Depending on the scene lighting, painting and previewing a specular map can be difficult as the specular effect is somewhat transparent as you paint.
To preview and edit a specular map
- Temporarily move the paint layer from the Specular channel to the Diffuse channel.
(If there is currently no Diffuse channel, right-click the layer instead and select Move Selected To > Diffuse to create it.)
This lets you view and the specular effect more easily.
- When finished editing, drag the layer back to the Specular channel.
(If there is currently no Specular channel, right-click the layer instead and select Move Selected To > Specular to recreate it.)