If a vacuum pouch won't seal properly in a chamber machine, the cause is almost always one of four things: something on the seal area, the pouch not lying flat, the seal time set wrong, or a worn seal bar. Work through them in that order. The first two cost nothing to fix, so start there. If none of them is it, check you've got the right pouch for the machine.
What does a good seal look like?
A clean, even band across the full width of the pouch, clear or slightly frosted, with no gaps, bubbles or creases running through it. Pull gently either side of it and the film should stretch before the seal gives. If yours looks like that and the pack still goes loose, the seal isn't the problem. Read the guide to packs losing vacuum instead.
1. Is there anything on the seal area?
Fat, blood, brine, marinade, crumbs of cheese. Any of them across the seal line stops the two layers of film fusing. The seal looks fine and leaks within a day.
- Fold the top 50mm of the pouch outward like a cuff before the product goes in, then fold it back.
- Pack product cold from the chiller. Warm meat pushes more liquid out under vacuum.
- Wipe the inside of the mouth with clean paper if anything's got on it.
- For very wet product, lay the pouch so the open end sits slightly higher than the product, using the filler plates if your machine has them.
2. Is the pouch lying flat on the bar?
A crease across the seal bar becomes a channel in the seal. Smooth the open end flat with your hand before you close the lid, with the pouch square to the bar and the open end just past it. Check the width too: the pouch has to be at least 20mm narrower than the seal bar or the corners fold up. A 300mm bar takes pouches up to 280mm wide. If you're squeezing a 300mm pouch onto it, that's the problem.
3. Is the seal time right for the film?
Chamber machines let you set how long the bar heats. Too short and the film doesn't fuse. Too long and it melts thin, goes brittle or burns through.
| What you see |
Likely cause |
Fix |
| Seal peels apart easily |
Seal time too short |
Increase a step at a time |
| Seal is brown, brittle or holed |
Seal time too long |
Reduce a step at a time |
| Good in the middle, weak at one end |
Uneven bar or worn tape |
Check the bar (step 4) |
| Creases through the seal |
Pouch not flat, or too wide |
Re-lay the pouch, check width |
If you've just switched gauge, expect to adjust. Our standard 65 micron pouches need less heat than the 130 micron. Your machine's manual gives a starting setting.
4. Is the seal bar worn?
The bar is covered in a heat-resistant PTFE tape, and on many machines there's a silicone strip on the lid that presses down on it. Both wear. Signs: a seal that's weak in the same spot every time, a mark in the seal that matches a nick in the tape, or a lid strip that's flattened or cracked. Tape and strips are consumables. Your machine dealer or service engineer will have them for your model.
5. Is it the right pouch?
Our pouches are smooth PA/PE film made for chamber machines. They seal in Henkelman, Multivac, Orved, Boss and the other brands on our compatibility page. They won't work in a FoodSaver or any other edge sealer, because those need an embossed bag to draw the air out. The FoodSaver guide explains why, and the embossed vs smooth guide covers the other direction.
Still not sealing?
If you've been through all five and it's still failing, the machine needs a service engineer. A failing heating element or a timer fault won't show up any other way.
Want to rule the pouch out? Ask for a free sample pack, tell us your machine make and model, and test a few on a known-good setting.
