Wet slip inlay is a great technique for getting fantastic organic patterning on pots. Basically it consists of layering contrasting colors of slip on a slab and jiggling the slab to distort the slip layers into interesting marbled designs.
In today's post, a sneak peek from the upcoming September 2013 issue of Ceramics Monthly, Robert Strasser shares his techniques and tips for working with wet slip inlay. For the rest of the article, keep your eye out for the September 2013 issue of CM.
When I was in college and just a few years into making ceramics, I took a two week trip in early summer to England. My primary goal was to meet as many potters as I could. The experience deepened my love of English ceramics and introduced me to a technique that has been one of the most exciting veins in my studio work ever since: Wet slip surface inlay.
I had read briefly in Bernard Leach's‚ "A Potter's Book" about slip application and how to get surface marbling and feathering patterns on flatware using slip trailers to decorate thin slabs of clay. There in England, in the studio of his son David Leach, I got to see in person my first finished examples of feathered slipware. On the same trip, I visited the Victoria and Albert Museum and had the opportunity to see a large, and particularly fine, marbled dish with an amber lead glaze made in Staffordshire in the early 1700's. I wanted to reproduce these effects, and so my creative journey making slipware began.
I begin the process with two or more slips of equal viscosity, homogenized through 40-mesh screens. A base white slip can be colored with stains to develop as large a palette as desired. A darker slip provides contrast, making patterns bolder. It is very important to screen the slips immediately prior to use or they tend to settle and flocculate, causing the edges to bleed during and/or flow irregularly after application. Rubber slip applicators are filled with the various colored slips to be used in decoration (conserve resources by starting simple with just two slips, enlarging the color palette once sufficient comfort with the process minimizes material loss).
Cut or roll out clay slabs and put them on cloth scraps for handling. I form slip-decorated slabs over hump molds, so I make them about an inch larger than the edges of the hump molds to be used for making dishes. Place a slab on a ware board and begin by flooding the wet slab with slip, tilting the board to spread it out evenly over the entire surface. The inlay colors can be applied onto this base slip with a steady hand in whatever pattern and combination is desired (1). Straight lines work well for feathering and marbling, while dots in alternating colors create concentric cells that, when tilted, flow into elongated shapes (2). These circles can be manipulated into a pattern that resemble wood grain when stretched by tilting the ware board in opposite directions.
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Once an appealing pattern is achieved, set the slab aside for about a day to allow it to reach leather hard. When the slip surface can be touched lightly without smearing, it's ready to be formed over a bisque or plaster hump mold.
The primary consideration for glazing is to avoid treatments that will mask the slip decoration. I typically use transparent or translucent glazes that show off the patterns underneath, but a very thin application of opaque glaze such as the shino applied to this piece gives the surface additional depth.
Robert Strasser is a ceramic artist and environmental biologist living in the Washington D.C. area.
For more interesting ceramic decorating techniques, download your free copy of Five Great Pottery Decorating Techniques: A How-to Guide for Decorating Ceramics with Slip Transfers, Chinese Brush Techniques, Ceramic Slip, Sgraffito, and More.