V-Ray Sheer Curtain Material: A Guide to Translucent Fabric with 2-Sided

In Chaos documentation updated on 3 April 2026, V-Ray’s 2-Sided material is described as a way to create surfaces that let some light through, such as sheer curtains and lightweight fabrics. The guide covers using different materials on the front and back of the fabric and adjusting the Translucency value. Chaos’s pages do not specify a V-Ray version number, so the steps below are based on documentation for VRay2SidedMtl that does not identify a version.

1. Prepare the front material

Create a VRayMtl for the front face. In the Material Editor, follow Material/Map Browser > Materials > V-Ray > VRayMtl. Connect the fabric texture as a Bitmap to the material’s Diffuse map slot; set the texture tiling in the Coordinates section. The texture provides the color and pattern visible on the front of the fabric.

In Chaos’s example fabric setup, the Refract parameter is left at its default black value; the documentation says the fabric does not refract light. For subtle reflections, set Reflect to gray and set reflection Glossiness to 0.7 to soften them. Unlock the Fresnel IOR and reduce it from the default 1.6 to 1.3; in the example, this reduces the Fresnel reflection on the front face. Leave the remaining VRayMtl parameters at their defaults.

These values are a starting point shown by Chaos, not a formula that must be used for every fabric. The texture, lighting in the scene, and intended appearance can all affect the result. The core approach described in the documentation is to create restrained reflections without enabling refraction in the fabric.

2. Create the back face and connect it to the 2-Sided material

Prepare a second VRayMtl and use a different diffuse texture from the one on the front. In Chaos’s example, the other parameters of the back-face material are left at their defaults. This lets you control the surface character seen when light comes from behind the fabric.

Next, create a VRay2SidedMtl. In the material’s Parameters section, enable Back material and connect the VRayMtl materials you prepared to the Front and Back slots. Whether a face is treated as the front or back is determined by its polygon normals. If Back material is disabled, V-Ray applies the front material to both sides; enable it to use a different texture on the back.

Assigning a separate material to the back face is optional. According to Chaos’s documentation, if Back material is not used, the Front material is applied to both sides. This can simplify the setup when one texture is sufficient; if the two sides are meant to look different, assign separate materials.

3. Adjust Translucency for the scene

Translucency in VRay2SidedMtl determines the relative contribution of the front and back faces in the image, based on the camera’s position. In Chaos’s explanation, the default value of 0.5 makes both sides equally visible. As the value approaches 0.0, the camera-facing side has more influence; as it approaches 1.0, the back material becomes more visible.

Evaluate this setting not just by its numerical value, but also in relation to the lighting behind the fabric and the camera position. Start at 0.5 for a balanced view of both sides; try a darker Translucency color for a more opaque look or a lighter one for greater translucency. Chaos’s example uses medium gray in the final image.

The documentation also includes a Multiply by front diffuse option. When enabled, translucency is multiplied by the front material’s diffuse value; however, Chaos says this option is unavailable when the renderer is set to V-Ray GPU. In a GPU workflow, assess the available parameters instead of looking for this control.

4. Use and check the material in architectural visualization

This method is particularly useful in interior renders of windows where daylight comes through the curtain. Leaves and similar thin surfaces are also among the common use cases listed in the documentation. Preparing the front and back separately gives you control in scenes where the fabric should look different from each side; it is also possible to use a single material on both sides.

Chaos says the 2-Sided material works best on single-sided objects without shell geometry. Using shell geometry can significantly increase render times. Before rendering, check the curtain model’s surface structure and the scene’s lighting setup. The documentation does not provide hardware requirements, license pricing, or a compatibility table for specific V-Ray versions; do not make assumptions about these.

Common mistakes

• Expecting a different back-face texture without enabling Back material. When the option is disabled, both sides use the Front material.

• Treating the Translucency color as the only factor in the result. The value changes the visibility of the front and back; scene lighting and camera position also affect the image.

• Using refraction for fabric. Chaos’s example leaves the Refract color at its default black because the fabric does not refract light.

• Rendering a curtain with shell geometry without checking its surface structure. According to the documentation, the 2-Sided material can increase render times for this type of object.