What actually goes wrong in home pottery studios

No real studios were visited and no case studies were gathered for this article, so nothing here is presented as a story about a particular workshop. What is here instead is the set of failure mechanisms that conservation and materials literature already describes, matched to the decisions a home potter controls.

What to take away

• Most studio failures trace back to one of four mechanisms: underfiring, glaze fit, soluble salts and handling.
• Firing temperature decides whether a pot is porous, and porosity decides most of what follows.
• Crazing is not a surface effect. It opens the body to staining and to whatever is in the food.
• Handling and storage cause more breakage than any process step.

Underfiring is the root of several problems

The physical change that firing produces has a threshold. Preservation guidance on ceramic collections puts it plainly: only when clay is fired above about 1652 degrees Fahrenheit, or 900 degrees Celsius, do the particles bond through sintering. Below that the body stays porous and absorbs liquid; above it the ware becomes harder and less porous but more brittle.

Laboratory measurement shows the same change in numbers. A university materials course records that unfired green clay beams broke at roughly 37 newtons while fired beams took about 54, that water of hydration is driven off around 350 degrees Celsius, and that firing turns the material hard, dense, more durable, impermeable to liquids and brittle.

A pot that was underfired looks finished and behaves badly: it weeps, it stains, it fails in the freezer or the dishwasher, and no glaze rescues it.

The four mechanisms, and what each asks of you

Mechanism	What you see	What prevents it
Underfiring	Porous, weeping, staining ware	Cones in every firing; one clay body
Glaze fit failure	Crazing, or glaze flaking off	Test the glaze on your body at your cone
Soluble salts	White bloom, surface damage	Keep ware out of contact with soil and salts
Handling	Chips, cracks, breakage	Support the base, never carry by a handle

Crazing is a structural problem

The same preservation guidance describes crazing as a network of fine cracks in the glaze layer, caused when the glaze contracts faster than the clay body, and notes the consequence: crazing exposes the clay body and leaves it open to staining. On functional ware that means every crack is a route into a porous body.

That is why crazing gets fixed by changing the glaze or the body rather than by refiring or by applying it differently. The mismatch is in the materials.

Handling breaks more pots than firing does

Conservation practice for handling ceramics is short and worth copying at home. Pick an object up underneath its center of gravity and never by a protruding element. Remove lids and pedestals and carry them separately. Never hand an object from one person to another; put it down on a stable surface instead. And for slippery or fragile pieces, nitrile or vinyl gloves are preferred over cotton.

Those four rules cost nothing. They cover almost every avoidable breakage in a home studio, and they pair with the firing discipline and the making habits that prevent the rest.

Common questions

How do I know if my ware is underfired?

Weigh a fired test tile, soak it for a day and weigh it again. A large gain in water means it did not vitrify, whatever the controller said.

Can I use a crazed mug?

For your own use, with care. The cracks hold moisture and residues, and on a porous body they can go all the way to the clay, which is why crazed ware is not sold as functional.

Is any of this different for hand-built work?

Not in mechanism. Uneven wall thickness makes hand-built pieces more prone to drying cracks, but firing and glaze fit behave the same way.

Should I keep failed pots?

Keep a few and label them. A shelf of known failures is the fastest reference you will have when a new fault appears.