If it leaves the wall, you know in seconds.
Not when you get home. Not when someone finally notices. The second the frame lifts off its hook, your phone lights up — and if the sensor goes quiet after that, you hear about that too.
Damage arrives quietly.
A radiator fails in January while you're away. The room cools, the humidity climbs, and inside a week mould has taken hold on the back of the canvas — where nobody will think to look for months. Nothing looked wrong. Nothing made a sound. Vokter watches how fast conditions are moving, not just where they end up, so you hear about it on the first day, while it's still a phone call to a neighbour.
It learns your walls.
Every house has a rhythm. Sun on the south wall at two. Heating at six. Windows thrown open on the first warm Saturday in April. Vokter learns yours, and stops mentioning things that are merely Tuesday — so on the day it does speak, you believe it.
Three steps. Then you forget about it.
- 01
Stick the sensor to the back of the frame.
It's the size of a large coin. No tools, no wiring, no holes. Nothing touches the work itself.
- 02
Plug the hub in anywhere in the home.
It has its own connection — no Wi-Fi password, no router settings, no app pairing dance. It keeps working through a power cut.
- 03
Then leave it alone.
The hard limits work from the first minute. Over the following weeks Vokter also learns what normal looks like in your home — and then it goes quiet, and stays quiet, until it shouldn't be.
Built on the method museums use.
A cheap sensor gives you two fixed lines and shouts when a reading crosses one. Set them tight and your phone never stops — the afternoon sun on a south wall is enough. Set them loose and you find out far too late.
European Standard EN 15757 describes a better approach, developed for museums and historic buildings. Instead of one number for every room in every country, it starts from what this place actually does across a year, and measures everything against that. Your wall in February is not your wall in July. A single number cannot be right in both.
Vokter follows that method. It learns the slow seasonal rhythm of your room and sets its alert band around it — narrow enough to catch a real problem, wide enough to ignore a sunny Tuesday. The band moves with the year. It never moves past the limits that are wrong for any painting, anywhere.
- Your normal
- Learned from your room, following EN 15757. Sharper the longer it runs.
- Hard limits
- 40–60% humidity, 16–25°C. The band never drifts past these, no matter what your room does.
- Sudden change
- A sharp move means something has happened — a leak, an open window, a failed radiator. You hear about it the same day.
In the box
- The sensors.
- Three of them, 48 mm across and 12 mm thick, matte black or off-white. Each sits on the back of a frame or on the wall beside it, and you'll stop noticing them inside a week. Five years on one coin cell, which you can change yourself in about ten seconds.
- The hub.
- Plugs into any socket. Connects on its own — no Wi-Fi, no configuration. Covers a typical apartment; large or old houses with thick walls may need a second one, and we'll tell you before you order.
- The app.
- Live readings, full history, and the alerts. Nothing else.
Measurements
| Temperature | ±0.2 °C |
|---|---|
| Relative humidity | ±1.8 % |
| Movement | Immediate, with tilt and impact |
| Reporting | Full history every day, alerts instantly |
| Battery | 5 years, user-replaceable |
| Range | One hub covers a typical apartment |
Readings are logged every five minutes and delivered daily, so your history is complete rather than sampled. Alerts don't wait for the daily upload — they go out the moment they happen.
Vokter Home
€20 a month. Three sensors and a hub.
One sensor gives you a number. Three give you a comparison — and the comparison is what finds the problem. An exterior wall and an interior wall in the same room can differ by several per cent of humidity, and it's the exterior one that does the damage. Three sensors is enough for most homes: the wall you worry about, the wall you don't, and the room nobody goes into.
Everything is included — the hardware, the connection, the app, the alerts, and replacements if anything ever fails. There's nothing to buy and no second invoice.
€240 a year. Less than you spent on the frame.
12-month minimum term. Cancel any time after that and send the hardware back.
Another sensor — €5 a month. For another room, another wall, or the piece you just brought home.
Another hub — €10 a month. For large houses, thick walls, or a second address.
