Ethereum-Public Mint bridge two-way functionality is now live

Starting today, you’ll be able to move your MINT tokens back and forth across Ethereum and the Public Mint mainnet. Here’s how to do it.

Published in

Public Mint

6 min readJan 17, 2022

We have just opened the second lane on the Public Mint–Ethereum bridge, in line with our roadmap. This means that MINT holders can now migrate their tokens from the Public Mint mainnet into the Ethereum blockchain.

🚨WARNING: Read before migrating MINT 🚨

A few important things to note before you start the process:

DO NOT try to send your MINT tokens directly from your Public Mint Wallet to the Ethereum mainnet, as they run on different networks. Doing so may lead to irrecoverable loss of your funds! Follow the steps outlined below to migrate your tokens.
If you’ve chosen to manage your own private key when creating your Public Mint Wallet, make sure you have a copy of the file. We DO NOT have access to private keys and cannot recover your funds if you lose it!
For the moment, we highly recommend that you only use the bridge on a desktop, and not on mobile devices.
We highly recommend you use Metamask and Chrome/Chromium-based browsers while interacting with the bridge. While other browsers and wallets may work, we currently offer support only for this setup.

A quick note on gas fees

Using a bridge to move assets between blockchains usually requires paying for gas fees in both origin and destination chains, whichever the direction of the move.

While we have waived Public Mint blockchain gas fees for the bridge, you must still pay for gas on Ethereum for each transaction, in or out — and ETH gas prices have been obscenely high for some time now.

When migrating MINT from Ethereum to Public Mint, Ethereum costs are quite obvious as the transaction is paid in ETH, on the Ethereum network.

However, when migrating from the Public Mint mainnet to Ethereum, we need to charge in USD (the native currency of our blockchain). To do that, we need to do some conversions along the way:

We get a quote of the ETH gas cost from Etherscan every five minutes;
We then convert it to USD at the ETH-USD price at that moment;
This is the USD price that the transaction will have in the Public Mint network.

We’d like to stress that we DO NOT charge any fees on top of that, and we don’t make any profits on the conversion. The entirety of the amount is used to cover ETH gas on the Ethereum network.

We are currently studying how to optimize this design, but right now this is how it works.

Migrating MINT: Public Mint to Ethereum

Make sure your MINT tokens are in your Public Mint Wallet on the Public Mint mainnet, and that you have enough USD in your wallet to cover the transaction fees (roughly around the level of a Uniswap transaction).

Before starting, you’ll have to either import your Public Mint Wallet in Metamask, or send your tokens and USD for fees to an address you control via Metamask:

Configure the Public Mint mainnet on Metamask (if you haven’t already). You need Metamask to use the bridge at the moment.
Import the Public Mint Wallet (where you hold your MINT) into Metamask. If you started with the web wallet and chose the advanced “Manage your wallet” option, you should have a .JSON file containing your private key. On Metamask, click on the top right icon, then click Import account. On the Select type drop-down, pick JSON file and upload yours. You should now have your Public Mint Wallet address imported to Metamask, and your USD and MINT balance will should be showing (you might need to add MINT manually — this is the contract address: 0xC312642DaD4490D7f351391b85488d34778E9667)
Send MINT and USD to Metamask address you control: If you have lost your JSON file or created your Public Mint Wallet using the Google or Apple integrations, the best thing to do is to follow Step #1 and just send your MINT and the USD to cover the transaction to one of your existing Metamask-controlled addresses.

Using the bridge, step by step

After the setup above, here’s how to use the bridge:

On Metamask, under the Networks drop-down up on top, select the Public Mint Mainnet.

2. Head to https://bridge.publicmint.com/ and click Connect Wallet. You’ll be prompted to connect with your Metamask wallet. Accept the request to move forward.

3. The Home Network field should read Public Mint, and the Destination Network field should be Ethereum. Please note that you can’t edit these fields — they’re pulled automatically based on which is the current active blockchain on Metamask.

4. Fill the large box with the amount of MINT that you’d like to migrate. The Total balance field shows your current MINT balance on the active blockchain (in this case, on the Public Mint Mainnet).

5. Fill in the Destination Address field with your Ethereum address, or the Ethereum address where you’d like to send your MINT to. Right below that field, you’ll notice the current estimated cost of the transaction.

6. Click the Approve transaction button to allow the bridge to access your tokens. Approve the transaction on Metamask and wait for it to go through. You only ever need to do this once, on the first time you use the bridge. You’ll see the text in the button text.

7. Finally, click the Send transaction button and approve it via Metamask again.

8. After a few minutes (usually around ~20 Ethereum block confirmations, but sometimes more), your MINT tokens should arrive on your Ethereum Wallet.

That’s it! If you’d like to send MINT back into the Public Mint Mainnet, just do the same process, but starting from Ethereum.

The only differences will be that there won’t be an estimated fee field (you’ll pay ETH fees directly from Metamask), and that under Destination Address, you should fill in with a Public Mint address instead.

If you have any questions or encounter any problems, please contact us on Telegram or via customer support channels.

Thank you, and see you on the other side!⚡️

About Public Mint

Public Mint is an open and complete blockchain platform for fiat money, where funds are fully collateralized and held on deposit with regulated, FDIC-insured institutions. Public Mint offers an open, fiat-native blockchain and APIs, ready for anyone to build fiat-based applications and accept credit cards, ACH, wire transfers, stablecoins and more. On top of that, the Public Mint EARN platform offers users automated and diversified returns on USD assets, leveraging the power of blockchain and DeFi.