🎧 Making a Faceted Agateware Pitcher Haakon Lenzi

Appears in the June/July/August 2025 issue of Ceramics Monthly.

The audio file for this article was produced by the Ceramic Arts Network staff and not read by the author.

Agateware is a process in which different colored clays are layered to resemble stones such as agate or marble. Unlike other marbling techniques, agateware patterns are not just a surface decoration, the colored clays run through the body of whatever form they take. The bottom of each piece tells the story of how the clays were combined. It also makes for some of the prettiest broken pottery shards you’ve ever seen. Let’s use a faceted agateware pitcher of mine to explore this process further.

How Agateware is Made

When it comes to agateware, a choice needs to be made between using commercial clays or adding pigment to clay. Since agateware involves layering clays of different colors, you can either choose to combine already available clay of contrasting colors or add pigment to a single white clay to produce a variety of colors. If using different clay bodies, make sure they shrink at a similar rate; otherwise, the layered clay will crack in the drying and or firing. While there are commercially available colored clays, I prefer to work with my own palette and add various pigments to Standard’s 257 English Grolleg Porcelain. The pigments I use are Mason Color Works stains, specifically 6315 Zirconium Vanadium Blue, 6097 Dark Red, 6410 Canary Yellow, and 6666 Cobalt-Free Black. I fire these colors to cone 8 in my oxidation kiln and have found that all of these colors, except for Canary Yellow, can be fired to cone 10 in reduction, though the tonality is different. 

Colored porcelain can be prepared by either mixing stain into a slip before drying it out to plastic clay or the stain can be wedged into the clay by hand. If mixed as a slip first, add 10% stain to reclaimed clay (based on the bone-dry weight), mix with water, and then dry the slip out in plaster vats. 

Note: Be sure to wear gloves when handling Mason stains (especially while throwing) to avoid heavy metal poisoning through skin absorption. For further information, refer to the Material Safety Data Sheet (masoncolor.com/safety-data-sheets).

Wedging Stain into Porcelain

I work in a small studio with an extensive color palette. To conserve space, I choose to wedge stains into my porcelain. A physically intense process, each batch takes 1½–2+ hours of wedging. The day after it feels like I did a thousand push-ups. Given the volume of pots I make, each batch of clay is prepared in 10–20-pound (4.5–9-kg) increments. 

To calculate how much stain to add to color 10 pounds of porcelain, let’s assume that 10 pounds (4536 grams) of plastic clay has approximately 20% water and therefore has approximately 3269 grams of dry material. So we need to add 363 grams of stain (10% of 3269 grams, both numbers are rounded up).

To create the colored clay, start by placing the stain in a mortar and pestle to grind, adding water until it’s a paste (1). Do this in batches, mixing each batch well to avoid clumps. The clumps are unattractive and can cause cracking when fired. To conserve energy, separate 3–5 pounds (1.4–2.3 kg) from the 10 pounds of plastic clay, and work the stain paste into this smaller section. Cut the clay into several cross-sections and smear the stain paste on one side of each cross-section (2). Then stack (3) and begin wedging (4). 

At first, do whatever it takes to combine the stain with the clay. You might even try squishing the clay through your fingers. Once all the stain is worked into the smaller piece of clay, combine it with the larger piece using slap wedging (5, 6). Cut the colored clay and unstained clay into cross-sections and stack them in an alternating fashion. Then cut it in half with your wire tool and slam one piece over the other. Make sure that the layers are horizontal and parallel to each other, resembling a layer cake. Repeat this process until the layers are gone and the color of the clay is even. 

Layering Clays to Throw Agateware on the Wheel 

To begin making agateware, lay out similar-sized balls of stained clay (7). Cut cross-sections of each and begin stacking them, slamming them together to prevent air bubbles (8, 9). Once combined, pick the whole thing up and drop it a few inches off the table, then rotate and repeat until you’ve gone all the way around, 

sealing off all of the seams. Then throw the clay towards yourself, rotate, and repeat to stretch it out into a log. From there, cut it up into smaller pieces to be thrown on the wheel (10). Make sure the clays are all the same consistency before throwing. This can be achieved by wrapping the combined clays in plastic and allowing it to sit overnight. 

