Xerolithography on Clay
Intro
Lithography is a printing process that makes use of the mutual repulsion of oil and water (since water is polar and oil is non-polar). Traditionally, it involves drawing with a hydrophobic (water repellent) oil-based medium on a limestone plate (hence the Greek prefix “litho-,” meaning “stone”). The stone plate is then treated with gum arabic and water to make the surface hydrophilic (water-attracting) and moist. An oil-based ink is then applied to the stone -- the ink sticks to the drawing, and repels from the moist areas.
Our modern laser printers and photocopiers employ a process called “Xerography” that involves a plastic-based, powdered toner, fused to the paper with heat (no liquid chemicals, hence its name deriving from the Greek “xero,” meaning “dry).
Plastic, like oil, is non-polar, and hydrophobic, meaning it will attract oil-based ink and repel water. We can make the paper even more hydrophilic by saturating it with gum arabic, and use it to replicate the lithographic process. Thus, we have xerolithography!
Employing this process to transfer printed images onto clay is simple and fun (but can be a bit finicky due to the polar nature of certain ceramic materials). I have outlined the process and added my notes, troubleshooting and observations.This is a living document, and I will update it as my students and I explore the process together. If you make any interesting discoveries, I would love to know about them! Feel free to add comments to this document.
I am happy to answer your questions, but please make sure you have read and understood the entire document first, and tried researching and finding the answer yourself before e-mailing me at [email protected].
Materials
Laserjet/ Xerox copies of your desired images
Ceramic Stain/oxide of choice
Boiled Linseed Oil
Stainless Steel or Glass Surface
Gum Arabic
250ml Water + 1 tsp Gum arabic (approximate)
Brayer
Spoon
Sponge
Paper Towels
Gloves
Clay + Tools to build your piece
Ink Preparation
Mix around 1:2 stain and oil thoroughly for several minutes. The ink should be the consistency of runny acrylic paint and should not be so wet that your brayer slides around, but not so thick that it absorbs into your paper and goes matte. Sometimes it helps to let the ink sit for 1-3 days, but not so long that it dries out.
Image Printing Guidelines
Images should be clear, high contrast, black and white, with little grey area.
Text should be reversed.
Illustrations (manga, graphic art) work really well and can be coloured in with underglaze when dry.
Tip: put your images into a word document to resize, change to grayscale, flip text horizontally, and change the contrast and brightness. I recommend 40% contrast 10% brightness.
Print LASERJET OR XEROX copies of your images. Inkjet will not work! If you do not have access to a laserjet printer/xerox copier, check your local library or print shop, or ask your friends.
I reckon that the darker and thicker the ink goes on from your printer, the better the outcome on your clay as well, but I don’t know for sure!
Process (Simplified for Quick Reference)
Prepare your workspace: Cover your table and wear gloves.
Prepare your transfer surface: Prep a leather-hard hand-built, wheel-thrown, or slipcast piece, or a slab.
Prepare the wash solution: Mix about 1 tsp gum arabic into 250 ml water.
Attach and saturate the image: Drip a bit of gum arabic onto the steel surface and spread. Place the image face up, blotting excess gum arabic off the steel and onto the paper.
Ink the image: Load the brayer and roll ink over the image in one direction only until evenly coated.
Lift the light areas: Splash a few drops of the wash solution onto the image. Gently dab with a sponge to remove ink from the lighter areas. Repeat 1-2 more times.
Transfer to clay: Clean excess ink from the edges. Lift the image carefully and place it ink-side down on the clay.
Burnish the transfer: Remove gloves and rub paper firmly with the back of a spoon, supporting walls from the inside if necessary. Peel back one corner. If needed, replace and burnish more.
Remove the paper: Peel it off once satisfied, or leave it to burn away during bisque firing.
Dry slowly: Let the piece dry for at least one week before firing for the best pigment absorption.
Process (Detailed with Troubleshooting)
Prepare your work area with a tablecloth and put on your gloves. You may wish to stick your tablecloth and surface down with some tape so they don’t move.
You can print directly onto your hand-build, wheel thrown, or slipcast ceramic object at the leather hard stage (I haven’t tried it on bone dry or bisqueware), or print onto a slab, then build from there.
Prepare a bowl containing around 250ml water and 1 tsp gum arabic and mix. This is approximate, so you don’t need to measure, but having too little gum arabic in the water can cause the ink to not lift off properly.
Apply a bit of gum Arabic to your surface and spread it around. Stick your printout to the surface using the gum Arabic. Dab the excess from the sides over the image using a paper towel or a clean sponge. Clean off any excess from around the sides of the image so it doesn’t get on your roller and mess up the ink application. The goal here seems to be too slightly saturate the paper with the gum arabic so it acts as a resist for the oil-based ink.
On your surface, pour out a bit of your ink and load it on to your brayer. The brayer should roll smoothly back and forth. If the brayer seems stuck in one position, your ink may be too thin.
Spread ink evenly over your image, rolling in one direction only. Avoid rolling back and forth -- your paper might get stuck to the roller. Ink should roll easily onto the image and stay shiny. If the ink starts to dry and become matte, your ink might be too thick or you might be overdoing the rolling.
Splash a few drops of water onto your paper and watch the ink pull away from the light areas and create tiny, pigmented beading on the dark areas (hard to see if you’re using black ink, but you can check a clean image and compare -- do you see the layer of pigment over the laserjet ink?). Dab your sponge around the image until most of the ink has been cleared from the lighter areas.
Using too much water can cause your paper to slide around and become too soggy. It can also interfere with your print when you put it on clay and create big splotches. Not enough water, and your ink will not lift off the light areas properly.
Repeat the rolling and dabbing 1 or 2 more times. It is possible to overdo it, so if it hasn’t worked after the first few times, you need to troubleshoot and/or start over or your paper will just be a mess.
Clean off excess ink from around the image. Lift it off by the corner using a pin tool or tweezers and place it onto your clay, ink side down. Remove your gloves and use the back of a spoon the burnish the print onto the clay. Make sure to support the wall of the piece from the inside if you are doing this directly onto an object.
Carefully peel one corner of the paper to check if the transfer is working. If not, put it back and burnish further.
Once you are satisfied, remove the paper from the clay. You could also keep it on and just allow it to burn off in the bisque firing (but some paper might remain, in which case use a soft brush or blow on it to remove).
I recommend drying the piece slowly over the course of at least a week to give the pigment time to seep into the clay. If you find the pigment is very dusty and rubs off easily after bisque firing, this may be a good solution.
