Blue Opaque Polythene Mailers

Well made quality product with an Instant-Grab permanent adhesive seal on lip.

Blue polythene mailers are a popular choice for businesses and individuals who want to add a touch of colour and professionalism to their packaging. 

 

Code	Internal Dimensions (mm)			Thickness		Box Qty
1 (20M01)	229 x 318 + 50mm Lip			55 mu		1000
2 (20M02)	305 x 406 + 50mm Lip			55 mu		500
3(20M03)	330 x 483 + 50mm Lip			55 mu		500
4(20M04)	432 x 560 + 50mm Lip			55 mu		500
5(20M05)	483 x 737 + 50mm Lip			55 mu		250
6(20M06)	711 x 584 + 50mm Lip			70 mu		200

 

Tourer Branded Blue Opaque Polythene Mailers with High Grab Permanent Adhesive Peel and Seal Closure on Lip, are supplied in Tourer Branded Boxes.  Mailing bags are ideal for garments, soft goods or boxed products.

Key facts:

• Standard range of 6 sizes
• All made from strong opaque blue polythene with Instant-Grab permanent adhesive peel and seal closure on lip
• All mailers are printed with the Tourer brand name, code, warning notice and recycle logo, and come boxed in sturdy Tourer printed boxes.
• Proven quality product

 

Durable opaque polythene mailing pouch Supertough Permanent self-seal adhesive strip

Remember to update your PPI to Royal Mail new requirements!

Royal Mail now refuse any items with the old format PPI.  

 

 

Bags / Mailing Bags / Polythene Mailers - Blue

Blue Opaque Polythene Mailers

Blue opaque polythene mailers are a practical choice when you want a lightweight, weather-resistant outer pack that keeps the contents discreet in transit. The opaque film helps reduce show-through, while the bold colour makes parcels easy to identify during picking, packing, and returns processing. These mailers are commonly used for shipping soft goods (such as clothing), boxed items that don’t need rigid protection, and everyday ecommerce orders where speed and consistency matter.

Most polythene mailers are designed as an outer transit layer rather than a protective “crush-proof” pack. They excel at keeping items together, reducing scuffs, and providing a barrier against light rain and handling grime. For fragile products, pair a mailer with internal cushioning (for example, bubble wrap or paper void fill) or use a rigid carton first, then place the carton inside the mailer for a clean, tamper-evident outer finish.

Polythene Mailers — Helpful Guide

This guide explains the main features to look for in blue opaque mailing bags, how to choose the right size and thickness, and how to pack efficiently while reducing common shipping issues such as seal failures, trapped air, and incorrect sizing.

1) Peel-and-seal permanent adhesive mailers

The products in this category are blue opaque polythene mailers made with a permanent adhesive strip on the lip. A permanent seal is designed to bond strongly once closed, helping reduce accidental opening during transit. These mailers are typically used for one-way shipping where the bag is not intended to be reopened without visible damage.

• Blue Opaque Polythene Mailers 229 x 318mm + 50mm Lip (55mu) (20M01) — compact format for smaller apparel, accessories, and flat-packed items.
• Blue Opaque Polythene Mailers 305 x 406mm + 50mm Lip (55mu) (20M02) — a versatile mid-size option for folded garments, small boxed goods, and multi-item orders.
• Blue Opaque Polythene Mailers 330 x 483mm + 50mm Lip (55mu) (20M03) — useful when you need extra length for bulkier soft goods or larger bundles.
• Blue Opaque Polythene Mailers 432 x 560mm + 50mm Lip (55mu) (20M04) — larger format for coats, multiple garments, or bigger boxed items placed inside for a clean outer wrap.

Note on sizing: the “internal dimensions” describe the usable space inside the bag. The lip (for example, 50mm) is the flap area used for sealing and is not part of the internal packing length. When comparing sizes, focus on internal width and internal length first, then confirm the lip is sufficient for a reliable closure.

2) Opaque film for privacy and presentation

Opaque mailers are chosen when you want to reduce visibility of the contents and any internal packaging. This can help protect customer privacy and reduce the chance of items being targeted in transit. Opaque film also hides scuffs and internal void fill better than clear film, which can improve the appearance of parcels at delivery.

• For privacy: choose opaque film when shipping branded goods, personal items, or high-value products where discretion is preferred.
• For operational clarity: coloured mailers can help separate shipping streams (for example, standard vs. returns) or identify specific product lines during packing.

