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Packaging Supplies in the UK & Europe since 1953

Heat Sealing Polythene - Tips & Advice

Despite being very inexpensive, our standard range of heat sealers are fully up to most industrial applications. They are  "impulse" sealers which means the element only heats up for part of a second to weld the polythene. This sealing time can be adjusted to allow for differing thicknesses of polythene.

These sealers will seal Polythene and Polypropylene only - no other common plastic films.

They are available up to 500mm wide and will weld up to 2 layers of 1,000g (250 mic) film.

Beyond these parameters we can offer further ranges of sealers up to 5 feet wide and with double sealing elements, cable or chain operation, magnetic seal controls and programmed heating and cooling.

Sealers like these start at about £380.00 and get more expensive as you choose more sophistication.

The following FAQs should help to answer some of the most common queries...

Can I use my heat sealer to seal cellophane?

All of our cellophane bags are actually Polypropylene bags and as such CAN be heat-sealed on our impulse heat sealers. True Cellophane is not plastic, its actually paper so it cannot be heat sealed at all – It must be glued or crimped but none of our bags are true cellophane.

I have a "Packer" sealer purchased from you 2 years ago. Can I get spares for it?

Yes, we keep a full range of repair kits for sealing components but any repairs that are "below the case" would be subject to inspection and quotation. As the machines are pretty cheap in the first place such "below the case" repairs are usually uneconomical.

Our welds are coming out all puckered, what is wrong?

This is caused by too much heat - i.e. you need to turn down the dial until the puckering stops but the weld is still sound.

Our welds are bursting open when we fill the bag.

This is probably due to slightly insufficient heat. Try turning up the dial by just half to one point at a time until the welds hold properly.

After a few welds I can see a blackish build-up on the teflon over the sealing strip. What is this?

Its melted polythene! You may have your heat turned up just a bit high and this is causing excessive melting during the welding process. The excess melted polythene ends up on your teflon cover. Simply wipe it off and turn the heat down. Heat sealers should always be run at the minimum temperature at which a successful weld can be achieved.

What number on the dial do I need for 250g clear polythene?

It is not possible to say. The heat sealers all vary slightly and so does the polythene. One batch of polythene may weld nicely at number 3, and the next batch with exactly the same spec needs number 4. The machines, the polythene and the ambient working temperatures all vary.

I have an old Pifco heat sealer but it won’t work on your heavy duty bags. What is wrong?

These Pifco sealers were designed for domestic use only and I doubt they have the wattage to weld heavy duty polythene, so your comment doesn’t surprise me. I’m sorry to say that you’ll need to upgrade to a more industrial heat sealer to cope with heavy duty bags.

Can I get a machine that will weld a bag "standing up"?

Yes, most of the larger industrial heat sealers we supply can be mounted with the jaws operating in the vertical instead of horizontal. There are special stands that hold the machines ready to weld the top of a standing sack. You can even get conveyors to carry the sack to the sealer!

Heat Sealers

  • Impulse Heat Sealers are only hot for the very short weld cycle - a matter of a fraction of a second. This makes them safer and cheaper to use. These bag sealers are extremely fast and will weld up to 1000 gauge polythene
  • Semi automatic Heat Sealer Magnetic release impulse easy sealer with safety cutter. Push the arm down, the timed magnet release gives a consistent seal quality and speeds up your operation
  • Hand held lightweight constant Heat Sealers.  Light and robust hand held bag sealer in 2 styles, with adustable temperature control
  • PLAIN 150mm width x 2mm seal for PE/OPP/PVC.  25 watt
  • CRIMP 150mm x 15mm seal for OPP/foil. 50 watt
  • Large capacity Foot Operated Heat Sealers for industrial, warehousing and mail-order applications.

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