This week is my first attempt at refilling . I'm doing the Canon # 226 CMY cartridges with Precision Colors Gray inkset . I drilled a 1/8 inch hole on top. Then I went to my bathroom sink where I turned on my Water Pik dental appliance at lowest setting and placed the nozzel in the re-fill hole for 80 seconds after which the water ran out clear. I then went to my garage and turned on my air compressor. I placed the nozzel of the air hose proximal to the re-fill hole but not jam up gainst it . The water blew out through the sponge hole in three seconds with no damage done. I put the cartridges aside to dry for a day. Then I re-filled them with the new gray inks which are not contaminated with the colors. Now I'm awaiting an error message to pop-up on my screen telling me this procedure is disallowed .