Category Archives: Polythene News

Recycling – What are we doing for the environment and what can we help you to do?

What are we doing for the environment and what can we help you to do?

STM Packaging Group recycles all of its process and office waste (and always has done!)

Our own process waste polythene, plus material returned from our customers, local companies, and individuals goes to a specialist reprocessor, Chase Plastics, a key partner to our Group. They reprocess the clear and mixed coloured waste separately and return the recycled polymer granules to us. Due to Chase Plastic’s unique double clean process, this material is returned with very low odour levels. We then make new products with those polymer granules – recycled clear bags, grey mailers and tube film for lots of suitable applications.

We also recycle all of our waste boxes and office paper through the usual paper recycling channels. In addition, we donate our broken pallets, waste reel cores, and any other wood waste to members of our staff with multi fuel burners to generate free and carbon neutral heat for their homes.

“But how can polythene be a good option?”

All polythene (LDPE) is recyclable. This is a key question we are being asked by customers and end users alike. To help to explain this, we have advanced plans in place to add a ‘recyclable’ or ‘recycled’ message to all of our stock mailing bags to increase public awareness and to help improve recycling levels of the product from the domestic environment. We can also offer a wide range of recycled films. Please ask one of our expert advisors if this is of interest to you and your customers.

To recycle all of your polythene products, you can return it to STM Packaging for reprocessing. If this is not convenient, you can put all polythene products into the supermarket carrier bag recycling stations and they will recycle them for you.

carrier bag recycling stations

reduce reuse recycle symbolAn exciting new project!

STM Packaging is working on a new project – we are trialling a film made from corn starch which is 100% biodegradable – we will let you know as soon as this product is available!

We believe it is great to see so many new initiatives being developed to address the effects of plastics in the environment. One eye-catching scheme in the media recently was RPC bpi, a leading plastics company, recycling very low grade polythene waste into polymer granules to be used in road building. What a fabulous use of the material where it can never litter or get into the wider environment while saving the natural resources of making bitumen.

If you have any further questions for us on this hot topic, please don’t be shy – ask us, and we are sure we can help to assure you and your supply chain of the credentials of using an ethical polythene company!

Daisy and splatter printed mailing bags

Our new Daisy and Splatter designs are here!

We’ve added two new designs to our growing divinely different® printed mailing bags range – Daisy and Splatter!

Here at Sefton Transmail we recognise just how popular our divinely different® printed mailing bags are for our customers that want to make an impact with their packaging but don’t want the additional cost of custom bags. We loved both of these designs so much that we decided to release both at once – a Sefton Transmail first!:


Our retro Daisy design is guaranteed to catch the eye. We designed
this in four different colour variants so you can mix and match.

Daisy printed mailing bags
Turquoise daisy printed mailing bag
pink daisy printed mailing bag
purple daisy printed mailing bag
purple daisy printed mailing bag
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Our Splatter design comes in two colours – blue and black. This bold design is sure to grab attention!

black and blue splatter printed mailing bags
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With our new designs you can expect the same great quality as our other products. Each bag is sure to have the following:

  • A strong, permanent ‘peel and seal’ adhesive flap.
  • Super tough side seams, manufactured using 50micron co-extruded film.
  • Opaque and weatherproof so the contents stay safe and secure.
  • Eye-catching designs in vibrant colours.
  • A blank address area suitable for pen or labels.

Our Daisy and Splatter printed mailing bags are available in the most popular mailing bag sizes:

  • 162mm x 230mm + 40mm lip for your C5 sized items
  • 250mm x 350mm + 50mm lip for your C4 or slightly oversized C4 items
  • 330mm x 440mm + 50mm lip for C3 sizes items.

Please don’t hesitate to contact our experienced sales team today to discuss products or to place an order for next day delivery.

Hot pink polka dot printed mailing bags

New hot pink polka dot printed mailing bags

Please give a warm welcome to our new hot pink polka dot colour

Hot pink polka dot printed mailing bagsHere at Sefton Transmail we wanted to banish the January blues with a brand new hot pink polka dot design in our divinely different® range. If you have previously purchased our divinely different® star printed mailing bags in “Neon-light” pink you may already recognise the colour, it’s so popular and we loved the colour so much that we couldn’t pass up the opportunity to add it to the polka dot range!

The polka dot range has gone from strength to strength since its creation a couple of years ago. At the beginning we only started with 3 colours (pink, green & blue) and now with the addition of Hot Pink we have grown to a range of 10 popular colours.

