How to Make Candle Wax

In this tutorial we explore some of the properties of V-Ray Fast SSS2 and use it to create a candle wax material. The lesson guides you through the process of setting up a scene that emphasizes the sub-surface scattering properties of your assets and helps you understand the use of colors, phase function and scatter radius.

We start building our shader by assigning a V-Ray Fast SSS2 material to the candles and naming it Wax_MtlVRayFastSSS2Mtl1. Then set its Scale based on what we defined in the setup (e.g. for a 1:10 model, set a 0.1 scale). For our scene we leave it at 1.

Adjust the Index of refraction using an IOR table. We set it to 1.44. Feel free to experiment with different IOR values for different types of wax once you determine the other material attributes.

Next, make the material show strong forward scattering (somewhat like in the Cream or Potato presets) by changing its Phase function to 0.800.

Choose the Color mode and Single scatter based on the type of material you want to achieve: Sub-surface color and scatter radius in combination with Single Scatter modes: Simple or Raytraced (Solid) for relatively opaque materials like beeswax or paraffin, or Scatter coefficient and fog color with Raytraced (Refractive) for refractive materials like gel wax. The wax we are creating is opaque and with limited sub-surface scattering effect, so we use Color mode: Sub-surface color and scatter radius in combination with the faster Single scatter: Simple. 

For more accurate results you can use Raytraced (Solid), but in our scene the approximation renders almost the same and saves time.

Here is how the test render looks like.

VRayFastSSS2 material uses a number of color attributes to represent sub-surface scattering materials with complex color properties:

Keeping that in mind, let’s add a Sub-surface color. Choose a pale yellow with a tint of orange (e.g. RGB 227, 154, 60). That gives us the overall color, but notice how parts of the candles still appear gray.

To fix that, continue with the addition of a Scatter Color. Begin with one similar to the Sub-surface color and then tweak both if necessary. We settle for dull orange (RGB 197, 56, 10).

Scattering Depth

Adding colors gives us a nice warm look, but the material doesn’t seem to scatter enough light and the Scatter color isn’t showing as much as we want it to. One way to fix that would be to brighten the lights in the scene - check out the candle, located just in front of the well-lit back window. That way the material receives and respectively scatters more light, but other parts of the scene might become overexposed.

Let’s increase the Scatter radius value instead. The larger scatter radius gives us a deeper scattering effect with more rubbery looking material and less distinct surface details. Beware not to increase the Scatter radius too much or use the wrong Scale, otherwise the thinnest parts of the geometry become tinted in opposing colors or blown out. For this scene and candles model we choose a value of 3.3 cm.

Here is how the test render looks like.

To further enhance the scattering effect, we can enable the Scatter GI option¹. That increases the render time, but give us more accurate colors.

Here is how the test render with enabled Scatter GI option looks like.

Let’s continue with the specular properties of the material. Wax shows a lot of specular reflections, so we use the default values for Specular color - white and Specular amount - 1.0.

Depending on the finish of our candles, the Specular glossiness might differ a lot. If we were making rough handmade candles, we would choose smaller values, e.g. 0.3 or 0.4. For glossier look, let’s increase the Specular glossiness to 0.65.

The specular glossiness of the image on the left is set to 0.4, whereas the specular glossiness of the image on the right is set to 0.65.

Finally, you can choose to add a Bloom/Glare Lens effect to introduce some interesting light effects on the windows and candle flames.