In this lesson
- find out what a seed phrase backup has to survive
- compare backups on paper and on metal
- decide where to store the backup and how many copies to keep
The seed phrase is the one thing in this whole course you cannot afford to lose. Yet the backup has to last for years – and a lot can happen in the meantime: fire, water, tidying up, moving house, a curious visitor. A good backup survives all of it.
What you protect against#
| Threat | What helps |
|---|---|
| fire | metal (stainless steel), a second copy elsewhere |
| water and damp | metal, or paper in a waterproof cover |
| fading and decay | metal, or good paper and permanent ink |
| a thief or a curious visitor | a discreet hiding place, no "bitcoin" label |
| loss when tidying or moving | a fixed place that you (and a trusted person) know |
| a digital leak | never a photo, cloud, email or file |
Paper#
The paper from the wallet's box is fine to start with: write legibly with permanent ink and put it in an envelope and a waterproof cover. Its weaknesses are obvious – paper burns, gets wet and fades over the years.
Metal#
Metal backups are plates or capsules in which you stamp the words or assemble them from letter tiles. The first four letters of each word are enough; the word is uniquely identified by them.
- Stainless steel melts only at around 1,400 °C; a house fire does not usually get that hot.
- Aluminium melts at around 660 °C – it is not suitable as a backup against fire.
Metal costs tens of euros. For savings whose loss would hurt, it is cheap insurance.
Where to store it and how many copies#
- One copy at home in a fixed, discreet place – not in the drawer with the device.
- A second copy elsewhere – with a trusted person or in a bank safe deposit box. It protects you if you lose your home.
- More copies = more places where someone can find it. Two copies in two places are a sensible compromise.
Check the backup once a year: is it legible, complete and in its place?
No digital backup
No photo on your phone, file on your computer, email, cloud or note in an app. Every device connected to the internet is a place the seed phrase can leak from – and you find out only when the money is gone.
Common myths#
- "I have it in a safe, nothing can happen." A safe protects against a thief, not always against fire and water.
- "I will label it 'Bitcoin seed phrase' so my family finds it." So will a thief. Instructions for your family belong elsewhere – that is lesson ten.
- "One copy is enough." One fire or one flood and you have nothing.
Summary
- A backup must survive fire, water, time, thieves and tidying – and must never be digital.
- Paper is fine to start; for larger amounts stainless steel is better (not aluminium).
- Two copies in two places are a sensible compromise between loss and exposure.
- Once a year, check that the backup is legible, complete and in its place.