Plastic Bag Sealing Machine

What seals readily

Polythene in its usual forms - LDPE and HDPE - is the easiest material there is. Almost any bench sealer will close it, and the only real decisions are thickness and width.

Polypropylene bags seal too, though they generally want a slightly different setting and are less forgiving if the time is too long. Most laminated pouches used for food have a sealant inner layer chosen precisely so they will close on machines like these.

What does not, or not reliably

Being clear about this saves wasted purchases, and it is the reason we ask for a sample rather than a description.

• Paper and paper-lined bags - there is nothing to melt. These are closed by stitching, gluing or a fold-and-tape.
• Foil without a sealant layer - the foil itself does not fuse.
• Woven sacks - PP woven bags for grain, cement and fertiliser are stitched or closed with a bag closer, not heat sealed, unless they carry a laminated liner.
• Some recycled and filler-heavy films - these can behave unpredictably from one batch to the next, which is worse for a production line than a film that simply does not seal.

Non-woven and jute-look bags

The bags handed out at exhibitions and shops that look like cloth are usually non-woven polypropylene. Some grades will heat seal and some will not, and it depends on the grade rather than the appearance.

If this is what you are packing, a sample is not optional - it is the only way to answer the question.

The rest of the decision

Once the material is settled, the choice is the same as anywhere else in this cluster: seal length longer than your widest bag, and a format that matches your daily count and whether the bag needs both hands.

Send the bag width measured flat, a sample or photograph of the material, and your daily count, and the recommendation follows from those three.

How to test a material before you commit

You do not need a machine to find out whether your bag will heat seal. There is a rough test anyone can do in five minutes, and it will tell you which conversation you are having.

Take two pieces of the bag material, lay them together, put a sheet of baking paper over them so nothing sticks to the iron, and press a household iron on a low setting across them for a couple of seconds. If they fuse into one and tear as a single piece when pulled, the material is thermoplastic and a sealing machine will close it. If they peel apart cleanly, or scorch without joining, it will not, or it needs far more heat than a bench machine gives.

It is not a substitute for sending a sample, and it will not tell you the right setting - an iron has none of the control a machine has. What it does is tell you within minutes whether you are shopping for a heat sealer at all, before anybody quotes you one.

If the test is ambiguous, that itself is useful information: ambiguous materials are exactly the ones we ask to see before quoting.