釉の上か下か
The porcelain body is not what the dishwasher threatens. The decoration is — and whether it is under the glaze or on top of it decides the answer.
Wikipedia’s articles set out the two methods. Underglaze decoration is painted on before the transparent glaze is applied and fired; because the glaze then covers it, the decoration is completely durable and the surface has a uniform sheen. Overglaze decoration is applied on top of the already fired and glazed surface and fixed in a second firing at a relatively low temperature — which is what allows its wider, more vivid palette, since those pigments would not survive the temperature the porcelain body needs.
That lower second firing is the whole story. The colours fuse onto the glaze rather than under it, so they are exposed to whatever the surface is exposed to. Blue-and-white porcelain is the classic underglaze case, historically limited to a narrow range of colours — cobalt blue above all — precisely because few pigments survive the high firing. A piece with a broad, bright palette is more likely to be carrying it above the glaze.
Gold and metallic rims are the sharper case, because gilding is applied over the glaze by nature — there is no underglaze gold. That is also why gold-rimmed pieces are the standard exception to microwave use: metal in a microwave is a separate problem from wear. And the porcelain body itself is genuinely tough, described as completely vitrified, hard and impermeable even before glazing, which is why the answer is about the surface rather than the material.
Listings rarely say “overglaze” or “underglaze” outright, but they often say enough: hand-painted enamel and a wide bright palette point one way, blue and white and a single cobalt point the other. If the piece is in front of you, the sheen tells you more than the description does. And where a maker states dishwasher suitability, that is the answer for that piece — it is their decoration and they know which side of the glaze it is on.
No shop link here. This is a question about a piece you already own or are looking at, and the check costs nothing. The lacquerware guide below is the other half of the same table: urushi and the dishwasher is a shorter conversation.
Sources The other guides鉄瓶と鉄急須
One boils water and gives you iron. Putting the other on heat cracks its lining for good.
土鍋の目止め
Unglazed clay is porous until rice starch seals it — one simmer, once.
漆器の手入れ
Dishwasher, microwave, sunlight. All normal, all irreversible on urushi.
片刃と利き手
Ground on one side only. The wrong side does not cut badly — it does not work.
土鍋とIH
Induction heats metal, not clay. Most donabe never get warm — and cannot be converted.
熊野筆の毛
Not a quality ladder. Natural hair holds powder; synthetic is built for cream and liquid.
砥石の番手
There is no dominant standard behind the number. Two #1000 stones can cut differently.
茶筅の穂数
Carved from a single piece, so a snapped tine is not a repair. The tine count is a spec, not a score.
錆と経年変化
One protects the blade, the other eats it. Scrubbing the wrong one leaves the knife worse off.
三徳・牛刀・菜切
Two of these are the same knife. And a nakiri suits either hand; the usuba it resembles does not.
ダマスカスの意味
The original ceased production around 1900. Since 1973 the word has meant pattern welding — decoration.
白紙と青紙
Blue holds an edge longer and is harder to sharpen. Which is better depends on how often you sharpen.
抹茶の等級表示
ISO and Japanese labelling define how matcha is made. Neither defines a grade.
硬度と刃角
Western knives sit at 52–58 and 20–22°; harder steel is what permits 15–18°. Higher is a different bargain.
まな板と刃
Glass dents, rolls and chips edges rapidly. Wood is self-healing — but grain matters more than "hardwood".
刃物を贈るとき
A gifted knife is said to sever the relationship. The custom is that the recipient hands back a coin.
金継ぎのキット
Real urushi cures in a humid box over days to weeks. A kit that sets in an hour is something else.
沈香と伽羅
The scent exists because the tree was infected. Uninfected wood is pale and light — whatever was added.
箸の形と作法
Pointed where Chinese ones are blunt. And two ordinary gestures read as funeral rites.
墨と膠
Sumi is soot held by animal glue. India ink needs no binder and dries waterproof on its own.
柄の木と嵌合
Friction-fitted, not bonded — so it can be replaced. And a D-shaped handle is made for one hand.
硬化した漆
Uncured urushi gives most people a rash. Cured, reactions are possible but less common.
刃こぼれ
Repair is subtraction — grind past the chip on a coarse stone, then work back up the grits.