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A Stainless Steel Bitcoin Wallet

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This project is to make your own Stainless Steel Bitcoin Wallet. (https://en.bitcoin.it/wiki/Cold_storage)

You can see it in action here: 

Please, don't send any Bitcoins to the address on the wallet. If you must send them somewhere, how about here: 13AEtsPjyDm8SdhQFcwUMDJZYgR5hteZPS  :)

Its possible to etch stainless without anything particularly exotic. (I used a bench-top power supply, but thats about it for even remotely out-of-the-ordinary.)

We will use the laser-printer toner-transefer method to make a mask, then apply it to our target steel, and then etch! 

A Note About Safety

This etching process is safer than many others since there are no acids involved. However, there are still some things to consider.

First, the process will split the water into hydrogen and oxygen gases. Hydrogen is flammable and when mixed with oxygen, down right explosive. You don't want to let those gases accumulate. Use plenty of ventilation to prevent the gases from concentrating.

Second, stainless steel is made stainless by adding Chromium to the steel. After etching, there will be contamination in the water from the steel. The only part you have to worry about breathing and environmentally is the hexavalent chrome or (Cr VI). Avoid breathing the fumes from the etching and treat the waste water an an environmental hazard. (It is probable that the concentrations from this project will be too low to officially be considered a hazard, but rather than have it tested, lets just treat it as such.)

Feel free to reuse the solution as much as you can, but when it is time to dispose of the solution you should let it evaporate and then dispose of the remaining solids by tossing them in with some other stainless scrap. Find a  local machine shop that works with stainless and toss it in with their stainless scrap.
 
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mbainrot6 months ago
Instead of using Salt to increase the continuity of the water, try it with sodium bicarbonate (bicarb soda), that should avoid any chlorine-like fumes and avoid stinking out your place making it smell like a pool
ledshed6 months ago
Nice. Rather than wax, you can spray with black paint then use a fine wet and dry paper to remove the paint from un-etched areas.
neo716658 months ago
I have a friend at a chrome shop that let's me sneak my stuff in with theirs when it gets picked up. I do finishes on gun barrels and knife blade so in a year I only have a few gallons.
brendanjerwin (author)  neo716658 months ago
That sounds like another good way to dispose of the solution. Thanks for the hint.
neo716658 months ago
There is way more to those bubbles than water being split. You just created hazardous waste and hope you treat it as such (don't pour it in the yard or down the drain). I also wouldnt suggest doing this in any enclosed building without proper vents. I have a 16x16 roll up door on each end of my shop and still do my etching outside with a 48 inch fan blowing on my back.
oldmicah neo716658 months ago
Hey Neo. thanks for the heads up: Where do you dispose of the used waste?
Call your local hardware store and ask about paint and solvent disposal locations.
brendanjerwin (author)  ToolboxGuy8 months ago
Please don't treat this as a paint or solvent. Although the concentrations are not likely to be very high, the materials in the etching solution are probably not dealt with the same way as the materials in paints and solvents. See the updated first section for hints on disposal.
Thanks... simpler answer than I had imagined. :)
What is the hazardous waste? The primary product is rust.

Given enough current density and time, you might manage to make a dilute solution of bleach (NaClO) or drain cleaner (NaOH). It's difficult to imagine this being concentrated enough to be a hazardous material. Could you clarify this?
brendanjerwin (author)  ElizabethGreene8 months ago
I got some clarification on the hazards (see update in the first section). Stainless has Chromium added, and that is the source of hazard. It sounds like you may have been thinking of mild steel?
Klappstuhl8 months ago
"Please don't use this key" doesn't seem a safe way to discourage people from trying...

"I too like to live dangerously" comes to mind though! :3
Quesnelquack8 months ago
Congratulation on making the process work with stainless steel using minimalistic approach. I have given up stainless as it is much harder to do that mild steel. Just a couple of comments:
1) If you are going to do several of these, Press-n-Peel is far superior than any paper for doing the transfers
2) During the etching process you will certainly get hydrogen on the cathode. However, if you have gas coming out on the anode this is more likely to be chlorine which is toxic.
3) The residual electrolyte will contain trivalent and, more importantly, hexavalent chromium which is toxic and an environmental hazard. Another argument for using mild steel.
4) I wonder if the card would work if made of copper or brass. The electrolytic process is even easier using acidified copper sulphate.
trailleadr8 months ago
You should really consider using an image editor to blur out your QR codes.
brendanjerwin (author)  trailleadr8 months ago
But then you couldn't see the quality if them! No, this particular wallet isn't going to be used, it's just for you, Dear Internets.
Oh I see. :)
akaihola8 months ago
When scanning the keys for verification, it's important to boot the computer from a live CD. Otherwise you'll have to destroy the hard drive afterwards since there probably are traces of the private key QR code in swap space or temporary files. Also, keep the computer off-line during the process (disconnect ethernet cable, and disable Wi-Fi and Bluetooth in the BIOS). The mobile phone must be off-line when scanning the private key QR code (no SIM card, and disable Wi-Fi, Bluetooth and NFC), and you must destroy the phone immediately afterwards. I wouldn't store significant amounts in the etched address without these precautions.
brendanjerwin (author) 8 months ago
I chose the size mostly because it was what I had on hand.

I did find that the text does much better when I can get it larger, but if you restrict it just to the QR codes (my script configures them to allow 30% data loss!) you could probably get it smaller.
oldmicah8 months ago
Great project! I'm going to start timing all my projects in EFR's. (episodes of futurama)

I'd like to do it, but would like to try it smaller. Did you choose the size (3x6) because of resolution issues or do you think it would scale down?

many thanks!
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