---
alias: user-guide-change-experiment-material
description: "Replace the current main material of an experiment and update its sub-material assignments"
---

# Change Experiment Material

:lock: Experiment.**ChangeMaterial**

## Overview

This operation replaces the current main **Material** of an **Experiment** and lets you update its **Sub-Material** assignments.

## Setup

No special setup is required other than to meet the preconditions of the transaction.

## Preconditions

* The **Experiment** exists and is Active.
* The **Experiment** is in the `Created` or `In Progress` state.
* The **Experiment Definition** mode of the **Experiment** is **Sub-Materials**.
* The new **Material** must meet the same preconditions as in [[user-guide-special-create-experiment]].
* Both the current and the new **Materials** must not have an `Experiment Lock Id` set.
* The new **Material** must be different from the current main **Material**.

## Sequence of Steps

### Step 1: Material

1. Select **Change Experiment Material** from the **Experiment**.
2. Select the new main **Material**.

    ![Wizard for the option to Change the Material](../images/experiment_change_material.png)

3. If the current **Sub-Material** assignment contains invalid entries for the new **Material**, the system removes them automatically and displays a warning.

### Step 2: Sub-Materials

1. Add, remove, or replace **Sub-Materials** as needed.
2. To speed up the assignment, use one of the available utilities:
    * **Clear All**
    * **Assign by Sub-Material Name**
    * **Assign by Container and Position**
    * **Assign Remaining Randomly**

    ![Wizard for the option to Change the Material step to select Submaterials](../images/experiment_change_material_submaterial.png)

3. Optionally, enter a comment.
4. Select **Change Material** to confirm the operation. The main **Material** history is updated accordingly.

!!! info "Previous Material Cleanup"
    When the main material is changed, the system clears the following properties of the previous material: `Experiment`, `Experiment Lock Id`, `Experiment Lock Type`, `Experiment Material Group Name`, and `Experiment Sub-Material Number`. It also removes future actions that reference that Material, including split and merge future action material lists.