Still to this day, we are the only UK manufacture of our divinely different polka dot mailing bags and you can expect the following while using them:

  •  A strong, permanent ‘peel and seal’ adhesive flap.
  • Super tough side seams, manufactured using 50micron co-extruded film.
  • Opaque and weatherproof so the contents stay safe and secure.
  • Eye-catching designs in vibrant colours.
  • A blank address area suitable for pen or labels.

Our Hot Pink polka dot mailing bags are available in the most popular mailing bag sizes:

  • 162mm x 230mm + 40mm lip for you C5 sized items (coming soon)
  • 250mm x 350mm + 40mm lip for your C4 or slightly oversized C4 items (coming soon)
  • 330mm x 440mm + 40mm lip for C3 sizes items.

Please don’t hesitate to contact our experienced sales team today to discuss products or to place an order for next day delivery.

A collage image showing how SeftonTransmail make an effort to keep the environment better using polythene.

How polythene is environmentally friendly

Everyone at Sefton Transmail was very excited about the launch of The New Fiver. As manufacturers of polythene we know what a bad rap plastic products get, but finally the world is starting to see how plastic and polythene products can benefit the environment! Even the Bank of England agrees that it has more benefits than paper with their switch to polymer bank notes.

How is polythene safer?

The New Fiver has several security features which make it even harder to counterfeit. These include the see-through window (not possible with paper) and the foil Elizabeth Tower which is gold on the front of the note and silver on the back.

Although it’s not necessary for polythene bags to have such high-tech security features your products are safer in a polythene bag because they are protected from elements, and if you chose to have a custom mailing bag you can have double glue lines & tamper evident seals. We also manufacturer cash bags which can be sequentially numbered to add an extra level of security. To find out more about these features follow this link to our custom mailing bags page.

How is polythene cleaner?

Polymer notes are better for the environment compared to the paper notes we’re accustomed to. This is because they last longer and so we have to print fewer notes, which means less energy is used in manufacturing and cash transportation. When a polymer note has reached the end of its life it will be recycled into new plastic products.

This is the case for polythene bags as well, they have a longer shelf life than paper and are more resilient to the elements. When they come to the end of their life we recycle then into a polymer blend which can then be extruded. We also offer a large range of products made from recycled polythene. Polythene envelopes allow a greater weight of insert to be housed in a water-proof and secure way. The weight of paper required to meet similar strength criteria is very much higher which causes additional costs and waste in the distribution chain. In addition, on a like-for-like weight basis, paper uses 100% more power to manufacture. If you are interested in the environment points of polythene checkout our environment page.

How is polythene stronger?

Each new polymer note is expected to last at least 2.5 times longer than the current paper notes. This is because polymer is stronger than paper so the notes can better withstand being repeatedly folded into wallets or scrunched up into pockets making them resistant to everyday wear and tear. They are also waterproof which in turn means they can be wiped.

This emphasizes the points made above about how polythene is more durable than paper. The same is true for polythene bags, they are much harder to tear and can withstand being thrown about by couriers as it’s incredibly durable.

Sefton Transmail Manufacturing Floor

Custom Polythene Bags Minimum Quantities Explained

One of the things we find here at Sefton Transmail is that people get frustrated by minimum order quantities on custom polythene bags, so we thought we would try and shed some light on the subject.

Firstly, we don’t like minimum order quantities on custom polythene bags either but sometimes they’re necessary. We thought we’d speak to our expert sales and production teams to find out more about the reasoning behind it.

The biggest issue is the cost of low quantities. We have to factor in operators, set up, waste, film, and ink (if printed) – all of which increase the cost as the quantities get lower. But don’t fret – if the high cost of low quantity custom mailing bags is your problem, then we can help. We’ve created the divinely different range® especially for people that want to make an impact without the additional cost of custom print. It’s a range of pre-printed stock polybags, available in 4 designs in the 3 most popular sizes. For more information and images of the designs we currently have, check out the divinely different® range.

However, this range isn’t for everyone. You may need a special size or you need to have your company logo, or you may even require a plain or clear bag.  For these occasions our minimum order quantity for a bespoke / custom polybag is 1,000. The main reason for this is machine set up. Although we strive to be as flexible as possible for our customers, we manufacture in-house and if we were to set up and run a quantity as low as 250 polybags this would produce about 400% waste. This is not cost effective, so you may as well get your money’s worth and get the thousand.

Unfortunately, there are other factors that can make the minimum order quantity higher. One culprit is whether we have the polythene reel film in stock to make your sized mailing bag. We aim to hold a wide range of polythene reel film in stock but these reels are enormous. Furthermore, as the name custom polythene bags suggests, it could be any size so we can’t always cater for everyone with stock film. With so many options available it’s hard to stock all types of film. You could want clear bags, recycled bags, oxo-degradable bags, grey bags or even a special coloured film bag. Holding enough types of polythene reel film to handle all those different requirements simply isn’t possible for us.

