Monday, July 6, 2009

Day 1: Plate prep and some extras.

Plate Prep: Ball-Grained Aluminum

-Plates should be handled carefully to prevent kinks or ripples, and care should be taken not to touch the drawing surface, as oil from your fingertips can affect the image.

Unless you have a plate shear, you'll need to cut the plate with a utility knife. Place grained side down on newsprint, mark the line along which you wish to cut, clamp a straightedge to the plate and table to keep everything 
secure. Score along straight edge several times, before snapping across ruler or table edge. Be sure to score enough, or plate can pinch and kink along the edge. Round the corners ever so slightly with scissors to protect your hands during printing. Shave or file off any burr to protect the slate, tympan and your hands. 

Hot Water- for most purposes, cleaning with hot water is sufficient. Cover plate with hot water and rub down very gently with a shop towel or cotton pad until towel comes up nearly clean. Be sure to overlap strokes to prevent streaking, and dry immediately. If you want to be absolutely sure the plate is cleaned, wet plate again (not too much, or it will dilute the acid), pour a little plate counter etch (water, hydrochloric acid and phosphoric acid) and wipe down in the same manner as hot water. Dry immediately. Don't let any spots of water sit on the plate. This can be done as many times as you like, although some people think doing it multiple times will wear out the grain of the plate. In any case, your plate should be plenty clean by now, and processing solvents will take care of anything you missed. Store your clean plate in newsprint to minimize oxidation.

Preparing the plate for drawing: Layout and format considerations
Paper size is very important. You should leave a small space between the edge of the plate and the edge of the paper. It's a good idea to choose your paper ahead of time, and run it through the press so you can see exactly how much it will stretch under the pressure. This assures you that you have an exact measurement for the final print. A mylar or paper jig can be made to finalize the layout before any marks are made on the plate. After a jig is made, mark the plate the way you would like (image edge, paper edge, center points and any other guidelines you need) in conte' crayon or very hard pencil. (use of any material containing grease WILL print, so for sketching, stick to conte') 

A little digression: Tusche 
Tusche is a greasy material that behaves a bit like watercolor. It is either water or solvent soluble and is painted on with a brush or applied with quill pen or other instruments. It is a popular drawing material for the ethereal quality of the mark when the water evaporates from the mixture. A test sheet for tusche can be made by first creating a concentrate (this example uses Charbonnel stick tusche). Rub a stick of tusche all around a small old plate until it's black. Pour about 20ml of distilled water and mix with a medium bristle brush until a slightly syrupy consistency is reached and all the tusche is dissolved in the water. Pour about 15ml of distilled water (make sure the pH is between 5.0 and 7.0) into each of three beakers. Visually with the brush, or more methodically with an eyedropper, mix three solutions, light, medium, and dark, one in each beaker. Test by painting onto a sheet of white paper until the solutions look right (that is they have the proper variance between light medium and dark- use a grayscale if you are unsure). These solutions can now be used for drawing on an aluminum plate, and can be stored by putting a piece of packing tape over the mouth of the beaker when not in use. 


These are my original notes from the 2009 Tamarind Aluminum Plate Summer Class, where I'm volunteering as a press assistant. If you have a need, feel free to use these notes. I won't vouch for their accuracy since  I wouldn't presume to know nearly anything about lithography compared to the people at Tamarind, though I do take pretty detailed notes. You should obviously only be doing this is a properly equipped studio with ventilation and adequate tools and supplies. For some serious notes, instructions and formulas, get the book. Or buy it for me in gratitude for providing my notes. :)

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