Milwaukee (My Home Town) Skyline - Black Gesso on Canvas with Pastel and Sandpaper

I am not sure if this is a final work or not - I am in the process of reviewing a technique used by Paul Balmer, an Australian artist.  He applies black paint to canvas and then draws in his image (using a cityscape) and then with a dremel (a power took that has a rotating disc head to sand or cut a surgace(he takes out the lines of his drawing leaving black canvas with the white canvas exposed from the action of the dremel on the canvas.  I don't have a dremel, so I used sandpaper to expose the white canvas.
Paul then paints a black layer over the cut canvas and then applies color to the under lying drawing that appears vaguely thru the second layer of black paint.
At this point I am stumped since I am not sure my sandpaper lines are deep enough to withstand an additional layer of black paint  - so that it shows thru slightly
As with a lot of my art work - I may consider it done, temporarily - and then just think about it periodically over the next weeks or months and decide if, in fact, it is done - or if I will do something else  to it.