So I attempted my first print on canvas paper because I wanted to solder to it. After printing 4 layers, I metered for conductivity and got nothing. I printed 2 more layers and still no conductivity. I'm wondering if there is a way to verify that both of my cartridges are firing properly. I see references to a nozzle test but dont know how to activate it. If my Ascorbic cartridge is not firing would the result on my paper still be dark grey / black or is that color an indication that the chemical reaction is happening?