That is one of the great things about having a sister company like Shirlplass! They specialise in polythene reel film, and being our sister company they also share our dislike for minimum order quantity restraints and do everything they can to help us help you. We can order quantities as low as 100kg of any sized film from Shirlplass, meaning we can lower the minimum order quantity quite a considerable amount.

We hope you have found this article helpful. If you have any other questions visit our product page regarding custom mailing bags to see all the options available. Alternatively you can get in contact through the enquiry from on the contact us page and one of our expert sales team will answer any queries.

Polythene film reels clear and co-extruded

What is polythene?

Many of us use polythene every day, sometimes without even realising, but few of us know how it is made or how it was discovered.

Sefton Transmail are experts in polythene but we understand not everybody is. We’ve put together a list of some of the highlights and little known facts about polythene, its beginnings, production and usage.


  • Polythene is regarded as the most common plastic in use today, both commercially and industrially.
  • Polythene is completely waterproof.
  • Despite being a light weight material, polythene is incredibly durable, strong and flexible.
  • Polyethylene (as it is scientifically known) was first discovered by accident in 1898 by a German chemist called Hans von Pechmann. His colleagues Eugen Bamberger and Friedrich Tschirner termed the white, waxy substance as polymethylene.
  • In 1933 Eric Fawcett and Reginald Gibson also accidently created the substance at the ICI works in Northwich, their attempts to replicate the ‘accident’ proved difficult.
  • In 1935 Michael Perrin, another ICI chemist developed a process that marked the basis for industrial polyethylene production, which then began in 1939.
  • Large scale commercial production began in 1944 by Bakelite Corporation and Du Pont, under licence from ICI.
  • The process of creating polyethylene begins when ethylene is acquired from natural gas or petroleum. This is then combined with oxygen in a polymerisation process, which in turn allows for the formation of long chain polymer molecules, the Polyethylene is made.
  • There are two main groups of polythene, High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE). HDPE is mainly used in rigid, high strength products such as containers and bottles. LDPE is most commonly used for the vast majority of products that Sefton Transmail manufactures: mailing bags, polythene envelopes and polythene wrap. In addition to these two main groups there is also Medium Density Polyethylene (MDPE), mostly used to make pipes and fittings as well as some carrier bags and films.
  • Approximately 80 million metric tons of polyethylene is produced each year.
  • In 2009 the estimated global market for LDPE was in the region of £13.2 billion.
  • Global consumption of HDPE reached over 30 million tonnes in 2007.
  • The melting point of LDPE is 105oC to 115oC (221oF to 239oF), whilst HDPE is 120oC to 180oC (248oF to 356oF).
  • For the scientifically minded, the graphic below shows the polymerisation process, from ethylene to polyethylene.

ethylene to polyethylene chartPolthene created from polymer pellets

Here is a selection of just some of the items that can be made using polythene:

Grey, Recycled, Made again, Green, Environmentally Friendly, Cheap, Mailing Bags, Cheap


Grey mailing bags – we offer a vast selection of stock sizes and customisable options. We also stock grey mailing bags that are made from recycled polythene.



Bright, Coloured, Polythene, Opaque, Co-extruded, Polythene, STM


Spectrum mailing bags – maximise impact when sending out goods with our coloured co-extruded range.




Polka dot printed mailing bags



Our divinely different range – a stylish way to send out all of your packages, this range consists of a variety of designs printed on white co-extruded polythene.



parking charge notices



Parking charge notices – these clear polythene printed notices are carefully designed to be waterproof, durable and leave no sticky residue.




Greeting Card, Polythene bags, Cast Polypropylene, CPP, Cello Bags, Transparent, Re-sealable


Polypropylene bags – these “glass clear” bags are great for displaying cards, envelopes and packing clothing items.




Grip seal polythene bags


Grip seal bags – these clear bags are ideal for holding spare parts, components and a huge range of other items.





For further information on any of the items, or for a quote, contact our team of polythene experts.

divinely different polka dot printed mailing bags

Newest colours of polka dot mailing bags

divinely different, printed mailing bag, coral, blueWe are excited to announce the newest printed mailing bag colours to our popular divinely different polka dot range – Royal Blue and Coral!

These new colours add to our ever growing polka dot range which now including the following colours – Blue, Green, Pink, Silver, Gold, Red and Purple

As part of the STM Packaging Group we manufacture our own range of printed mail bags in a variety of styles, colours and sizes.

Our Polka Dot Mailing Bags have received a huge response from customers, we know that you all love using them, packing with them and of course receiving them on the doormat or when the postman knocks.

