Uncured urushi is an allergen that gives most people a rash. Cured urushi is the same compound after it has polymerised, and that changes the answer.
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Wikipedia’s article on the lacquer tree describes the process and the outcome together. The sap contains urushiol, an allergenic irritant, and curing the applied sap means drying it in a warm humid chamber for 12 to 24 hours, during which the urushiol polymerises to form a clear, hard, waterproof surface. On the finished state the article is direct: once hardened, reactions are possible but less common. Tableware is listed among the common applications.
So the honest answer has two parts. Cured urushi is not the same hazard as the liquid — polymerisation is what a finish is — but “less common” is not “impossible”, and the article does not say otherwise. People who react to poison ivy share the sensitivity, since urushiol is what makes poison ivy what it is, and a small number of people do react to finished lacquerware.
Two things follow that are practical rather than theoretical. Damage matters: a chipped or worn lacquer surface is no longer the continuous cured film the description assumes, which is one more reason the dishwasher is worth avoiding beyond the cosmetic damage. And the literature cited in the lacquerware article includes work on heat treatment rendering Japanese lacquerware hypoallergenic, which tells you the question has been taken seriously enough to study rather than settled by assertion.
A finished piece from an established maker has cured — that is what makes it a finished piece. The situations worth more care are the ones where curing is in question or the film is broken: a repair you have done yourself, a kit whose contents you cannot identify, or a bowl whose lacquer has chipped through. If you know you react badly to poison ivy, that is the same compound, and worth weighing before buying rather than after.
This page reports what the sources say and is not medical advice. If you have a known urushiol sensitivity, the question is one for a doctor rather than for a craft site.
SourcesThe scent exists because the tree was infected. Uninfected wood is pale and light — whatever was added.
There is no dominant standard behind the number. Two #1000 stones can cut differently.
Glass dents, rolls and chips edges rapidly. Wood is self-healing — but grain matters more than "hardwood".
Two of these are the same knife. And a nakiri suits either hand; the usuba it resembles does not.
JIS defines it — and the definition says most washi today is machine-made from chemical pulp.
Carved from a single piece, so a snapped tine is not a repair. The tine count is a spec, not a score.
Not a quality ladder. Natural hair holds powder; synthetic is built for cream and liquid.
ISO and Japanese labelling define how matcha is made. Neither defines a grade.
Ground on one side only. The wrong side does not cut badly — it does not work.
Blue holds an edge longer and is harder to sharpen. Which is better depends on how often you sharpen.
One protects the blade, the other eats it. Scrubbing the wrong one leaves the knife worse off.
Western knives sit at 52–58 and 20–22°; harder steel is what permits 15–18°. Higher is a different bargain.
Repair is subtraction — grind past the chip on a coarse stone, then work back up the grits.
A gifted knife is said to sever the relationship. The custom is that the recipient hands back a coin.
Friction-fitted, not bonded — so it can be replaced. And a D-shaped handle is made for one hand.
The usual fix starts by soaking it. A seiro maker calls soaking strictly forbidden.
Dishwasher, microwave, sunlight. All normal, all irreversible on urushi.
A prefectural institute put eleven lacquer films through JIS Z 2801. Most came back undetectable.
The original ceased production around 1900. Since 1973 the word has meant pattern welding — decoration.
It conducts heat badly. That is the product — and it is also why it cracks.
Unglazed clay is porous until rice starch seals it — one simmer, once.
Induction heats metal, not clay. Most donabe never get warm — and cannot be converted.
Real urushi cures in a humid box over days to weeks. A kit that sets in an hour is something else.
Not urushi against epoxy. Whether the material states food-contact compliance.
Pointed where Chinese ones are blunt. And two ordinary gestures read as funeral rites.
Sumi is soot held by animal glue. India ink needs no binder and dries waterproof on its own.
The body is impermeable. It is the decoration that is exposed — and you can feel which kind it is.
One boils water and gives you iron. Putting the other on heat cracks its lining for good.
The spots appear in the first week. The makers’ association says do not take them off.
The form is settled by a 2003 paper. The amount is not settled by anything.
