In the Studio: Plaster Transfer Forrest Lesch-Middelton

Appears in the Sept/Oct 2020 issue of Pottery Making Illustrated.

Plaster transfer is a unique method of applying an image with fine detail onto a clay slab or tile with underglazes. Plaster transfers can be done by screen printing or painting an image (monoprinting) directly onto cast plaster. I use the screen-printing method, but you could do the same by painting underglaze directly on the plaster as a monoprint transfer.

Tools and Materials

• Plaster slab: 18 × 20 inch (45.5 × 51 cm), flat and smooth
• Custom pre-printed silkscreen
• 70-durometer squeegee
• Underglaze
• Casting slip: 1 pint (475 ml)
• Leather-hard tiles: 4 inch square (10.2 cm) (optional)
• Wooden knife tool
• Clay: 5 pounds (2.3 kg)
• Tile cutter, pizza cutter, or fettling knife

This process shares some elements with newsprint slip-transfer techniques, but instead of applying your transfer medium (underglaze or slip) to newsprint, you will print or paint your image directly onto a clean and smooth plaster slab.

Silk-Screen Printing

Lay your pre-printed silkscreen directly on the plaster slab (1), run a band of underglaze across the top of the screen, and use the squeegee to apply a single layer of underglaze through the screen onto the plaster (2). Because plaster is absorbent like a sponge, make sure to lift the screen off the plaster soon after printing or it may stick and clog the screen (3).

Casting and Transferring the Image

After the image is printed on the plaster slab, use clay coils or cottle boards to build a ½-inch-high (about 1 cm) dam around the image to act as a reservoir. Once in place, shore up the bottom edges of the reservoir with a final clay coil sealed tightly between the reservoir and cottle boards all the way around to prevent it from leaking (4).

There are two pouring options for making a transferred tile or slab. The first is to pour the slip to the thickness that you would like for your tile or slab (5), and then let it sit for about 30 to 60 minutes, until the slip has set and feels firm enough to release from the plaster slab. Remove the dam and begin to gently peel up the edges of the clay slab to test whether it will come off easily. If it feels loose from the plaster slab, peel up the clay completely and reveal the transferred image.

Place the clay slab image side up on a flat table (6), and cut out the size of tile you’d like with a tile cutter, pizza cutter, or fettling knife.

The second option is to create a thin veneer that will be laminated on top of the tile. You will need a leather-hard tile that has a compatible shrinkage and firing rate to your slip. Pour the slip on top of the plaster slab to no more than 1 to 2 millimeters thickness. While the slip is still wet, place the leather-hard tile (or tiles) on the wet slip. Let the tile sit for 30–60 minutes, until the veneer has stuck to the tile and they both begin to release from the plaster slab together as one piece. Carefully cut around the tile and through the slip veneer with the wooden knife, making sure not to damage the plaster slab. By now the tile should be ready to lift up with the slip veneer adhered and be turned over, revealing a cleanly laminated image on top of the tile. Let the two sit and dry slowly to make sure that the veneer doesn’t pull away from the tile.

Excerpted from Handmade Tile: Design, Create, and Install Custom Tiles by Forrest Lesch-Middelton, published by Voyageur Press, an imprint of The Quarto Group. To learn more, visit https://quartokno.ws/HandmadeTileand to purchase, visit https://ceramicartsnetwork.org/shop/handmade-tile. See more of Forrest’s work at www.flmceramics.com.