This past fall, Susan began working on a project for a kitchen backsplash. After the watercolor sketch was completed, the next step was to find a clay technique to capture the colors and feeling of the watercolor sketch while still maintaining the accuracy of the drawing. After consideration, Susan thought the quenca method might work well. Quenca is a Spanish term that refers to the “raised clay line” that will separate one glaze from another within the work. It’s commonly called “tube-lining” here in the US and is often used by artists doing handmade tile.
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The  image above shows the original watercolor sketch and  above that, a raw white clay test tile  which has been darkened on the raised-line pattern. The lines were darkened by gently rolling black/brown iron oxide across the surface of the leather-hard tile with a small spongy paint roller. This tile was later bisque fired in order to harden it and make it ready to receive mid-range temp glazes.
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Making the clay slab: To make the test tile, Susan rolled out a slab of clay (Columbine Cone 6) using her slab roller. She placed the slab onto a piece of drywall board and covered it with plastic (both sides) while she prepared trailing slip.
 
Making the Trailing Slip: Susan set out to make a slip that would create a strong raised line on her tiles and not just slump into the tile surface when heated in the firing. To begin, she gathered bone dry clay scraps (using her Columbine clay) and crushed them into a fine state and added a limited amount of water, letting the mixture set for several days in a bucket with a lid secured. She then mixed it with an electric mixer to fully blend the water and clay and added a few drops of Darvan #7 to deflocculate (adjust the clay particles and make the mixture appear thinner).  Before using the slip, she ran it through a fine mesh sieve to remove any lumps that might otherwise clog her bulb syringe.
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Tracing the design onto the leather-hard clay slab surface and cutting out the tile: Using her photocopier, Susan made a copy of her original design (line work) and used push pins to secure the copy to the clay slab (one push pin in each corner). She then used a regular, sharpened pencil to gently transfer the line-work to the clay surface. After removing the push pins and paper, she cut out the tile from the slab using a needle tool and a ruler.
 
Applying the Trailing Slip to the Tile: A bulb syringe with a larger sized tip was used to carefully squeeze-out the thickened slip over the traced lines on the cut-out tile. The small pins are used to keep the applicator free from clogging up with slip.