Hey everyone,
I recently had a chance to test out the new Substrate material system by tossing one of my older projects into it - just to see if we could squeeze out any extra juice without too much effort.
**Turns out, I had to make a few tweaks to clean up some rendering issues. Most of them were probably due to my setup from the old Legacy material.
If you’re running into similar problems, this thread might help! I’ll share some quick fixes and tips that worked for me - hopefully, it’ll save you some time.
This video shows the result of converting to Substrate slabs with "1 SSSMFP"
Light set up : all ray traced shadows with 8 - 16 samples
- You can spot something is wrong when moving camera away from both groom and skin
TO FIX IT
- Uncheck “Scatter Scene Lighting” which is fine in the older version of the shader
This example is using native Hair BSDF from Substrate Slab
Another issue is about the “RED EARS”
To fix it :
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Make sure you’re using a SLAB setup - it’s essential to get the best out of Substrate’s subsurface scattering system.
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SSSMFP is the core parameter for Character’s SSS. >> Try setting it to a simple constant like “1” to start seeing results on skin or organic surfaces.
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Tweak the SSS Profile and experiment with the Scattering Distribution values to find your sweet spot.
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If you’re still not getting the effect you want, make sure your lights have ray tracing enabled this can make a big difference in how SSS behaves.
Wrapping up (using Substrate)
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Material Sensitivity Shift Substrate introduces slight changes in how materials behave >> especially SSS (Subsurface Scattering).➤ Expect to adjust values by 10–15% after migration for best results.
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Ray-Traced Rendering Looks Fantastic Substrate materials really shine under ray tracing—the visual boost is noticeable.
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Go Native for Hero Assets For high-quality hero assets, it’s best to build materials natively as Substrate slabs. This gives you full control and lets you take full advantage of Substrate’s power.
I believe we’ll have 2 options in upcoming UE update both Legacy and Substrate material in the same project settings.
I’m now really, really convinced to fully convert all my materials to native Substrate slabs. Even though it’s still in beta in 5.6, I’m all in to make the preparation and be fully moved when Substrate goes production-ready! 
Special thanks for SYUYA MUKAI to helping me figure this out
Thanks everyone to coming by.