The Silo ink cartridges look the same as the Epson cartridges--except for the labels, of course, and two plastic plugs on the top of the Silo cartridges. After installing a Silo cartridge, you must remove the colored plug before printing to allow air to flow into the cartridge. The other plug is clear and is used for refilling ink from optional 100ml bottles. This clear plug remains in place while printing.

The Silo cartridges snapped into place as expected, and the NX400 went through the cartridge charging cycle without incident. I did find that several cleanings from the Epson utility were necessary to get all of the nozzle test pattern to appear.

One other quirk I ran into: Every 150 pages or so, the NX400 would stop recognizing a cartridge in the middle of a print job. When this happened, I'd open up the printer, remove and replace the same cartridge, and the printer would go back to work. A few pages later, the printer would stop recognizing another cartridge, and I'd go through the same process. Once all had been reseated, the errors would stop. Unfortunately, the printer doesn't try and pick up where it left off on that interrupted print job; it just starts over. That may not a big deal when you're printing a text document, but it happened twice about two-thirds of the way through a letter-sized photo on Epson Premium Glossy photo paper. It took three sheets, at about 70 cents a sheet to print that single page.

The cartridge yield estimates used by most printer manufacturers are based on the number of times a sheet with five-percent coverage of all inks can be printed from a single cartridge. Instead of trying to duplicate the manufacturers' test files, I used a more real-world mix of images for this yield test, printing 50 sheets of black text from Microsoft Word followed by 20 sheets of a color PDF printed from preview--both at default "normal" quality settings. I then printed three letter-sized photos on Premium Glossy photo paper using Epson's Best Photo quality (a higher PHOTO RPM setting is available) from Photoshop and iPhoto and then started again with the text document. When the black cartridge ran out, I'd replace it and continue to run the color documents until the first color cartridge ran out.