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Ruhplush

Safety & care

You control the heat, which means you can overdo it.

A microwavable object has no thermostat and no shut-off, because it has nothing to shut off. What it has instead is a physical guarantee — no power source, so it leaves the microwave at its hottest and only cools from there. Here is what that does and doesn't protect you from.

Metal content
None

Zip teeth, slider, pull tab and filling. All of it, deliberately.

Can it overheat itself
No

Nothing to power it. Hottest at second zero, cooler every minute after.

Heating time
TBC

Tested on real domestic microwaves, printed on the label, erring low.

Certification
ASTM F963

Third-party lab report, not a logo. EN 71 in Europe.

Why “another thirty seconds” is a bad instinct

Skin damage is about time, not just heat.

The table beside this is derived from Moritz and Henriques, 1947 — the work that still underpins modern safe-contact standards. Three things fall out of it.

Below about 43 °C, sustained contact is broadly fine. That is the range the clinical heat-therapy trials use, and the range the instruction on the label will aim at.

Above about 50 °C, the margin collapses. Not a gentle slope — a cliff. Thirty extra seconds in a microwave is a much bigger change than it feels like, and “you’d notice and move” stops being true the moment you fall asleep.

The clock runs backwards in your favour. Unlike anything mains- or battery-powered, this object’s hottest moment is the first one. Every minute after that moves it further down the table rather than holding it in place. That is the one genuine safety advantage of doing it this way, and it is why we’d rather you under-heated it and went back for another twenty seconds.

There is a slower version of the same problem: repeated exposure well below burn temperature, over weeks, produces the mottled brown staining called erythema ab igne. It is the classic hot-water-bottle injury, and worth knowing about whatever you’re warming yourself with.

Approximate time to skin injury at a given contact temperature.
Surface temperatureTime to injury
44 °CAbout six hours
48 °CAround ten minutes
51 °CAround two minutes
55 °CUnder thirty seconds
60 °CAround five seconds

The label instruction will aim below the first row of this table.

Looking after it

Two parts, three rules.

  1. 01

    Heating it

    Whole, cover on, nothing removed. Follow the time on the label and stop there — if it needs more, give it another short burst rather than one long one. Never run it dry-hot in a microwave you've just used for something else, and never leave it running unattended, which is advice that applies to a microwave generally.

  2. 02

    The cover

    Unzips off the core and goes in the machine. Cool wash, no tumble dryer — high heat is what kills a short-pile fabric and turns it into the shiny thing you were trying to avoid.

  3. 03

    The core

    Glass micro-beads in a sealed, compartmented pouch. It never goes in water and never needs to; the seal is what makes the wash cycle a non-event. If the pouch is ever damaged, stop heating it and contact us.

Safety questions

The ones people actually ask.

Is it safe to fall asleep with it?
Warm things you sleep on deserve a straight answer, so: this one has no power source, which means it cannot get hotter than it was when you took it out of the microwave. From that moment it only cools. That removes the failure mode that makes cheap electric plush worth worrying about, and it doesn't remove the other one — a too-hot object held against skin for a long time. Heat it to warm, not to hot, and keep a layer of clothing between you and it.
How hot does it get?
As hot as you make it, which is the honest answer and the uncomfortable one. There is no sensor and no thermostat in a bag of glass beads — the only control is the number of seconds. We will test that number on real domestic microwaves and put it on the label and on this page, and the instruction will err low. For reference, the clinical trials on heat therapy use around 40 °C, and cheap electric heated plush has been measured at 57 °C, which is far past anything useful.
Why is there no metal anywhere in it?
Because the whole thing goes in the microwave with the cover on, and metal in a microwave arcs. So the zip is fully non-metallic — nylon coil or moulded acetal teeth, plastic slider, plastic pull tab — and the filling is glass micro-beads rather than the steel ones a lot of weighted products use. We ask the supplier for the zip's spec sheet rather than a verbal yes, because this is the one detail where a substitution nobody mentions becomes a fire.
Can I wash it?
The cover unzips off and goes in the machine, cool wash, no tumble dryer. The core stays out. It never needs washing because the filling is sealed in its own pouch — nothing gets in, so nothing has to come out. Full instructions ship with it, and they'll be on this page before anything is sent.
Will the filling go off, or start to smell?
No, and that's most of the reason it's glass rather than wheat. Grain and flaxseed fillings warm beautifully and then, over a year or so of being heated, go rancid — that faintly toasted farm smell everyone who has owned one recognises. Glass micro-beads have nothing in them to spoil. Cherry pits are the one alternative we're sampling, and they behave the same way.
Is it safe for children?
It is designed as an adult wellness object, not a toy, and it is not intended for young children — a heat source and 1.5 kg of weight are both reasons to keep it out of a cot. We test to ASTM F963 because it is the strictest relevant standard for the materials and construction, not because we're aiming it at children.
What if I have reduced sensation in my skin?
Then please talk to a doctor before using any heat source, including this one. Diabetic neuropathy and similar conditions blunt the pain response that would normally tell you to move, and that response is the safety mechanism.

Sources

  1. 01Moritz A. R., Henriques F. C. — Studies of thermal injury (American Journal of Pathology, 1947)The foundational time–temperature work on skin burns; still the basis of modern safe-contact standards.
  2. 02ISO 13732-1:2006 — Ergonomics of the thermal environment: touching of surfacesSets safe contact temperatures and durations for warm surfaces.
  3. 03ASTM F963 — Standard consumer safety specification for toy safetyThe US standard, mandatory by federal law since April 2024. Materials, small parts, seam and attachment strength, drop testing, labelling.
  4. 04EN 71 — Safety of toysThe European equivalent, for anything sold that side of the Atlantic.
  5. 05DermNet — Erythema ab igneThe skin change caused by repeated low-grade heat exposure below burn temperature.

The waitlist

We'll publish the certificates too.

When the first samples are tested, the results go on this page and into The Warm-Up — including anything that comes back worse than we hoped.

One confirmation email, then roughly twice a week. Leave whenever you like — one click, no login.