From the ArtRage menu, choose 'Tools, Layer Options, Edit paper Settings'
Turn the Roughness radial to 0%, and paper will have no rendered grain.
Note that if you have an application that supports reading true 8 bit alpha from PNG images, you can set the opacity of your paper to 0%, then export your image as a PNG and you will get full alpha exported with the PNG. (This also works exporting the layer as a PSD file if you want to mess with it in Photoshop or something)
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"