Throwing Agateware on the Wheel 

To throw on the wheel, ensure the layers of clay are stacked vertically, like books on a shelf, so the clays form a spiral in the finished pot. While centering, don’t cone up and down more than three or so times, otherwise the clays will blend together. Likewise, if you make too many pulls you will lose the swirling agateware effect. While centering and throwing, the colors will blend together on the surface (11). Don’t worry, the pattern is still there and will be revealed with a metal rib at the end of the pulling process (see 13). 

Making a Faceted Agateware Pitcher 

To make this faceted pitcher, throw a thick cylinder, accounting for the clay removed by the cheese slicer. Throwing a pot that is both thick and even can be more challenging than expected. Use a pin tool to ensure the wall thickness is even by sticking it through the wall until it hits your finger at various points on the cylinder (12). Just as when you check the bottom thickness of your pot, the holes will close up once you run a finger or rib over it. 

Use a metal rib to remove excess moisture and reveal the pattern (13). To create the facets, start at the top of the cylinder and drag a cheese slicer down quickly without stopping (14, 15). Use your bat pin as a registration guide. I have a little saying when altering on the wheel, “Let the bat pin be your guide!” Spin the wheel 180 degrees until you are at the other bat pin and repeat the cut with the cheese slicer. Proceed to make your third and fourth cuts in between the first two, so that you end up with four symmetrical facets. Finally, cut the last four facets in between the original four and you should have a symmetrical eight-sided pot (16). The faceting creates a stunning effect similar to marbled paper. 

Then use a wooden rib with round edges to shape the pot from the inside (17, 18). If unfamiliar with this technique, feel free to just use your hand, but the rib allows for shaping with no added water. I like to brace my right elbow into my core and then touch my right hand to my left bicep or anywhere on my left arm to act as an anchor during the one-handed shaping process. 

Once shaped, immediately make the spout by holding the rim with your left hand and two dry fingers (19). With your right hand, wet your pointer finger and cradle it back and forth to create a spout. If the tip of the spout is below 90 degrees from the rim, the spout should theoretically not drip. 

After allowing the pot to dry, use a sharp trimming tool to both remove some weight and make the agateware pattern appear more graphic (20). If the clay is too wet, the trimming tool will smudge up the surface. If the pot gets too dry, consider rehydrating. 

Adding the Handle 

Use black porcelain to make the handle with whatever handle-making method you prefer (21). For this pitcher, I pulled the handle from a lug of clay. After pulling, the handle should be dry to the touch, yet still plastic, perhaps the same consistency as clay out of the bag. Score and slip both the top of the handle and the pitcher. Attach with some pressure and a wiggle (22), then immediately bend the handle into shape. Score, slip, and attach the bottom of the handle (23). The last finishing touch is a traditional pottery move, run a wet thumb back and forth at the bottom of the handle to create a groove, which serves as a visual anchor (24, 25). 

Notes on Simplifying the Process 

• If your studio has multiple clays that fire to the same temperature, have a similar shrinkage rate, and have contrasting colors, experiment with them. Make sure to test before investing time into multiple finished pieces. 
• When making your own colored clay, you can use any white clay, it doesn’t have to be porcelain. 
• Try mixing only one colored clay as a start. When combining with white clay, cut each ball into three cross-sections (six once combined). 
• Try mixing up 2–3 pounds instead of 10+ pounds. It will go surprisingly far. 
• Save your agateware reclaim and use that when making your black clay or a mystery color (usually brown). 

Finishing 

Once bisque fired, sand the pot with a 200-grit wet sanding pad/sheet. The exterior is then left unglazed to showcase the agateware surface while the interior is glazed with a liner. After the glaze firing, wet sand again to ensure a smooth surface. Start with 200 grit and work your way up 500+ grit if you’re up for it. 

the author Haakon Lenzi is a lifelong New Yorker. He maintains an active studio practice out of his East Harlem studio, where he produces his signature Lenziware pots. To learn more, visit www.haakonlenzi.com. 

June/July/August 2025: Table of Contents

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