How to Choose a Metal Seed Backup

Once you have decided to use metal for your seed phrase backup, the next decision is which type. Metal seed backups use three broad approaches: stamping, engraving, and tile-based assembly.

The right choice depends on the tools you have, your preference for permanence over flexibility, and whether you want 24-word capacity in a compact form.

If you haven't decided on metal yet, Paper vs Metal Seed Phrase Backups covers how the two compare. If you want to understand the broader backup system before getting into product selection, How to Store Your Seed Phrase is the right starting point.

What Capacity Does a Metal Backup Need?

Before comparing methods or products, confirm that any product you are considering supports 24 words. Most hardware wallets default to generating a 24-word seed phrase, but some older or simpler wallets generate 12-word seeds. Verify which length your device generates before purchasing.

Most metal backup products encode words using the BIP39 four-letter abbreviation standard. Every word in the BIP39 word list is uniquely identified by its first four characters. No two BIP39 words share the same opening four letters. This means Abandon and Ability are distinguished as ABAN and ABIL without needing the full word. A 24-word seed encoded as four-letter abbreviations requires 96 character positions (24 words at four characters each).

Stamping the full word is possible but unnecessary, and roughly doubles the stamping work. Most products listed in this article are designed for 24-word four-letter abbreviation storage.

After creation, verify each abbreviation against the full BIP39 word list. Confirm that each four-letter abbreviation correctly resolves to the intended word before relying on the backup.

What Recording Methods Are Available?

The selected backup method determines the tool requirement, the permanence of the marks, and the recovery reliability.

• Letter stamping: This uses individual letter and number stamps struck with a hammer into a steel plate one character at a time. The result is deeply embedded characters that are physically durable and readable even after fire exposure. Errors are permanent, so careful work and immediate verification matter.

• Grid punching: This uses a steel plate with a pre-printed alphanumeric grid. Rather than stamping each character directly, you use a center punch to mark the position on the grid corresponding to each letter. This eliminates the need for a full alphabet stamp set and reduces the total marks required, making the technique faster to execute and the results easier to verify at a glance. SeedPlate by Coinkite uses this technique for quick and secure seed plate storage.

• Washer systems: With this method, you give each seed word its own circular metal washer, the kind used in construction with nuts and bolts. The word number and its first four letters are punched around the outer edge of each washer. Once complete, the washers are stacked in order on a bolt and secured with a nut. The assembled stack is compact, and the nut prevents reordering without disassembly.

• Engraving: This uses an electric rotary tool, such as a Dremel with an engraving bit or a dedicated electric engraver, to scribe characters into the plate surface. Engraving is faster than letter stamping, easier to execute accurately, and allows for minor corrections before the backup is finalized. The marks are shallower than stamped characters and may be slightly less readable after high-temperature fire exposure.

• Tile-based systems: This uses pre-made metal letter tiles assembled inside a housing. No tools are required for this approach and tiles are repositionable before the housing is locked, which means mistakes can be corrected during assembly. The trade-off is that the housing must maintain its structural integrity through fire. If the container fails under extreme heat, tiles can scatter and lose their arrangement.

Within the stamping family, letter stamping produces the most durable marks, grid punching reduces the tooling requirement, and washer systems add a compact per-word form factor. Across all methods, execution quality and post-creation verification matter more than the method chosen.

Does Stainless Steel Grade Matter?

Most metal backup products use grade 304 stainless steel, which is the right choice for the majority of users. Grade 304 contains 18% chromium and 8% nickel, with a melting point of approximately 1,400 to 1,450°C, well above any residential fire temperature. It resists corrosion in normal freshwater environments, indoor humidity, and most mild chemical exposure.

Grade 316, sometimes called marine grade, adds molybdenum to the alloy. This improves resistance against salt water, chlorides, and highly corrosive environments. The melting point is similar to grade 304. The corrosion resistance advantage is meaningful in specific scenarios.

Grade 316 is worth considering in three situations: a coastal storage location with salt air or water exposure, a buried backup in humid soil, or a very long-term storage scenario expected to span many decades. For most users storing a backup in a home safe, safety deposit box, or dry indoor location, grade 304 is more than adequate.

How Do I Choose the Right Metal Backup Product?

The right product is the one you will execute correctly. A well-stamped inexpensive plate is more reliable than a premium product assembled without care.

Selection criteria, in order of importance:

1. Confirm 24-word capacity. All products listed above support 24 words. Verify any product not listed here before purchasing.

2. Do you have a stamp set, or do you want to buy one? If yes, SeedPlate or Blockmit provide the most value. If you want stamps included, Stamp Seed is the kit option.

3. Do you want tool-free assembly? Cryptosteel Capsule requires no stamps or engraving tools.

4. Is marine-grade corrosion resistance relevant to your storage location? If yes, Stamp Seed's 316 SS is the relevant upgrade.

5. Are you a Coldcard user? SeedPlate is made by Coinkite, the manufacturer of Coldcard. When buying Coldcard devices or other Coinkite products, you can purchase a SeedPlate as part of a discounted bundle and save on shipping above certain thresholds.

All four products meet the minimum security requirement: 304 or better stainless steel at 24-word BIP39 four-letter abbreviation capacity. Verify the backup after creating it and run the full recovery test before depositing significant funds.

For more on the recovery test, see How to Store Your Seed Phrase.