The Multiply texture multiplies the values of texture or colors together in an overlay fashion. Figure 1 shows the results of a yellow RGB Spectrum node multiplied with a Marble texture node.
Figure 1: A yellow RGB Spectrum texture is multiplied against a Marble texture node, and the result is connected to an Octane material's DiffuseAmount of diffusion, or the reflection of light photons at different angles from an uneven or granular surface. Used for dull, non-reflecting materials or mesh emitters. channel