Inside the Printer: The Anatomy of an HP Twin-Chamber Cartridge

Our twin-chamber cartridge is divided into two chambers. The back chamber is designed as an ink reservoir. The front chamber is filled with sponges. The sponge regulates ink flow to the outlet on the bottom. The two chambers are divided by a wall. The wall is sealed on the bottom for non-XL cartridges, such as a regular cartridge or startup cartridge. Therefore, the ink cannot flow to the front chamber. The back chamber is never used. If you can find a way to make a hole in the bottom of this wall, you will make an XL cartridge.

On the top, there is a T-shaped air intake, which leads to a prolonged air channel. The air channel connects to an air hole. When the cartridge is in use, the cartridge sucks air into it from the air hole. On top of the back chamber, there is a refill hole. For XL cartridges, HP injects ink into this hole and seal it with a plastic ball. Regular or startup cartridges do not use the refill hole. Although they still have this opening, they still have the plastic ball.

We cut open non-XL cartridges. We can see the opening at the bottom of the dividing wall, but the exact opening is placed on a regular cartridge. Therefore, we will only refill the front chamber for standard and startup cartridges.