# Bridge

SANDchain Testnet currently supports the [ZKsync Bridge](https://sandchain-bridge.caldera.xyz/bridge). The Testnet version of the bridge allows for supported ERC20 tokens to be bridged between Silica (SANDchain Testnet) and Sepolia (Ethereum Testnet). With SAND being the token initially supported. 

To access the bridge, you can either navigate there directly (<https://sandchain-bridge.caldera.xyz/bridge>) or by clicking on the applicable link in the [SANDchain Caldera Hub](https://sandchain-hub.caldera.xyz/).&#x20;

<figure><img src="/files/0Doy7T2RhY38OWPmEIwy" alt=""><figcaption></figcaption></figure>

#### **Using the Bridge**

<figure><img src="/files/g0kpXcsuVaAim3c9jPha" alt=""><figcaption></figcaption></figure>

At the launch of the testnet, the bridge will only support bridging of Testnet SAND between the Ethereum and SANDchain Testnets.&#x20;

To use the bridge, you will first need to connect a supported wallet. Although the bridge does support a number of wallet choices, **we recommend Metamask at this stage to ensure that you have full compatibility with SANDchain**.

<figure><img src="/files/UZEayUtpwrDX4g9WU7Q5" alt="" width="375"><figcaption></figcaption></figure>

In this guide scenario, we will consider that the goal is to send SAND to Sepolia. So from SANDchain to Ethereum.

1. Connect Wallet - this wallet will be the sender
2. In the “From” panel select “Silica”, and this will automatically set the “To” panel to “Sepolia”

<figure><img src="/files/rgk58MUVwPQXJzSAlRaG" alt=""><figcaption></figcaption></figure>

If you are not already connected to the appropriate network (in this case Silica), click “Change wallet network to Silica”. This will automatically change the network for the connected wallet.&#x20;

{% hint style="warning" %}
Although these are testnet transactions, they still require transaction fees to be paid. If sending from Silica, then SAND is required. If sending from Sepolia, then ETH is required. For reference: the “Max” in the “From” field represents the total amount of SAND which can be bridged as it already considers the transaction fee.&#x20;
{% endhint %}

3. Choose which wallet address on Sepolia you wish to receive the testnet SAND - by default it will be set to the connected wallet address

<figure><img src="/files/woq6BsfcDLdBbUeuTwH7" alt=""><figcaption><p><em>Your connected wallet address is set as the default receiver</em></p></figcaption></figure>

Input either an [ENS](https://ens.domains/) or the wallet address if different to the sending wallet address

<figure><img src="/files/F155ezhkLaRe3reIGVcH" alt=""><figcaption></figcaption></figure>

4. Input the amount of SAND you want to bridge in the “From” panel
5. Click “Continue”

<figure><img src="/files/8TZHLf403PX9fGyHRisz" alt=""><figcaption></figcaption></figure>

{% hint style="warning" %}
When you use ZKsync Bridge to transfer out of SANDchain, the SAND bridged will not be automatically deposited into your wallet. You will need to manually claim the SAND once it is ready. This claim transaction requires a transaction fee to be paid.&#x20;
{% endhint %}

6. Click “I understand, proceed to withdrawal”

<figure><img src="/files/OZAVyvS7gKhSnzTCPBo0" alt=""><figcaption></figcaption></figure>

7. Click “Bridge Now”

<figure><img src="/files/ogfHsHsFFQqNrFPiKp4X" alt=""><figcaption></figcaption></figure>

Once you have approved the transaction on your connected wallet, the bridging transaction is submitted.&#x20;

#### **Claiming Bridged Tokens**

You can monitor the status of the bridging transaction in the bridge UI, but you do not need to stay on this page or keep it open. Closing the page once the transaction is confirmed, will not affect the transaction.&#x20;

Once the transaction is complete, you will see "Go to Claim", and you can claim the bridged tokens.&#x20;

1. In the Bridge, click "Transfers"&#x20;
2. Click "Go to Claim"

<figure><img src="/files/qw0r91TT3in6E7pOJzpL" alt=""><figcaption></figcaption></figure>

3. If your wallet is not connected to the claiming network (Sepolia in this case), click "Change Network to Claim"

<figure><img src="/files/O4FBGDTV2DOyXSdgTggP" alt=""><figcaption><p>You will be prompted to approve the change in your connected wallet</p></figcaption></figure>

4. Click "Claim Withdrawal"&#x20;

<figure><img src="/files/nbYS2tAWFEGXdjLikF5o" alt=""><figcaption></figcaption></figure>

5. Confirm the transaction from your connected wallet

<figure><img src="/files/zSkJ9qVDIJaMUuetXIK9" alt="" width="375"><figcaption><p>This transaction requires a gas fee to be paid</p></figcaption></figure>

Once confirmed, and the transaction is complete, the bridge tokens will be received in the claiming wallet.&#x20;

<figure><img src="/files/vnCoYpzu0tbcIYU0DyP6" alt=""><figcaption></figcaption></figure>

#### **Bridging to SANDchain**

The bridging to SANDchain is much the same flow as bridging from SANDchain. The only difference is that when bridging into SANDchain, you do not need to claim the bridged tokens, they are automatically deposited into your destination wallet address.

{% hint style="warning" %}
Although you do not need to claim and pay a transaction fee to claim tokens bridged into SANDchain, you will need SAND for any further transactions you intend to do. If using testnet, you can utilise the SANDchain [faucet](/docs/build/faucet.md).
{% endhint %}

#### **Token Approval Limits**

If you have never used the bridge before you will be required to approve a SAND spend limit in your wallet, so that the bridge has permission to transfer your SAND.&#x20;

1. Click “Approve SAND Allowance”

<figure><img src="/files/MqYMYujcJ0E1gI5qhcle" alt=""><figcaption></figcaption></figure>

2. Click “Confirm” in your connected wallet - the “Allowance” here being referred to as the “Spending cap”

<figure><img src="/files/gcm9Wv7XMY1fDHUwzTvp" alt="" width="375"><figcaption></figcaption></figure>

Once confirmed, the bridge will now be able to transfer your SAND tokens to the amount which you approved.

<figure><img src="/files/ziNDLqstazYwJ7Cl3l1k" alt=""><figcaption></figcaption></figure>

{% embed url="<https://sandchain-bridge.caldera.xyz/bridge>" %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://sandchain.gitbook.io/docs/build/bridge.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.