A vacuum pack that goes loose in the freezer or on the shelf is called a leaker. Leakers are frustrating because the bag usually gets the blame, when the real cause is often somewhere else on the line. These are the five causes we see most often, and how to check for each one.
1. Contaminated seal area
Fat, blood, brine, crumbs or marinade on the inside of the bag mouth stop the two PE layers from fusing properly. The seal looks fine but has tiny channels running through it. Check by holding the seal up to light or pulling it apart: a good seal tears the film next to it, a weak one peels open cleanly. The fix is to fold the bag mouth back like a cuff while filling, or use a funnel or loading scoop so the product never touches the seal zone.
2. Wrong seal settings
Too little heat or time gives a weak seal that peels. Too much burns through the PE layer and leaves a thin, brittle line that cracks in the freezer. Seal bars also wear and their Teflon tape burns over time. Check the settings whenever you change bag gauge or supplier, and replace tape and seal wire on a schedule rather than waiting for problems.
3. Punctures from the product
Bones, shells, fins, frozen corners and even hard spices can push through film, especially during transport. Look for a small white mark or a ring of frost around one spot on a leaker. If you find it, go up one gauge, use a bone guard, or glaze or tray the product. A softer, tougher structure can also help more than extra thickness alone.
4. Flex cracks in transit
Film that folds and unfolds again and again, at a corner or where loose film flaps, can develop tiny cracks. This is common with bags much larger than the product, or with thin film at low temperature. The answer is a closer-fitting bag size, a structure with more nylon, and cartons that stop packs sliding around.
5. Machine and bag do not match
Smooth bags on an external nozzle sealer trap air. Bags that are too wide for the seal bar get a gap at one edge. Vacuum time that is too short leaves air inside even if the seal is perfect. Make sure the bag width fits the bar with a margin on both sides, the surface suits the machine, and the vacuum cycle is long enough for the product size.
Keep a simple log
Write down the bag batch, machine settings and leaker count for each shift. After a few weeks the numbers show clearly whether problems follow a bag batch, a machine or an operator.
How to find the real cause
Collect ten leakers and look at each one under good light. Mark where the leak is: on the seal, on the body near a sharp point, or on a fold. The pattern almost always points to one of the five causes above. If you send us photos or the packs themselves, PackEm can help read them and suggest a fix, whether that is a different bag or a change on the line.
