Sweep sats to a self-custody wallet

Who is this guide for?

If you’re using Flash to receive and store Bitcoin, you’re currently using a custodial lightning wallet. While convenient for daily transactions, keeping all your Bitcoin in a custodial solution isn’t ideal for long-term storage.

This guide is for anyone who:

• Has accumulated Bitcoin in their Flash wallet
• Wants to reduce counter-party risk for their savings
• Plans to hold Bitcoin for the long term
• Values financial sovereignty and self-custody

We’ll walk you through setting up a self-custodial wallet and moving some of your funds there for secure, long-term storage.

Why is self-custody important?

The fundamental Bitcoin principle is: not your keys, not your coins.

When your Bitcoin is in Flash or any custodial wallet, you’re trusting that service to:

• Keep their systems secure from hackers
• Manage their finances responsibly
• Honor your withdrawal requests
• Remain operational over time

While Flash employs industry-best security practices, any custodial service introduces counter-party risk. Self-custody eliminates this risk by giving you complete control over your Bitcoin.

Benefits of self-custody include:

• Full ownership: Only you can access and move your funds
• Censorship resistance: No one can freeze or seize your Bitcoin
• Reduced third-party risk: No exposure to service provider problems
• Privacy: Hold Bitcoin without KYC information
• Long-term security: Properly secured Bitcoin can be held for generations

Ready? Let’s go!

Flash makes it easy to move your Bitcoin to self-custody without requiring advanced technical knowledge. You have two primary methods:

Method 1: Direct On-Chain Withdrawal (Recommended for beginners)

Flash allows direct withdrawals to on-chain Bitcoin addresses:

1. Choose a self-custody wallet

   • Mobile options: Blue Wallet, Blockstream Green, or Muun
   • Hardware options: Ledger, Trezor, or ColdCard (for larger amounts)

2. Set up your wallet

   • Download and install your chosen wallet
   • Create a new wallet and follow the setup process
   • CRITICAL: Write down your seed phrase on paper and store it securely. This is your backup!

3. Get your Bitcoin address

   • In your new wallet, find the “Receive” section
   • Copy your Bitcoin address (starts with “bc1” or “3” or “1”)

4. Withdraw from Flash

   • Open Flash and go to the Wallet tab
   • Tap “Send” or “Withdraw”
   • Select “On-chain withdrawal”
   • Paste your Bitcoin address
   • Enter the amount (consider starting with a small test amount)
   • Confirm the withdrawal

5. Verify receipt

   • On-chain transactions typically take 10-60 minutes to confirm
   • Check your self-custody wallet to confirm receipt
   • You can track the transaction status using a block explorer like mempool.space

Method 2: Using a Flash Exchange Point (For Lightning to on-chain conversion)

Flash’s peer-to-peer network enables in-person exchanges:

1. Set up your self-custody wallet (follow steps 1-3 above)

2. Find an Exchange Point

   • Open Flash and go to the Map tab
   • Look for Exchange Points in your area (orange pins)
   • Alternatively, use the Flash Support chat to find remote exchange partners

3. Arrange the exchange

   • Contact the Exchange Point through Flash Chat
   • Agree on an amount to swap
   • Share your Bitcoin address with them

4. Complete the exchange

   • Send sats to the Exchange Point via Flash Lightning
   • They’ll initiate an on-chain transaction to your address
   • Verify the transaction ID and track it on mempool.space

Recommended Self-Custody Workflow

For optimal Bitcoin management with Flash:

1. Use Flash as your daily spending wallet

   • Keep a modest amount for everyday transactions
   • Benefit from instant, low-fee Lightning payments

2. Periodically sweep to self-custody

   • Set a threshold (e.g., when your Flash balance exceeds $100)
   • Move excess funds to your self-custody wallet
   • Consider automating this with recurring calendar reminders

3. Layer your security

   • Small amounts: Mobile wallet apps
   • Medium amounts: Hardware wallets like Ledger or Trezor
   • Large amounts: Air-gapped solutions like ColdCard or multi-signature setups

Key Concepts: Lightning, On-Chain, and Self-Custody

Bitcoin

Bitcoin is a decentralized digital money system that operates without central control. It enables peer-to-peer transactions globally without requiring trusted intermediaries.

Key properties:

• Limited supply: Only 21 million Bitcoin will ever exist
• Permissionless: Anyone can use it without approval
• Decentralized: No single entity controls the network
• Immutable: Transactions can’t be reversed or modified
• Verifiable: Everyone can audit the entire system

The Bitcoin base layer prioritizes security and finality over speed and cost, making it ideal for final settlement and storage.

Lightning Network

Lightning is a second layer built on top of Bitcoin that enables:

• Instant payments: Transactions confirm in seconds
• Near-zero fees: Makes micropayments practical
• Scalability: Handles millions of transactions per second
• Privacy: Enhanced transaction privacy compared to on-chain

Flash primarily uses Lightning for its payments, giving you the speed and low costs needed for everyday transactions.

On-Chain vs Off-Chain

• On-chain transactions: Recorded directly on the Bitcoin blockchain

  • Higher security and finality
  • Higher fees (especially during high demand periods)
  • Slower confirmation times (minutes to hours)
  • Best for larger amounts and final settlement

• Off-chain transactions (Lightning): Occur outside the main blockchain

  • Instant confirmations
  • Extremely low fees
  • Perfect for small, frequent payments
  • Requires channels to be funded and online

Custodial vs Self-Custodial

• Custodial solutions (like Flash’s default wallet):

  • A third party holds your private keys
  • Simple and convenient
  • No technical knowledge required
  • Introduces counter-party risk

• Self-custodial solutions:

  • You alone control your private keys
  • Full sovereignty over your funds
  • Requires responsible key management
  • No counter-party risk

Most Bitcoin users adopt a hybrid approach: custodial solutions for daily spending and self-custody for savings. This combines convenience with security in a practical way.

Remember: Self-custody is a skill that improves with practice. Start with small amounts, get comfortable with the technology, and gradually increase your self-custody holdings as your confidence grows.