For unparalleled textural depth in your ceramic creations, consider layering multiple thin, flattened clay forms, applying contrasting slips between each. This method, often overlooked, introduces unique strata visible upon firing and subsequent carving. Aim for individual sheets no thicker than 6mm to ensure even drying and minimize warping.
Mastering the art of joined panel fabrication pivots on precise mitering of edges. Employ a sharp beveling tool to create 45-degree angles, yielding seamless corners. Reinforce the inside junction with a coil of fresh clay, blended meticulously to eradicate potential weak points. Remember, slow drying under plastic is imperative to prevent stress fractures during the initial stages.
Push the boundaries of conventional formed panel art by incorporating found objects during the assembly process. Embed metallic elements, glass shards, or even organic materials directly into the surface before the clay reaches leather-hard consistency. This not only enhances the visual intrigue but also adds an element of surprise as the piece matures throughout the firing process.
How to Hand-Roll Perfectly Even Clay Sheets
Achieve consistent sheet thickness by using two parallel yardsticks (0.25 inches thick) as guides. Place these yardsticks on either side of your clay mass.
Use a rolling pin with a diameter of at least 3 inches to distribute pressure evenly. Smaller rollers are prone to causing unevenness.
Rotate the clay 90 degrees after each roll to prevent elongation and ensure uniform thickness across the entire surface. This also relieves internal stress.
Dust the work surface and the clay frequently with cornstarch to minimize sticking. Too much water leads to adhesion and distortion.
Apply consistent, downward pressure with each roll. Avoid abrupt changes in pressure, which create thin spots.
Wedging the clay meticulously prior to rolling removes air pockets. Air pockets trapped within cause blisters during firing.
Periodically check the sheet thickness using calipers. Aim for variations no greater than 0.03 inches across the entire sheet.
If the clay sheet becomes too thin in one area, gently lift the thinner sections and add small coils of clay to the underside before re-rolling. This helps maintain uniformity.
Important: Allow the rolled-out sheet to rest, covered with plastic, for at least 30 minutes prior to fabrication. This allows the clay to relax and minimizes warping.
For very large pieces, consider using a canvas cloth beneath the clay. The canvas provides additional support and prevents the sheet from tearing during handling.
Designing Unique Forms with Drape Molds
To achieve intricate draped forms, select molds with pronounced textures. Consider corrugated metal sheets or intricately carved wooden blocks. These impart tactile surfaces to the clay.
For asymmetrical drape forms, strategically place weights (e.g., beanbags, chains) on the clay sheet during drying. This manipulates the sag and creates organic, unbalanced profiles.
Experiment with layered drapes. Apply a thin slip coating of contrasting color to the clay before draping. As the clay stretches over the mold, the underlying color peeks through, generating visual interest.
Control drape speed by adjusting the clay’s moisture. Drier clay drapes slower, retaining sharper details from the mold. Wetter clay yields smoother, more fluid shapes.
Create segmented drape molds using multiple separate pieces. After the clay stiffens, disassemble the mold, permitting complex undercuts and overhangs unattainable with single-piece molds.
Fuse multiple draped elements to a central core. Use a textured sphere or polyhedron as the base, attaching individual draped pieces like petals around a flower. Ensures structural integrity and design cohesion.
Consider using plaster bandages to create temporary, customized molds. Apply wet plaster bandages over an object to capture its form. Remove the object and let the plaster harden, providing a unique drape surface.
When firing draped pieces, provide ample support to prevent warping. Employ vermiculite or sand inside hollow forms to counteract the effects of gravity and heat during the firing process.
Joining Forms Seamlessly: Score and Slip Secrets
Achieve invisible joints by scoring surfaces with crosshatch patterns using a needle tool before applying slip. Score depth should be approximately 1/16 inch for optimal grip. Use a flexible rib to smooth the slip after joining, forcing out trapped air.
Slip Recipe for Strong Bonds
For reliable cohesion, match the slip clay body to the clay composition of the structural piece. Add a small percentage (2-3%) of vinegar to the slip to increase its acidity, promoting better bonding. Avoid excessive water in the slip; a yogurt-like consistency is ideal.
Controlling Drying for Joint Integrity
Apply gentle pressure to the bond area during initial drying. Wrap the joint with plastic wrap for the first 24 hours to slow moisture evaporation. Gradually remove the wrap over the next few days to prevent stress cracks. Use a heat gun cautiously to even out drying rates between the juncture and main structure.
Texturing Formed Clay: From Fabric to Discovered Items
To achieve refined textile impressions, use tightly woven, untextured linen or silk. Pre-soak the fabric in water with a small amount of liquid starch. This creates a crisper, cleaner imprint during pressing. For deeper textures, consider cheesecloth or burlap layered multiple times. Apply consistent pressure with a rolling pin or smooth board to transfer the pattern evenly.
