Why Canon PG-275 and CL-276 Cartridges Need Vent Holes for Proper Ink Flow

Question:
In your video “No.1 Detailed Guide to Refill Canon PG-275 CL-276, PG-275XL & CL-276XL,” you mentioned the need for vent holes so the cartridge doesn’t create a vacuum during printing. But how do the original Canon cartridges work if their vent holes are covered with factory labels?
(Watch the video here)

Answer:

Now, to address your question—this is an excellent observation. It’s true that Canon’s stock cartridges like the PG-275, CL-276, PG-275XL, and CL-276XL appear to have their vent holes sealed by the factory label. However, what’s hidden beneath that label is a precisely designed vent channel system.

When you peel back the top label, you’ll notice a small pattern of grooves or holes molded into the cartridge’s plastic casing. These form air channels that allow a controlled exchange of air and pressure inside the ink reservoir. Canon covers these with a special semi-permeable adhesive label, which is designed to maintain a dust seal while still allowing air to pass through at a slow rate. This balance prevents ink from leaking during storage or transport, but also avoids creating a vacuum once the cartridge is in use.

When users refill these cartridges, they sometimes accidentally block the vent path with tape, glue, or an aftermarket label—causing ink starvation or uneven printing. This happens because the printhead relies on balanced internal pressure to draw ink through its nozzles. Without a functioning vent, air cannot enter as ink leaves, resulting in a vacuum that stops ink flow.

Here’s what you can do:

1. Gently peel off the factory label on top of the cartridge. You’ll find small vent channels or holes beneath it.

2. Avoid resealing these vents with tape or stickers after refilling.

3. If you’ve already refilled the cartridge, make sure those channels are open by inserting a small pin or needle into the vent hole to confirm it’s unobstructed.

4. You can also use a small piece of breathable tape (such as microporous medical tape) if you’re worried about dust but want airflow maintained.

In short, the “sealed” look is deceptive—Canon’s engineering uses hidden venting paths under the label that are critical for maintaining proper ink flow. Refilling users simply need to ensure those vents are unobstructed for reliable printing performance.

Addressing printer or cartridge issues can be tricky because of the hands-on nature of these repairs. Therefore, we’re unable to provide direct remote troubleshooting or one-on-one technical support. However, we offer in-person diagnostics and repairs at our local service facility (https://bchtechnologies.com/printer-repair-service). Due to high demand, we operate on a first-come, first-served basis, and there may be a waiting period before your printer can be serviced. Our repair program can address both complete printers and specific components, with clear guidance on the next steps.

That said, we know many customers prefer to troubleshoot on their own to save time and cost. We recommend starting with our YouTube channel’s homepage (https://youtube.com/@bchtechnologies) and using the search icon near the “About” tab to find tutorial videos for your exact cartridge or printer model. With hundreds of videos uploaded over the years, that’s the fastest way to locate the solution you need—and sometimes YouTube may also recommend helpful videos from other creators.

Thank you again for your thoughtful question and continued support of BCH Technologies. Your engagement helps us continue producing detailed guides and solutions for printer users worldwide.