In the Potter's Kitchen: Sip Slow and Enjoy Andrea Burns

Appears in the Jan/Feb 2024 issue of Pottery Making Illustrated.

Parents of young children and cold coffee seem to go hand in hand. I always heard that before becoming a mother, but the blatant truth of it was still shocking when my time came. This is what gave me the idea to create luminary mug warmers. I wanted something both functional and beautiful, and nothing balances those two qualities better than porcelain. When a small tealight candle is placed inside one of my mug warmers, the translucent porcelain lights up to reveal glowing hand-carved details. There’s no longer a need to rush my coffee time, and no reheating my coffee when the kids distract me and I forget about it for the fifth time (it’s inevitable). And that, friends, may be the most beautiful thing about these. 

Measure Twice Cut Once 

It is very important to be as exact as possible with the measurements of your mug warmer. There is a really fine line between making a mug warmer that’s too small (which will either snuff out the candle flame or increase the likelihood of sending the mug above into thermal shock), and making one that’s too large (which won’t actually keep your beverage warm). My dimensions took nearly a year of trial and error to figure out. That being said, if I gave you measurements of my wet clay parts, your final post-firing measurements wouldn’t come out the same as mine unless you were also using a 14% shrinkage clay. For this reason, the measurements given are of what the final mug warmer will be when it’s finished and glaze fired. You will want to add your clay’s shrinkage percentage to the numbers I am giving to ensure you end up with accurate final measurements. A shrink ruler is a great tool to have on hand for this. It is a ruler with different shrinkage percentages calculated into it, making exact measurements like this a breeze. 

I take three measurements with my shrinkage ruler: one from rim to rim (A), one on the exterior wall from the base to the rim (B), and one of the base from edge to edge (C). 

Throwing the Mug Warmer Parts 

To begin, weigh out two portions of clay; one 14 oz (397g) and the other 8 oz (227 g). These weights may be slightly more or less depending on the shrinkage of your clay, but this is a good place to start. Begin by centering and opening the larger ball of clay, making sure to leave about ⅓ inch of clay (or slightly less than a cm) on the bottom to accommodate trimming a foot ring. Widen the interior to just under 4 inches (10 cm), as you’ll want the final shape to have an exterior diameter of 4 inches (10 cm). Pull your walls to a height of 2¼  inches (5.7 cm) and square everything up with a 90° angle rib (1). Wire the form off while the wheel is slowly spinning to apply even pressure around the form and reduce warping. 

Throw a flat disk with the smaller ball of clay to 4½ inches (11.4 cm) wide and ⅓  inch (1 cm) thick. Don’t wire this section off of the bat—more on that later.

Connecting the Pieces 

Set the two halves out to firm up until they reach a soft leather-hard consistency. At this point, you’ll want to slip and score the rim of the larger piece and the outer edge of the flat disk (2). Place the larger piece on top of the cookie and wiggle it into place. Either tightly wrap your mug warmer in plastic or set it in a damp box for a couple of days so that moisture from the seam can be evenly distributed into the rest of the form. 

Trimming and Shaping 

Once the seam has set up, it’s time to trim. The piece should still be attached to a bat, so it won’t need to be centered. Place your bat on the wheel and trim a foot ring flush with the edge of the wall (3). This will be the top of your mug warmer. Follow this with a 2-inch (5-cm) diameter hole in the center (4). This leaves an opening for the candle heat to reach the mug above it. After the hole has been cut, refine the edge (5), then run a wet brush along the inside seam while the wheel is spinning. This will smooth out extra score lines and any slip that may have come through to the inside. Smooth everything with a sponge and wire off the bat. 

Flip the warmer over, secure to the wheel with extra clay, and trim a foot into the bottom side as well (6). 

Next, you’ll cut the opening for a tealight candle to fit through (7). I have a paper template I trace on to make it easier, which is an arch shape that measures 2¾ inches (7 cm) wide and 1¾  inches (2.5 cm) tall (these measurements are from a standard ruler). However, as long as the opening will accommodate a standard tealight candle after shrinkage, it could be any shape you’d like. Smooth everything out and cover the piece in plastic, allowing it to come to leather hard before the next step. 

Detailing 

I also love to accentuate the translucent nature of the porcelain by carving imagery into the walls (8). I like to carve about halfway through the thickness of the walls to ensure that the imagery will glow when there’s a candle inside. 

Next, add additional airflow holes and optional details to the walls. Chances are that if you don’t enable additional airflow, the candle flame will not get enough oxygen to stay burning hot. I typically add about 15 extra small holes around the form as well as a pattern of them around the candle opening (9). My favorite tool for this is a flex-shaft rotary tool equipped with a small drill bit, but you could also turn the drill bit by hand or use a hole punch tool. 

Finally, I recommend testing out your leather-hard form with a candle (10). Although this is not foolproof because the form still has much shrinking to do, it does give you an idea of its functionality ahead of time. If the candle doesn’t stay burning when a mug is placed on top, you know it needs a bigger candle opening or additional airflow holes in the walls. Make any adjustments you need before setting it out to fully dry and then bisque firing it. 

Glazing 

I dip my mug warmers in a clear glaze, but the possibilities are endless. One thing to consider is whether or not you’d like to glaze the flat top rim area that will make contact with the bottom of your mug. If you leave it unglazed your mug won’t slide as much, but you do run the risk of coffee drip stains on the bare clay over time. I tend not to do this when working with white porcelain especially because these items will end up in customers’ homes. This is why I designed the upper ring to hold the mug in place even if it slides around a little. However, if you’re working with a darker stoneware this probably wouldn’t be a major concern and leaving that area unglazed is a nice touch. 

Tips for Using Your Mug Warmer 

• Only use standard-size tealight candles with your mug warmer (12) (1½ inches diameter × ½  inch height (4 cm × 1.3 cm)). 
• Always pour a hot beverage into your mug before placing it on the warmer. This is not meant to heat up cold beverages, but to keep hot ones hot. 
• Never put or leave an empty mug over the candle flame. 
• And lastly, while these have been rigorously tested with 100% success, I cannot guarantee the integrity of every mug you own. Please use at your own risk. 

Andrea Burns is an artist and educator living and working in Allendale, Michigan. She sells her pottery and colored porcelain, and teaches various classes in her studio. She enjoys gardening, cooking, and spending time in nature with her husband and two children. To see more of her work visit www.potsbyandrea.shop and follow her on Instagram @pots.by.andrea.