3) Thickness (micron) and what it means in practice

Mailers in this range are commonly specified by thickness in microns (often written as “mu”). Thickness influences puncture resistance, tear resistance, and how the bag behaves when pulled tight around corners. A thicker film generally offers improved durability, especially for items with sharper edges or when parcels may be dragged across conveyor surfaces.

• For soft goods: a standard thickness is usually sufficient, provided there are no sharp components (buckles, metal parts, rigid corners).
• For boxed items inside the mailer: consider the risk of corner wear. If the box corners are sharp, add corner protection or a light internal wrap to reduce abrasion.
• For mixed orders: if you ship a variety of items, standardising on one or two sizes and a dependable thickness can reduce packing errors and speed up fulfilment.

Practical tip: thickness alone doesn’t guarantee performance. Seal quality, film formulation, and correct packing technique (removing excess air and avoiding overstuffing) are equally important for preventing splits and seal creep.

Case Study: Reducing “bag split” and “seal lift” incidents

A small ecommerce operation shipping apparel and accessories noticed an increase in customer reports of parcels arriving with torn corners or partially opened flaps. The root causes were not the mailers themselves, but inconsistent packing habits: overfilling bags, leaving trapped air that expanded under pressure, and sealing over dusty or creased film.

After standardising their process, issues dropped significantly. The changes were simple:

• They matched bag size to the order profile (avoiding tight fits that stress seams).
• They flattened the contents and pressed out excess air before sealing.
• They ensured the sealing area was clean, smooth, and not folded.
• They applied firm pressure along the full width of the adhesive strip, especially at the edges.

The result was fewer transit failures, faster packing, and more consistent parcel presentation—without changing carriers or adding complex materials.

How to choose the correct blue polythene mailer

Step 1: Measure the packed item (not the product)

Measure the item as it will be shipped, including any inner bag, tissue, or protective wrap. For clothing, measure the folded bundle. For boxed goods, measure the box. Use the largest dimension in each direction (width and length) and allow extra space so the mailer isn’t under tension.

Step 2: Choose width first, then length

Width is usually the limiting factor. If the item is too wide, the bag will stretch and stress the side seams. Once width is correct, select a length that allows the contents to sit below the sealing line with enough clearance to fold the lip down flat.

Step 3: Consider corners, edges, and puncture risk

Mailers perform best with soft or rounded contents. If you’re shipping items with corners (boxed products, books, hard cases), reduce abrasion by adding a thin internal wrap or placing the item in a secondary inner bag. This helps prevent corner wear and reduces the chance of punctures during handling.

Step 4: Think about returns and opening method

Permanent adhesive mailers are intended to stay closed. If your returns process requires customers to reseal the same bag, consider including a separate returns bag or a resealable inner pack. If customers will open the parcel with scissors, advise them to cut carefully along the top edge to avoid damaging the contents.

Packing tips for stronger seals and cleaner parcels

• Remove excess air: trapped air increases parcel volume and can stress seams when compressed in transit.
• Seal on a flat surface: align the lip evenly and press firmly across the full width, paying attention to the corners.
• Avoid sealing over creases: folds and wrinkles can create channels where the adhesive doesn’t fully bond.
• Keep the adhesive area clean: dust, fibres, and moisture reduce bond strength.
• Don’t overfill: if the contents sit too close to the seal line, the flap may lift under load.

Storage, handling, and environmental considerations

To maintain consistent sealing performance, store mailers in a clean, dry area away from direct sunlight and heat sources. Excess heat can soften adhesives and cause blocking (bags sticking together), while cold conditions can make film less flexible. If mailers are stored in a cold warehouse, allow them to acclimatise before use so the film and adhesive perform as expected.

For waste handling, polythene mailers are typically made from plastic film that may be recyclable where soft-plastics collection exists. Always follow local guidance for film recycling and disposal. If you include additional materials (labels, tapes, paper inserts), consider how these affect recyclability and whether they should be separated.

Common mistakes (and how to avoid them)

• Choosing a bag that is too small: leads to stretched seams and corner splits. Size up if the item is close to the internal width.
• Sealing too close to the contents: leaves no flat area for the adhesive to bond. Ensure the contents sit below the seal line.
• Not applying pressure along the full seal: especially at the edges, where openings often start.
• Using mailers as the only protection for fragile items: add internal cushioning or use a carton first.

Frequently asked questions