How to swap wETH for ETH on Polygon network?

Question

The current largest mining pool Ethermine has an option to be paid in wETH through the Polygon network instead of in ETH on the mainnet.

Through MetaMask on the Polygon network, I see my wETH in my wallet, but MetaMask does not offer an option to swap to ETH, only other wrapped tokens. Is it possible to use MetaMask to swap wETH to ETH? If I use an exchange like Uniswap, can I pay for the gas fees in wETH or do I already need ETH to pay for fees? Will my swapped ETH exist on Polygon or on mainnet?

Answer 1

First of all, the "eth" asset exists in different forms across Ethereum and Polygon. For each blockchain, we have one utility token and other erc20 compliant tokens (+ other standards).

1. Ethereum eth - the utility token
2. Ethereum weth - the erc20 wrapper for eth
3. Polygon matic - the utility token
4. Polygon wmatic - the erc20 wrapper for matic
5. Polygon weth - an polygon erc20 representation for polygon eth that was bridged from ethereum mainnet

Second of all, any transaction requires gas paid in the native utility token of the chain. So for ethereum you will pay native eth, while for polygon you will pay native matic.

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Regarding your bridging question, if you ask to be paid in weth on Polygon, you will receive (#5) the polygon erc20 weth token in your wallet. To bridge it to Ethereum Mainnet you will use a service such as the Polygon Bridge or Hop Exchange. These will convert your polygon weth -> to mainnet (pure) eth.

For Hop you will need to sign one transaction on polygon (requiring utility token for gas: matic) for the transfer.

For the Polygon Bridge (from what I remember) you will need to sign two transactions. One on polygon (requires matic) to send the polygon weth and one on ethereum (requries eth on mainnet) to receive the weth. For this you need to consider having some eth for gas on mainnet in the account before starting the transfer.

Answer 2

I contacted MetaSwap support. They confirmed that ETH exists as wETH on Polygon and MetaMask browser extension does not support bridging currently. Instead I can use a bridge like Polygon or Hop to bridge the tokens across networks.

To make transactions within Polygon requires MATIC tokens as the gas token. Previously there were MATIC faucets to provide a little MATIC to get started. However, Polygon bridge has Swap for gas token which can directly convert wETH to MATIC to get started with transactions. I converted 1 MATIC which should be enough to do at least several dozen transactions.