My bag re-inflates overnight
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You sealed it, it was tight, and in the morning it's puffed back up. Here are the causes, in the order they actually occur.
1. The zip wasn't fully closed (most common)
If any part of the zip is open, the vacuum still works — the pump is strong enough to pull the bag tight against a small leak. But the moment you take the unit off, air creeps back in through the gap. It looks like a valve failure and it isn't.
Test: re-seal the same bag, press the zip hard along its full length with the sealing clip, and check it again in an hour. If it holds, the zip was the problem.
2. Something is sitting in the seal
Marinade, oil, a crumb, a sharp bone edge. Anything in the zip line holds it fractionally open. Wipe the inside of the zip dry before closing — particularly with raw meat and anything marinated.
3. The food is still releasing air or moisture
Warm food, freshly cooked rice, bread, and anything fermenting will off-gas inside the bag and puff it back up on their own. This is not a fault. Cool food to fridge temperature before sealing. Bread and baked goods will always re-expand a little — that's the crumb structure, not the seal.
4. The valve cap has come loose
Over a lot of uses, the small cap on the one-way valve can work loose or come off. It can usually be pressed back on. If it's lost or split, the bag won't hold a vacuum again and it's time to retire that bag.
What normal looks like
A correctly sealed bag of cold, non-gassing food should stay tight for weeks in the fridge and months in the freezer. If a bag that used to hold now doesn't, check the valve. If no bag has ever held, check the zip — it's the technique.
Bags not holding after all that? Email hello@sealit.com.au with your order number. Faulty bags get replaced.