Sometimes when people want that 'canvas' look, like a gallery wrapped canvas (love those! No framing required!) but need to paint or use their medium on a better or more appropriate surface here is what you do.......create your image on the appropriate foundation (for this she 'should' use a toothy watercolor paper IMO) AND THEN adhere it to a gallery wrapped canvas bigger in size to her image....that way she can have fun with the extra space and edges of the canvas and adhere her original to it and it doesn't need to be framed!
She can paint on the canvas first then just adhere her paper image to it! It works great!
And I recommend adhering with something like Liquitex Matt Medium gel (thick) for tooth to make it grab the canvas, then coat it with Liquitex Gloss medium gel (thick)........the medium goes opaque before it dries, so don't panic, it dries perfectly clear:)