Most people need Vokter Home. If what you're protecting doesn't stay in one place, read on.
Vokter Roam
€15 a month. One sensor. No hub. Goes anywhere.
Some things don't stay on a wall. A piece out on loan. A work in storage. The painting that moves with you between two houses, or the one you're not entirely sure you'll get back.
Roam carries its own connection, so it needs nothing around it — no hub, no Wi-Fi, no socket. It reports temperature, humidity and movement wherever in the world it happens to be, and unlike the wall sensors, it can tell you where that is. Indoors, roughly. Outdoors and moving, precisely.
One trade-off, stated plainly: it holds a year on a charge rather than five. Once a year, it wants an evening on a cable.
Vokter started with four of my grandfather's paintings on a bad wall. Here's the rest of it.
Questions
Will it damage the artwork?
Nothing touches the work. The sensor mounts on the back of the frame or on the wall beside it, using adhesive that removes cleanly. If you'd rather not attach anything at all, it works on a nearby shelf — slightly less precise about movement, just as good about the air.
How often will it interrupt me?
Almost never — and that's the design goal, not a happy accident. Once it has learned your rooms, most homes see a handful of alerts in a year. Anything chattier and you'd mute it, and a muted sensor is worth nothing at all.
What happens if the power goes out?
The hub has its own battery and keeps working. The sensor never needed mains power in the first place.
What if someone unplugs the hub, or takes the sensor?
You get told. Vokter expects to hear from every sensor on a schedule — silence is treated as an event, not as good news.
Can you track it if it's stolen?
No, and we'd rather say so plainly. Vokter tells you immediately that something has moved and then gone out of range. That gives you and the police a precise time and a head start, which is far more than most people have. It does not follow the object across town, and any product that promises you that on a five-year battery is being optimistic with you.
Does it replace my insurance?
No. It's the part insurance can't do. A policy handles the loss after it happens; Vokter is about the hours before, when the situation is still fixable.
Is three sensors the right number?
For most homes, yes — and it's three rather than one because a single reading has nothing to be compared against. Put one on the wall you're worried about, one on an interior wall in the same room, and one wherever you'd never think to look. If you have more walls than that, sensors are €5 a month each.
What's the difference between a Vokter sensor and Vokter Roam?
The wall sensors are small, invisible and last five years, but they need a hub in the building to speak through. Roam carries its own connection and works anywhere on earth, including in the back of a van — but it's larger, it knows roughly where it is, and it needs charging once a year. If your art stays home, you want sensors. If it travels, you want Roam.
Do I need Wi-Fi?
No. The hub brings its own connection. There is nothing to configure.
Is my data private?
The readings are yours. We don't sell them, we don't share them, and you can export or delete everything at any time.
I travel a lot. Does that change anything?
Only in that it matters more. Vokter asks nothing of you while you're gone — no checking in, no app to open, no weekly report to read. If your phone stays quiet, everything is fine. If it doesn't, you'll know in time to ask someone to go over and look.
Does it work in a summer house I'm rarely at?
That's one of the better uses for it. An unheated house in winter is exactly where humidity does its worst work, unobserved. You'll need mains power for the hub, but nothing else.
What happens when I order?
Nothing is charged, and nothing is committed. You tell us what you'd like and we reply within a working day or two with an offer — usually with a question or two about your home first, because the right number of sensors depends on the building. If the offer suits you, we send the hardware. That's when the subscription starts.
Nobody insures the part that matters.
You know which one it is. Most people with art have one piece they'd turn back for — and it's usually not the valuable one. It's the one with a story attached. A wedding present. Something bought badly and far too early, before you knew anything, that turned out to be right.
A policy can replace a sum. It can't replace the object, and it has nothing at all to say about the slow version of losing it — the dry winters, the wall that was always a little too warm, the damage that arrives so gradually that no single day was the day it happened.
That's the part Vokter is for.
Go away for three weeks. Think about something else.
€20 a month. Ten minutes to set up. Then quiet, until there's a reason.