# Blender 3D: Noob to Pro/Subsurface scattering

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Real-life materials which may look opaque are often not perfectly
opaque: light may penetrate a little way into the surface before
bouncing off. This is noticeable as a subtle softening and colouring of
the edges of shadows on the object. This effect is known as *subsurface
scattering* (commonly abbreviated
"SSS").

![](Blender267MaterialSSSSettings.png "Blender267MaterialSSSSettings.png")
Open a new default Blender document. Select the default cube. Go to the
Material
![](Blender255MaterialContextButton.png "Blender255MaterialContextButton.png")
context in the Properties window. Look for the Subsurface Scattering
panel. Check the box at the top to enable it for the cube's material.

!Subsurface scattering with default settings, before and
after
Compare how the cube looks with and without SSS enabled: see how the
edge of the shadow becomes a little bit fuzzy? This is simulating the
effect when the light penetrates a little way into the material,
emerging just within the edges of the shadow, making them that little
bit lighter.

Note the following settings in the SSS panel:

-   The *Scale* controls how the overall size of the effect relates to
    the size of the object. If you size your object so that 1 BU is
    equivalent to 1 metre, then the default scale of 0.1 should produce
    a realistic effect.
-   The colour swatch causes the scattered light to take on the
    specified colour.
-   The RGB Radius values govern how far the red, green and blue
    components of the light penetrate into the material before being
    scattered. These are relative values, all subject to the overall
    Scale factor.

!Higher red scattering
radius
For example, this is what happens when the red radius is increased to
10, leaving the green and blue radii and the actual scattering colour
unchanged: this causes the red light to travel further, tinting the
interior of the shadow red and the adjacent area the opposite
colour---blue-green. This is similar to what happens with human skin, as
the light scatters through the blood vessels underneath.

![](Blender267MaterialSSSPresets.png "Blender267MaterialSSSPresets.png")
Try the various options in the Presets menu: how convincing do they
look? Of course, they may look better if you apply them to a model that
is supposed to look like the actual material.

