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HOME GROWN CARBON
TISSUE Here's yet another approach to making your own carbon tissue. I'm not going to deal with formulations of the gelatin matrix. This is strictly about the mechanics of getting it onto the paper. Magnetic sign material is available (*1) into which it is easy to cut a window the size of the patch of gelatin you want to lay down. It is approximately .032 inches in thickness. You will need a sheet of iron for it to stick to(*2) which must be placed on a perfectly level surface. First you soak the paper you are going to use for however long you have done it before. I use bristol two ply paper and soak it in hot water until I can easily peel the plies apart. This leaves you with 2 very thin sheets, each of which has one side with a nice gelatin coating for your pigment glop to adhere to. Squeegee the paper on to your iron sheet with the gelatin side up. Don't bother squeegeeing the back beforehand as it will stick better to the iron sheet under the pressure of the top being laid flat. Now lay the magnetic mask over it. The magnetic material will stick to the iron through the thickness of the paper hard enough to keep the gelatin from sneaking underneath. I'm not sure how that will work with thicker paper as I have always used the bristol. I make my tissue 10x12 on a little larger piece of paper than that. 10x12x.032 comes out about 63 ml but I use 75ml to allow for glop slop. Next you heat up your glop till it is around 120 degrees. I use a plastic grease separator that pours from the bottom to minimize the bubble problem. Pour the glop into the corners of the top side first then let it all flow in, distributing it along the top of the sheet as you go. The next trick is to use a round iron rod as a squeegee to move the glop down the paper. Mine is 1 1/4 in diameter and about 16 in long, mostly because that's what I had, but it turns out to be a good choice. By being that size there is no tendency for it to vary from the .032 clearance provided by the mask. I also preheat the bar up to about 130 degrees so that it will keep the top surface of the gelatin melted in case it wants to gel quickly. With practice, you should be able to distribute it nicely with one up, and one down passage of the rod. The hot rod, (did I say that?) enables you to go as slowly as you need to in order to keep the gelatin from wanting to pile up and go over the sides. It also has the advantage of getting rid of another problem - bubbles. If you do it right, the surface of the glop will be as smooth as glass when you are done. I am fortunate enough to have an old proof press with a 400 pound iron top. This is a great heat sink, so that the gelatin sets rather quickly for as many sheets as I want to pour. The nearer you can come to that configuration, probably the better off you are. When it has set, slice the edges with a toothpick and peel off the mask. Dry it any way you are comfortable with. Some observations: I heat up my glop in a microwave oven. Then I reheat it again between pours. That works for me but I suspect some kind of tempering bath would be preferable. Even though you have to observe the .032 in dimension dictated by the mask thickness, you should be able to control the final thickness of the coating by varying the concentration of the glop. Clearly you can't exceed that dimension without re-inventing the technique. You have to be pretty judicious about cleaning the iron sheet afterwards, it WILL rust at the least excuse, even during the course of using it. I never had that problem with my press so I never fixed it. Be careful to wash the mask between pours, especially when it comes to melting off all the overflow gelatin. Little bits of hardened gelatin can screw things up in a hurry. The reason I am writing this is that
as soon as Sullivan gets his tissue on line, I'm never going to
do this again, and I thought I'd better record it before I forgot
it. Maybe it will come in handy for someone out there. |
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