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Hair has particular unique qualities that need a dedicated material. The Corona Hair Material is physically accurate, and handles the unique highlights and transmission properties that hair requires, while still rendering quickly and giving you the ease of use in controlling the material that you expect from Corona. The hair material is mainly intended for creating human hair and animal fur, as it includes properties based on natural hair model (melanin pigment amount, anisotropic reflections, hair fiber caustics), however it can be as well used to render carpet strands, fuzzy fabrics, nylon strings, and other types of synthetic fibers. 

Corona supports the following plugins for generating hair geometry:

• Native 3ds Max Hair and Fur modifier 
• Ephere Ornatrix
• Hair Farm

Image Modified

Edith, by Markus Skibinski, Senior 3D-Artist, Stoll. von Gati GmbH | artstation.com/markus_s

Color

Level – Overall color multiplier.

Melanin – Controls the absorption inside hair fibers by setting the total amount of melanin pigment in hair. This sets the overall color of hair. A value of 0 (no pigment) leads to white hair, while value of 1 leads to completely black hair. The values between them give physically plausible human hair color.

Pheomelanin – Controls the relative amount of reddish pheomelanin pigment among the hair pigments and hence the hair redness. Value of 0 leads to 100% of eumelanin (brown pigment) and value of 1 leads to 100% of pheomelanin (reddish pigment causing ginger coloration).

Tint – Controls the absorption inside hair fibers. Setting this value to black leads to total absorption within the hair and hence black hair with only reflection. This value is not used on its own, it only tints the color calculated from (pheo)melanin. For natural human hair color, it is recommended to leave the tint at white, where it does not modify the color calculated from (pheo)melanin. It can, however, be used to simulate hair dyes, textile fibers, etc.

Transmission tint – Colors the light transmission through the hair fibers. For physically plausible results, it is recommended to keep this value as pure white.

Random. melanin – Controls the randomization of pigment amount between different hair strands. 0 means no randomization, 1 means completely random amount of hair pigment for each hair strand.

Reflection

Colored Reflection

Glossiness – Controls the glossiness of hair in the direction of the hair length. Value of 0 leads to very rough/diffuse hair, while value of 1 leads to the shiniest hair.

Tint – Color tint of the secondary (colored) reflection on the hair fibers. For physically plausible results, it is recommended to keep this value as pure white.

Colorless Reflection

Glossiness – Multiplier of glossiness parameter for the primary (colorless) reflection lobe. Increasing the value leads to sharper primary (colorless) reflection lobe compared to other lobes (colored reflection, transmission).

Tint – Color tint of the primary (colorless) reflection on the hair fibers. For physically plausible results, it is recommended to keep this value as pure white.

Softness (aniso) – Controls the overall softness of hair by changing the hair roughness along the hair width. Value of 0 leads to the roughest hair (high glossiness along hair width), while value of 1 leads to the softest hair.

Highlight shift – Shifts the highlights on the hair by changing the angle of scales on the hair fiber. Value of 0 leads to identical position of colorless and colored reflection highlights, increasing the value separates the highlights more by moving the colored reflection highlight.

Glint strength – Controls the strength of random glints (i.e. caustics caused by internal reflection within elliptical hair fibers). This effect makes random strands stand out from the rest, creating appearance of damaged hair. Value of 0 results in no random glints, value of 1 leads to the most apparent random glints. Increasing the glint strength leads to overall decrease in colored reflection.

IOR – Controls the index of refraction on hair surface. Value of 1.55 is recommended for physically plausible results. Increasing the value leads to more reflection on the hair.

Diffuse

Level – Diffuse component multiplier.

Color – Adds diffuse component to the hair. Clean hair does not have this component in reality, so it should be used only in very special cases (dirt in hair, non-hair objects, etc.).

Opacity

Level – Opacity multiplier.

Color – Controls the opacity of hair. Value of 0 leads to completely transparent hair, value of 1 leads to opaque hair.

Advanced

G-Buffer ID override (-1 = disabled) – If set to anything other than -1, this value overrides the 3ds Max gbuffer property. This allows you to set values outside of the 0-15 range permitted in the 3ds Max property.

GI simplification amount – When set to non-zero values, less precise global illumination is computed for this hair material. This leads to significantly less noise, but also more unrealistic results.

Female head model with hair, by Andrew Krivulya | https://artofcharly.artstation.com/ 

Melanin

Melanin lowered to 0 results in completely white hair. Higher values result in blonder hair. The higher the value, the darker the hair.

Pheomelanin

Increasing Pheomelanin results in a reddish hue visible in the hair.

Diffuse Color

Setting a diffuse color results in the hair appearing covered with a layer of paint. It can be used to add dust or dirt to hair. Lowering the diffuse level blends the diffuse color with the underlying natural hair color.

Random Melanin

Increasing melanin randomization results in various melanin levels in different hair strands.

Color Tint

Changing color tint gives the hair surface a subtle overall tint.

Transmission Tint

Transmission tint affects the color of the hair volume.

Colored Reflection Glossiness

Lower values of the colored reflection glossiness make the hair appear matted and less shiny while higher values make it look shiny and oily.

Colorless Reflection Glossiness

Increasing the colorless reflection glossiness makes the colorless reflections more focused so that the hair appears shinier.

Softness (Aniso)

Lowering the softness value makes the hair appear softer by reducing its reflection anisotropy.

Highlight Shift

Highlight shift set to 0 makes the colored and colorless reflections perfectly overlap with each other, merging them into a single reflection. Increasing this value moves the colored and colorless reflections apart.

Glint Strength

Glint strength affects the tiny variations of the hair structure. Higher values mean that the hair is more damaged. When this value is set to 0, the structure is uniform, so the hair appears soft and healthy.

IOR

The IOR value controls the overall hair reflectivity.

You can create a rainbow gradient from the roots to the tips by applying a gradient map set to WU coordinates:

Material setup:

You can use the checker map to vary hair diffuse color. Note that the texture is mapped on the surface of the base mesh and then distributed along hair strands based on that mapping:

Material setup: