I'm going to assume you're using the "Import Image" option and not the "Import Image to Layer" option. Either way, you're going to have to create a new layer over the layer of the imported image, because ArtRage will try to blend the colors of the image with those of the tools you're using. The problem you're really running into though, is from having imported the image directly. When one uses "Import Image", ArtRage sets the "Grain" of it's canvas to 0% smooth and transparent (so it's basically using the "Cell" preset it offers). It does this, so the lighting engine doesn't interfer with how the image is presented once imported (because using anything else would add an additional texture). But... You want the look of the Graph Paper with the feel of an actual paper not "glass" as you put it. So here's what you do...
Now you should be able to get a paper grain effect while you are drawing with the Felt Pen tool.
1 - Import your graph paper image using the "Import Image
" option (do not use the "Import Image to layer")
2 - Create a new layer to work on.
3 - Click the gray triangle (point 1 in the image below
) of the new layer to open the layer menu and select the "Edit Paper Settings
" (point 2
) option from the bottom.
4 - With the canvas panel open, select the "Basic Paper" preset (point 1 in the image below
) and then change it's "Opacity
" dial to read 0% (point 2)
5 - Click okay to except the changes.