# Replacing Materials on Provided Assets

Let’s use the materials we added to our new library.

1. Open any machine, such as **N_02_PCB_Router.usd**
   * Remember to set your lighting to **Grey Studio**
2. Browse to and select your MaterialLibrary.usd file and  drag it onto the **World(defaultPrim)**

#### NOTE
It should be referenced in the scene rather than loaded as a payload. You can tell the difference by looking for an orange arrow (reference) instead of a blue arrow (payload). References (orange arrows) load automatically and are always accessible, while payloads (blue arrows) can be loaded/unloaded on demand to manage memory usage. For a material library that needs to be constantly available for material assignments, using a reference ensures the materials are immediately accessible without requiring manual loading.

![MaterialLibrary context menu with Convert Payloads to References highlighted.](materials-assembly/images/image18.jpg)

What we want to do here is replace the current material assigned to the side walls of this machine to the **m_PolishedSteel** material created in the previous lesson.

The screenshots show an alternative material. Select **m_PolishedSteel** for this exercise; your surface appearance will differ.

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## **Create a Material Override Sublayer**

1. With your machine asset navigate to the **Layers** panel.
2. Click Create **Sublayer**

![Layers panel with the Create Sublayer control highlighted beneath the root layer.](materials-assembly/images/image37.jpg)
1. Name the sublayer **MaterialOverride.usd** and save it in the same directory as your machine asset.
2. Click **No** when prompted, “Do you want to transfer the root layer contents to the new sublayer?”.
   * We want to keep the original asset data in the root layer and only store our material modifications in the sublayer.
3. Double-click on **MaterialOverride.usd** in the Layers panel to set it as the active authoring layer.

![MaterialOverride.usd selected as the authoring layer in the Layers panel.](materials-assembly/images/image39.png)

Now we’ll replace materials using a centralized materials library through a non-destructive sublayer workflow.

1. Navigate to the **machine asset hierarchy** and choose a metal component (e.g., a frame or housing piece that you want to modify).
2. In the Properties panel, click on the material thumbnail icon under **Materials on selected models**.

![Materials on selected models section with the material thumbnail highlighted.](materials-assembly/images/image29.png)
1. In the Stage, right-click on the selected material and from the context menu choose the **Select Bound Objects** option.

![Material context menu showing Select Bound Objects.](materials-assembly/images/image12.png)

This will select all objects in the asset that share the same source material, allowing you to replace materials efficiently across multiple parts at once.

1. In the viewport, right-click on one of the highlighted parts of the asset and from the context menu select **Assign Material**

![Viewport context menu with Assign Material highlighted for the selected machine parts.](materials-assembly/images/image43.png)

This will open a material assignment window where you can search for replacement materials.

1. In the material assignment window, you can filter by searching “**m_**” in the material dropdown to find materials from your centralized library.
2. Find a replacement material (such as **m_PolishedSteel** from your material library)
3. Select **Ok** to apply the new material to the selected parts.

![Selected Delta PCB router with a blue material applied to its housing.](materials-assembly/images/image9.png)

Continue this workflow until all the materials are replaced with appropriate alternatives from your materials library.

#### TIP
Make sure to save your file as you complete the materials replacement task to preserve your work.

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### **Non-Destructive Material Assignment Benefits**

Notice that the **MaterialOverride.usd** sublayer in the Layers panel now shows content (indicated by a small triangle). This demonstrates that:

* Material assignments exist only in the sublayer, not in the original asset file
* The original asset remains unchanged and intact
* You can easily revert changes by removing or muting the sublayer
* Multiple team members can work with different material variations simultaneously

#### NOTE
When you return to the **MaterialLibrary.usd** file and make a change to the referenced material, that change will propagate to all assets that link to it.

![Delta PCB router with an alternative olive-colored housing material.](materials-assembly/images/image23.png)