box. What's in there is a bank of fluorescent tubes that are doing fluorescent light, kind of like a blacklight, but not quite a blacklight. We're in the 320 to 400 nanometer wavelength, medium length ultraviolet light. It's a consistent source of light for us. But because they're fluorescent tubes, I turn that on when the darkroom starts, because I want those tubes to come up to temperature and be consistent. If you ever turn on fluorescent bulbs, they'll kinda flicker, and you'll see them kind of start to light up over time. We want to make sure that that light is consistent and as even as possible, so that gets turned on right away when I come in the darkroom. I the...

n get my paper out, I get it all situated and set up. I'm gonna need a pencil, my coating surface, my brush. And what this is, is distilled water. I'm gonna put the brush into the distilled water 'cause I want the fibers of the brush to get wet, so that it won't suck up and hold all the chemistry. 'Cause those brushes want to pull liquid. We're gonna give it the dampness of the fluid, we're gonna, I'll show you how we get that out, but we want the brush to feel damp, but not wet, but we definitely don't want it to be dry. If it were dry, you'd literally make about two brush passes and the chemistry would be gone and you wouldn't be able to coat the surface of the paper. We're gonna wanna make sure that our brush is in some distilled water. That color is 'cause we were doing some preliminary testing. You'll see that water start to shift color over time. You're gonna need a shot glass or a plastic, a little plastic cup. If you go to a fast food place and they have the little things you can squirt ketchup into, I'm not saying I have a bunch of those from a fast food restaurant, but I have some of those plastic cups that I use which are great. Because if they crack or get contaminated, I can just throw the plastic cup away. But you're gonna need something to put the sensitizing solution in. Now you've got something for the sensitizing solution. You've got your brush, you've got your paper. You're also gonna need your contact frame or a really heavy piece of glass for the image to sit under. We're gonna go on ahead and have the contact frame ready. And then I need my negative. So in this case, I've got this digital negative. And in this one, I put a step wedge in. We're gonna test it and see what it looks like with the step wedge. It's an image from the Jefferson Memorial. I've printed this in other processes, but not a cyanotype, so that's how I chose it. I want to see what this looks like in a cyanotype. I've looked at it in platinum, I've looked at it in Van Dyke, so I thought it'd be kinda cool to see what it would look like as a cyanotype. What I wanna do is, I wanna coat the surface such that I kinda hit just outside the edge of the paper. I don't wanna coat the whole paper. I wanna leave a little bit of the framing there. So I need to know how far to make my brush strokes. What I do is I lay the negative down on the paper, and I think about this somewhat, we'll talk about this a little bit when we talk about matting and presenting tomorrow, but you can see I've got the image just a little bit higher on the piece of paper, than the bottom. That actually creates the optical illusion of it being centered. If it's got a little bit of weight to the bottom, our eye just believes it's gonna be a little bit higher, and I kinda ballpark center of left to right. If I'm doing really anal-retentive work, I actually have a ruler that I lay out and I make sure everything's nice and centered. That is completely pointless because the coating is never that precise. But sometimes I am that anal-retentive. Then what I'm going to do, is take my pencil and I'm just gonna make a little tick mark kind of at the edges of where my coating area is. And this just is at the edge of the negative and it allows me to know where the negative is so that I know where to start and stop the coating process. I don't worry about it being super exact because I'm gonna go outside the lines as I coat. Now I've got my little tick marks where the coating's gonna be. I set my negative aside. I set my pencil aside. Now I'm ready to start thinking about the sensitizing, putting down the sensitizer. Each process has its own type of chemistry, its own set of sensitizers. If we look at the chemistry for cyanotypes, we have two: we have a part A and a part B. It's a ferric ammonium citrate and it's potassium ferrous cyanide, are the two chemicals together that make up a cyanotype solution. What happens is, when the two chemicals mix together, and they're exposed to UV light, the ferric ammonium citrate, green, actually becomes a ferrous metal. So that's what stays as the residual metal in the print that gives us the ultimate look of the cyanotype. It's also the interaction with the potassium cyanide which gives it the blue color. We need those two together to actually create the chemical reaction when it's exposed to ultraviolet light. The cool part about a cyanotype is it's not hyper-sensitive to ultraviolet light, so you can actually coat under pretty normal lighting conditions. A 40 watt, 60 watt tungsten bulb, which is like a normal household bulb, you could easily coat under that with no real impact. Fluorescent bulbs will have a little bit of UV light in them and could cause an impact. For me, I just, because my darkroom's set up for alternative processing most of the time, I just kick on everything into the ultraviolet light mode. What I'm gonna do here is, I'm gonna coat a couple of sheets of paper without the ultraviolet protection lights going on, then we'll put the ultraviolet protection lights on so you can see what those look like and we'll coat from that standpoint. I'll talk a little bit more about the lights. I wanna make sure you can start to see the coating