Float texture is like a swiss knife. You can use it for many situations in Octane. One usage is that actually creates a gray scale value for the material channels. For example, if any channel has RGB color, this float value creates black for 0 and white for 1. The float here also works the same in Roughness, Bump, Normal, Opacity and Transmission channels.
Other usage is that you can define the float value to mix node as an amount factor. Any node has a parameters like "amount" or "texture" you can use float for them.
Let's take a look at a few usages of this node:
Create grey scale value from "Float" node for the material channel
Open the Node editor and prepare the setup as you see in the picture below. In this setup, you will create the gray scale values when you connect the Float Node to the diffuse channel of the parent material. The color in your diffuse channel is overridden by float texture. This is the simplest use.
Info: You can use any material channel that has "float" option
Create MIX BETWEEN gradIent TEXTURE NODE USING FLOAT
Open the Node editor and prepare the setup as you see in the picture below. In this setup, connect the Float Node to the input option of the Gradient texture node and enter any 2 color values from the gradient texture options. Then connect the gradient texture node to the diffuse channel of the parent material. As you can see in the picture below, when you play with float value, you will be mixing the gradient color values. You can easily use this setup in many scenarios. Also you can increase the number of gradient colors for more color mixes. We will explain the "Gradient Texture Node" later in detail.
USING FLOAT WITH THE MIX TEXTURE NODE
Open the Node editor and prepare the setup as you see in the picture below. In this setup, you can mix the Float Node into the amount slot of the Mix texture node and mix it between two different textures. We will not discuss the use of Mix texture and other nodes here. For a detailed description of these nodes, you can refer to the relevant sections.