Choose a Clay Body That Can Take a Knock

A mug that lives beside the kettle takes more punishment than almost anything else in the kitchen. It gets filled with boiling water, dropped into the sink, stacked badly, and shoved through the dishwasher. So start with a clay body that deserves the job: a mid-fire stoneware that vitrifies somewhere between 1220°C and 1260°C. Vitrified stoneware is dense and strong, and if the glaze fits properly the finished mug will barely absorb water at all.

Earthenware fires lower and comes in lovely warm colours, but it stays porous and chips more readily, which matters little for a plant pot and a great deal for something you drink from twice a day. For throwing, choose a smooth, plastic stoneware that centres without a fight. For hand-building, a body with 10–20% grog gives you slabs that hold their shape and resist cracking as they dry.

Throwing or Hand-Building: Both Make Fine Mugs

On the wheel, weigh out 400–500g of clay for a mug holding roughly 300–350ml. Centre well, open the floor, and pull the walls in three or four gentle passes rather than one aggressive one. Aim for walls of 4–5mm and a base of 6–8mm — thick enough to hold heat, thin enough not to feel like a brick. Leave the rim slightly thicker than the wall just below it; that small swell is what your lip rests against.

Hand-builders can make excellent mugs from a slab rolled to 6mm, wrapped around a cylinder and joined with scored slip. Pinch pots work too, particularly for smaller espresso cups, and coiling gives you control over taper and belly. Whichever route you take, remember shrinkage: a stoneware body will lose 10–12% between wet clay and glaze firing, so a mug that measures 400ml on the bench may finish near 330ml.

Get the Handle Right and the Mug Gets Used

Handles are where most homemade mugs fail — not structurally, but ergonomically. Pull them from the same clay as the body so they shrink at the same rate. A comfortable handle is roughly 20–25mm wide, 8–10mm thick at its deepest point, and leaves a gap of 25–30mm for the fingers. Test it with your own hand before it dries.

• Join the top of the handle 15–20mm below the rim, so your thumb has somewhere to rest.
• Attach the lower end at the widest part of the belly, not down at the foot.
• Score both surfaces, use thick slip, and press a small coil of soft clay into each join for extra strength.
• Blend the joins with a damp finger or sponge, then compress them firmly.
• Dry the mug slowly, resting it on its side or upside down so the handle does not pull away.

Rims, Feet and the Details That Decide Durability

A rim of 4–5mm, rounded rather than knife-edged, survives washing-up far better than a thin one. Slightly flare the lip outward as you finish it — that gentle curve guides the liquid and feels pleasant against the mouth. Any sharp edge or burr will chip, and once a rim chips the mug is finished.

Trim a modest foot ring so the mug sits flat without wobbling. Keep the foot a millimetre or two narrower than the widest part of the wall for stability, and smooth it with a damp sponge after bisque firing. A tidy foot also stops glaze from pooling underneath, which is what makes mugs stick to kiln shelves.

Glazes: Food-Safe, Well-Fitting and Practical

Use only glazes formulated as food-safe and lead-free, and check that they are rated for dinnerware. A simple liner glaze on the interior, with something more decorative outside, is a reliable approach for beginners.

Glaze fit matters more than colour. If the glaze crazes — those fine spider-web cracks — it is under compression and the body is shrinking away from it. Crazed surfaces can harbour bacteria and will stain with tea within weeks. Adjust the recipe by adding silica or reducing flux, or try a slower cooling cycle in the kiln, which often solves the problem outright.

• Test tiles first: pour boiling water in, leave lemon juice standing for 24 hours, then run twenty dishwasher cycles.
• Draw on the glaze with a permanent marker; if it wipes clean, the surface is sound.
• Leave the foot unglazed, or wipe it clean before firing.
• Check that the glaze is safe for microwave use if you intend to reheat drinks.

Firing, Testing and Living With Your Mugs

Bisque around 1000°C, then glaze fire to your stoneware's maturing temperature, with a soak at the top and a slower cooling ramp of roughly 60–80°C per hour. This gives the glaze time to heal and the body time to settle, and it noticeably improves durability and resistance to thermal shock.

Before you hand a mug to anyone, put it through your own kitchen. Fill it with boiling water straight from the kettle, let it cool, wash it by hand, then run it through the dishwasher twenty times. Note the weight of clay you used, the handle position, the rim thickness. The second batch is always better than the first, and the tenth batch — matching in size, comfortable in the hand, ringing faintly when tapped — is the one you will reach for every morning without thinking about it.