process and how that works. Before I actually coat this one, I'm gonna use this brush as a demo. You're not painting. You're coating. You're not painting. This is not how much can I, if you're painting your apartment, you're in a hurry. You're like mash the paint into the wall. You push the roller as hard as you can. That's not what we're doing. This is a very light, even touch. We don't want the chemistry to get onto the sides of the brush. We want it to stay down on to the tips of the brush. It's mostly an arm movement. It's not wrist motion, it's an arm motion. It takes practice. This is why I love starting people off with a cyanotype process. Because the coating process is the exact same for Van Dyke, it's the exact same for platinum in terms of the motion and how we actually coat. This stuff is really, really cheap. It's really easy to use, super easy to practice with. And so to get that motion down, using the cyanotype is one of the reasons I like to start people off with the process. What you're gonna do is, we're gonna pour that chemistry kind of in the middle of the paper. And then we're gonna take our brush, and we're gonna slowly go back and forth in a very consistent, but very light pattern. Then we're gonna switch and go up and down. You can start to see where those brush strokes would come from, as the brush hits the end and I pick it back up and I come back down. What I'm doing is trying to move the chemistry along so that it'll be absorbed into the paper. Certain papers are more absorbent than other papers. Sometimes it takes a little bit more work. If you've got a paper, like the BFK, the Rives BFK paper, is not as absorbent as some of the other papers at the get go, so one of the things you can do is you can use a chemistry called Tween 20, T-W-E-E-N 20, and it basically acts like almost, it feels almost like a soap and it helps break the surface tension of the paper. If you don't have that, just a little distilled water, and just paint a little distilled water over the area you're gonna coat. It'll break the surface tension of the paper and the chemistry will be easily absorbed. It's a pretty easy problem to solve. Basically, it's just a back and forth. It should take about 30 seconds of back and forth for that chemistry to be absorbed. The key here is not to over-brush, because what happens as you start to over-brush is that surface of the paper is getting softer and you're gonna start pulling the fibers of the paper up, and you end up with this weird molting of the paper and modeling, and the paint chemistry doesn't get laid down evenly. So you wanna try to get nice and smooth, and nice and even. Also, if you realize the middle doesn't look quite right, you don't come back and fix it. Once the chemistry starts to set in, it's gotta just kinda finish its process. 'Cause if you come back in later and put a brush stroke across, you will see that perfect brush stroke across your image. I have a lot of prints where I've got brush strokes across. The other one is I'll sometimes start with a diagonal but I'm always working left to right, top to bottom. I never go back to working diagonals, 'cause the streak marks become more apparent because of the long pull as the paper starts to dry. So you're gonna work left to right, top to bottom, in that process. For a cyanotype, we use parts A and parts B. Part A and Part B are used in equal amounts. If you're gonna process an image, you're gonna use, if you use 10 drops of A, you use 10 drops of B. If you use five drops of A, you use five drops of B. For an eight by 10, about the size of the image we have there, we're gonna need about 40 drops. What we're gonna do is, we're gonna take off the cap to A. We're gonna pull up some drops in the eyedropper. And then we count the drops. I recommend when you start, you count out loud. It's amazing how fast it is to get distracted. We're gonna go one, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, oh, 17, so close, 18, 19, 20. Okay, then once that's done, I'm gonna then 20 drops of B. One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, aw geez, so close again, 18, 19, 20. So that is all the chemistry, it barely even covers the bottom of the shot glass. That's all the chemistry we need to coat that piece of paper. What I'm gonna next do is pull my brush out and then I'm just gonna gently blot it into some paper towel and pull out that excess chemistry, or excess water that's in there. The brush is now damp, but not wet, no water's coming off when I paint my hand. But I can feel the dampness of the brush. The next thing I'm gonna do is, I'm gonna take and pour the sensitizer in the middle of the paper. Tap out the excess and then I start that coating process. I'm gonna go back and forth. I'm not pushing down, I'm literally just letting the fibers of the brush drag across the paper. I make sure I get outside my edge of my line. That's it. Then I'm gonna stop, brush goes back in. Now that page can go sit and get ready to be dried. You usually want to set, for this process, you can let the paper sit for a couple of minutes and then you can hit it with a blow dryer. You're gonna blow dry on low heat from the backside of the paper and that's gonna help pull some of the chemistry into the paper and speed up the drying process. If you do that, you'll want to do that in a well-ventilated area and probably wear a mask because it can kick up some of the particulate off of the paper if it gets bumped or some of it comes off. That's one of the reasons to always dry from the back of the paper. 'Cause then you're pulling the chemistry back in. There are people who blow dry the front to speed it up but that's what causes that iron to kick off and you just wouldn't want to inhale that. Once you've got your chemistry all sensitized, then you definitely want to go back and recap your chemistry. Get that all set up.