All of divinely different mailing bags feature a strong, permanent ‘peel and seal’ adhesive flap and super tough side seams to ensure that what goes in the bag, stays in the bag!

For more information give our team a call on 01603 404217 or visit our divinely different mailing bag page

Don’t be stuck doing the same as everyone else – Be Divinely Different!

Polythene, environment, recycling

Why Choose Polythene

Polythene is an incredibly versatile material and it’s used all over the world as a protective product, wrapper or container.

The impending 5p charge for supermarket carrier bags has fuelled the publicity surrounding the use of polythene and its environmental impacts. We want to show you the benefits of polythene and why you should choose it.

The Environment:Why choose polythene
  • When disposed of correctly it can be easily recycled and made into a wide range of other products.
  • Polythene is made using a by-product of the oil refining process, and uses less energy than paper to convert the raw polymer pellets into a usable form.
  • The recycling process is also low on energy use as polythene only needs to be melted and reformed.
  • Paper is a common alternative to polythene. The use of paper is not the environmental solution that many people think it is. It is estimated that to create 1 ton of copier paper using the Kraft pulping process around 24 trees are required*.
  • Similar figures could be used to estimate the amount of trees required for the manufacture of paper envelopes.
  • In addition to the amount of raw material, there’s also a significant amount of energy and chemicals required in the manufacturing process of paper and also recycled paper.

When choosing between using paper packaging and polythene packaging, consider the source of the raw material, the energy required to produce it and the ease of which it can be recycled – it’s easy to see why polythene is such a popular choice!

We are very environmentally conscious and we know that many of our customer are too, for further information visit our environment page.

Quality and durability:

As well as the environmental impact there are also other things to consider, such as quality and durability. Research and development of improved polythene materials allows us to provide protection whether you are looking to keep goods in a warehouse, transferring pallets during transit or posting small items direct to customers. Polythene will ensure your goods arrive safely whilst providing a cost effective solution when compared to paper envelopes and boxes.

Durability and High Strength: Polythene’s properties of high strength, versatility and durability makes it the ideal material to use when protecting most goods, regardless of size or shape.

Waterproof: With polythene you can be assured that however bad the weather your customers will receive their products without any water damage. Common alternatives to polythene, such as cardboard boxes and paper envelopes, do not protect against excessive moisture, as a result water can disintegrate the packaging and potentially damage the products.

Rip Resistance: A major concern when despatching goods with a courier or sending in the post is the quality of the packaging and the condition they will arrive when delivered. Sometimes items sent out in boxes can have damaged sides with some of the contents of the box missing. However, unlike paper, polythene is rip resistant and won’t tear easily, this means that when sending out products the packaging will still securely hold the contents.

Tamper Evident: Most of our mailing bags and envelopes feature a permanent tamper proof peel and seal strip. This creates a secure seal to send a wide range of valuable products and documents safe in knowledge that you can tell if the envelope has been opened or tampered with.

Contact us today to find out how we can help you find the right polythene packaging for your products.

Polythene mailing bag size guide

Mailing Bag Size Guide

Grey mailing bag sizeDue to the different shapes, sizes and varieties of items being packed, it’s easy to become confused when choosing the right mailing bag size for your needs!

We all know that mailing bags have become one of the most important items of packaging for retailers. With so many sizes available it’s hard to know what mailing bag size you require, so we’ve created a handy size guide. As a company we continue to review the sizes we provide from stock to ensure we can always provide a great range of options.

Size guide:
Size (MM) Suitable For
120 x 160 + 35 Flap Mobile phone covers, items of jewellery
162 x 230 + 40 Flap A5 documents, DVDs / Blu-Rays, video games
230 x 310 + 40 Flap A4 documents, books, magazines
250 x 350 + 40 Flap Smaller items of clothing (e.g. T shirts)
305 x 405 + 40 Flap Medium items of clothing (e.g. sweatshirts)
320 x 440 + 40 Flap Shoe box, large items of clothing (e.g. hoodies, jackets)
350 x 500 + 50 Flap A4 lever arch file, box file
425 x 600 + 50 Flap Extra large items of clothing (e.g. coats)
550 x 750 + 50 Flap Blankets, cushions
600 x 900 + 50 Flap A1 flip chart pad
850 x 1050 + 50 Flap Extremely large boxed items

All of these sizes are available in our original grey and recycled made again® mailing bag ranges. The most popular sizes are also available in our Spectrum® coloured mailing bags and our new divinely different® printed range. All of these items have been tested and they all fit in the mailing bag size suggested; however, always measure the size of the item first! If we can’t meet your requirements with our stock bags we also offer custom mailing bag options.

If you are still unsure what is the best size contact us today, our team of experts can help you find the right solution!