Foraged natural elements, like leaves or twigs, offer unique surface enrichment. Select items free from excessive moisture or dirt. Press them firmly into the moist clay. Carefully peel away the organic material after the initial impression, leaving a subtle trace. Note: Some plant matter may slightly stain the material.
Employ repurposed household objects. Corrugated cardboard, rubber bands, or bubble wrap create repeating patterns. Experiment with varying pressure levels. A light touch will result in delicate markings, while a firm application yields more pronounced reliefs. Consider overlapping patterns for added complexity.
Utilize found metal pieces for industrial aesthetics. Embossed sheet metal, expanded metal mesh, or even old gears pressed into the surface provide sharp, defined textures. Lightly oil the metal to prevent sticking. Apply even pressure to ensure a consistent impression. Explore combinations of metal and fabric for layered textural qualities.
When employing found objects, test the texturing on a scrap clay piece. Observe the resulting impression, factoring in shrinkage during the firing process. This allows for refining the technique and ensuring the desired outcome on the primary artwork.
Firing Formed-Plate Creations: Mitigating Distortion and Fracturing
Ensure uniform moisture distribution before bisque firing. Slow drying, especially for intricate forms, is paramount. Cover constructions loosely with plastic for several days, gradually reducing the cover to equalize moisture throughout. Consider using a drying box with controlled humidity.
Apply a slow bisque firing schedule. A ramp rate of 75°C/hour up to 600°C, followed by 100°C/hour until reaching the desired bisque temperature (e.g., 900°C), is a common starting point. Hold at the highest temperature for 20-30 minutes to ensure complete burnout of organic materials.
Support weaker segments during firing. Use alumina hydrate or fine silica sand to prop up cantilevered sections or areas prone to sagging. These materials prevent direct contact with the kiln shelf and distribute weight evenly.
Vitrification firing requires meticulous attention to clay body and glaze compatibility. Differing contraction rates can induce stress. Perform glaze fit tests (using rings or strips) to verify that glaze shrinkage matches clay body shrinkage.
During the glaze firing, implement a controlled cooling cycle. Avoid rapid temperature drops, particularly between 573°C (quartz inversion) and 200°C. A slower cooling rate (e.g., 50°C/hour) helps mitigate thermal shock.
Pre-heat the kiln before introducing ware. A gradual warm-up minimizes the risk of thermal shock, especially with thick or complex fabricated items. Aim for a starting temperature of around 100°C.
Employ firing cones to accurately monitor the firing process. Cones offer a visual indication of heat work, accounting for both temperature and time, and can reveal inconsistencies within the kiln.
Consider using low-shrinkage clay bodies. Stoneware or porcelain recipes formulated for minimal volumetric change during firing will lessen stress on joins and intricate details.
Q&A
I’m a complete beginner. What’s the simplest project I can try to get started with slab building?
A great starting point is a simple tile or shallow dish. You just need to roll out a slab of clay to a consistent thickness – about ¼ inch is good – and then cut it into the desired shape. You can use a template or freehand it. Add some texture by pressing leaves or other objects into the wet clay. Once it’s bone dry, bisque fire, glaze, and fire again!
I’ve seen some amazing slab-built forms that don’t look like they’re made of flat pieces. How do you create curved or rounded shapes using slabs?
There are a couple of approaches. One is to create a template for the curved shape and gradually form the slab around it, scoring and slipping the edges to join them. You can use molds, like bowls or even inflatable forms, to support the clay while it dries. Another technique is to use many small, slightly curved slabs that, joined together, create a larger curved surface. It requires patience, but the results can be stunning.
What kind of clay is best for slab building? I’ve had problems with warping and cracking in the past.
A clay body with grog (pre-fired clay particles) is highly recommended. The grog provides strength and reduces shrinkage, minimizing the risk of warping and cracking, especially when working on larger pieces. Mid-range stoneware or porcelain with grog can be excellent choices. Experiment with different clay bodies until you find one you like and that works well with your firing temperatures.
I’m interested in adding decorative elements to my slab-built pieces. What are some techniques I can use?
The possibilities are vast! You can use sprig molds to create raised decorations, carve designs directly into the clay (sgraffito), apply colored slips or underglazes for surface decoration, or even incorporate found objects into the clay before firing. Consider using stencils with colored slips for sharp, repeating patterns. Remember to experiment and let your creativity guide you!
How do you avoid seams showing on slab-built pieces? My joints always seem to be visible, ruining the aesthetic.
Careful scoring and slipping are key! Score deeply, using a crosshatch pattern, on both surfaces to be joined. Apply a generous amount of slip (clay mixed with water to a creamy consistency). Press the edges together firmly, removing any excess slip that squeezes out. Then, use a tool like a rib or wooden spoon to smooth and blend the seam. Depending on the piece, you could add a small coil of clay to the inside of the seam for added strength and then blend that into the corner. Slow drying under plastic will also help minimize cracking at these joins.