In Unreal Engine 5.7, Substrate becomes the default material system for new projects — a modern, physically based framework designed to replace the older legacy material model. Substrate represents surfaces as slabs of matter, giving artists more realistic control over how light interacts with materials, and making layering and blending more expressive.

Why would you switch between Substrate and Legacy?

• Visual fidelity & future-proofing: Substrate is the newer, more physically accurate system with advanced shading capabilities that the engine is moving toward as the long-term material workflow.
• Compatibility & flexibility: The legacy material system still exists for projects that need predictable, familiar behavior or that rely on workflows not yet fully supported by Substrate. Some artists find Substrate harder to use for certain effects (like traditional soft opacity), and the legacy system retains the old blend modes and behaviors many are used to. (Reddit)
• Control: Depending on your project needs — whether you want modern PBR layering or classic blend modes — you may prefer one over the other.
• Tutorials : Following tutorials based on the Pre-Substrate system.

Blend Modes aren’t the same in both systems

One of the biggest visible differences is how blend modes behave.

• In the legacy material system, you have the familiar dropdown options such as Opaque, Masked, Translucent, Additive, Modulate, Alpha Composite, etc. These are simple, intuitive, and used for traditional transparency and VFX effects.
• In Substrate, the material output structure and shading model are different, and you won’t see the same classic blend dropdowns. Material appearance and blending are driven by Substrate’s physically based slab framework, which changes how translucency and surface interaction are specified and controlled.

This means that if you need specific legacy blend modes (especially for UI, effects, or custom shaders), Substrate may not show those in the same way, and you may need to adjust material setup or switch back to the legacy path.

How to switch between Substrate and the old system

If you prefer to use the legacy material system (with the classic blend mode options):

1. Open Project Settings → Rendering.
2. Locate Substrate .
3. Disable Substrate materials.
4. Restart the Editor to apply the change.

After this, the engine will use the classic material path, and your materials will display the traditional blend mode controls again. Note that existing Substrate materials won’t automatically convert back — you may need to rebuild them in the legacy system if required.