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Everything You Need to Know About Custom Poly Mailers - Package N' Go

Everything You Need to Know About Custom Poly Mailers


Table of Contents

Chapter 1: Understanding poly mailers


1.1 What is a poly mailer?


Poly mailers, commonly known as plastic shipping bags or poly bags, are one of the most popular packing options on the market right now. They are ideal for shipping a variety of items because of their light weight, toughness, and waterproofness. Moreover, their self-sealing capability removes the requirement for additional tape during the packaging process.


The poly mailer market is anticipated to grow at a predicted pace of 4.70% from 2021 to 2028, reaching a valuation of roughly USD 1.69 billion as a result of their advantages and the expanding global e-commerce industry.


1.2 What are poly mailers made of?



Polyethylene, also known as polythene, is the most commonly produced plastic and serves as the primary raw material for manufacturing poly mailers. It is a crucial component in the plastics market, accounting for 34% of the total production with over 100 million tonnes annually.


Poly mailers are made using two main types of polyethylene: Low-Density Polyethylene (LDPE) and High-Density Polyethylene (HDPE).


LDPE poly mailers are known for their flexibility and stretchability, making them ideal for shipping items that require extra space, such as clothing, textiles, or soft goods. They have a lower density, giving them a softer touch, and a lower melting point. These mailers are non-toxic, tear-resistant, and offer high transparency.


On the other hand, HDPE poly mailers are sturdier and provide better puncture resistance, making them suitable for shipping items that need extra protection, like electronics or small gadgets. HDPE has a higher density, contributing to its harder texture and increased durability. These mailers can withstand higher pressures and have a higher melting point compared to LDPE, but they are less flexible.


1.3 What items can be shipped with poly mailers?



From clothing to electronics, poly mailers can handle a multitude of objects with ease. They are especially useful for lightweight and non-fragile items, but can also handle larger and bulkier goods. The items that can be shipped with poly mailers are mainly:




            Fabrics and yarns

            Phone cases




            Books and other printed materials


            Arts and prints


1.4 What are the benefits of poly mailers?



Easy packing and stress-free opening


The poly mailer features a peel-and-seal adhesive closure, maximizing packing efficiency and providing consumers with a stress-free opening experience.




These high-quality poly mailers are designed to be lightweight, reducing shipping costs.




Poly mailers are thin and foldable, making them a space-saving solution for businesses seeking to maximize storage areas.


Durable and penetration resistant


The poly mailers are made from durable materials, offering exceptional protection and resistance against wear, tear, and penetration during transit.


Customization for branding


Businesses can enhance their brand presence and create memorable customer experiences by customizing poly mailers with logos or branding, ensuring packages stand out and leave a lasting impression.


1.5 Does USPS accept poly mailers?


The answer is YES!


The United States Postal Service (USPS) and many other postal services worldwide accept poly mailers for shipping.


USPS First Class Mail


This service is suitable for packages weighing 13 oz or less, making it the most economical option for shipping lightweight items.


USPS Priority Mail


Packages weighing up to 70 lbs can be shipped using this service, and USPS is permitted to examine parcels to check their contents. Shipping charges are determined by distance and are typically predicted to take 1-3 business days for delivery.


USPS Media Mail


This cost-effective option is ideal for shipping books, CDs, and other printed materials.


Chapter 2: Eco-friendliness of poly mailers


2.1 Influence of plastic pollution



Plastic pollution has become a critical issue for humanity. We heavily rely on plastic across various industries, leading to an alarming production rate of 400 million tonnes of plastic waste annually. This trend is alarming as plastic production has outpaced all other materials since the 1970s, with a projected 1,100 million tonnes by 2050 if not curbed.


Single-use plastic items, especially packaging, contribute significantly to this crisis, with around 85 percent ending up in landfills or as unregulated waste. Moreover, the production of these plastics relies on fossil fuels, causing a substantial 19 percent of the global carbon budget by 2040.


It is clear that urgent action is needed to address plastic pollution and its harmful consequences on the environment and human health. Thus, plastic packaging recycling has become an extremely important subject.


2.2 Are poly mailers recyclable?



Yes! Poly mailers can be and should be recycled.


2.3 How to recycle poly mailers?


Recycling programs and guidelines can vary significantly from one area to another. It’s essential to be aware that not all recycling centers accept poly mailers. However, there are alternative options for recycling these materials.


Many grocery stores or big-box retailers like Home Depot, Whole Foods, and Targethave have initiated recycling projects that accept plastic bags like poly mailers. They have conveniently placed drop-off bins where customers can responsibly dispose of their plastic mailers.


2.4 Recycled poly mailers



Recycled poly mailers not only benefit the environment but also offer cost-effectiveness. They provide almost the same functionality and durability as mailers made from new materials, but they are cheaper in price.


As a business, you have the flexibility to choose between using 100% recycled materials or incorporating a certain percentage of recycled materials alongside new materials. This decision allows you to demonstrate your commitment to protecting the planet and embrace more sustainable practices in your operations.


2.5 Biodegradable and compostable options


Biodegradable poly mailers and compostable poly mailers have become increasingly popular among environmentally conscious consumers and businesses. These eco-friendly mailers are made from biodegradable polymers and bio-based components, designed to break down over time through microbial action, leaving behind natural elements.


While the prices of biodegradable poly mailers and compostable poly mailers can be up to several times the price of ordinary poly mailers.


2.6 Certifications from authorities


Eco-friendly poly mailers can obtain certifications from reputable authorities such as SGS and TUV. These certifications validate their adherence to stringent environmental standards and sustainable practices. By obtaining these certifications, businesses and consumers can have confidence in the authenticity of the mailers’ eco-friendly claims. SGS and TUV are globally recognized and trusted organizations that ensure the mailers’ materials, manufacturing processes, and overall environmental impact align with eco-friendly principles.


Chapter 3: How much are poly mailers?


3.1 Prices of custom poly mailers


If purchased in bulk from US suppliers with no special customization requirements, prices generally start at just 0.25$. However, for those looking to save even more money, overseas suppliers offer custom poly mailers in bulk with prices starting at just 0.05$.


3.2 Factors that influence prices



Material quality


The quality of the polymeric materials used in manufacturing the mailers can significantly impact the cost. Higher-quality materials may be more durable and offer better features, but they might also be more expensive.


Size and dimensions


Larger or custom-sized poly mailers will require more material and possibly more complex manufacturing processes, leading to higher costs compared to standard sizes.


Thickness and strength


Thicker and stronger poly mailers provide better protection for the contents, but they might be more expensive due to the increased use of materials.


Quantity and volume


Bulk orders typically enjoy economies of scale, leading to lower per-unit prices compared to smaller quantities.




Printed or branded poly mailers with logos, designs, or specific colors can add to the cost as they involve additional printing and setup expenses.


Chapter 4: How to customize your poly mailers?


Customizing your poly mailers to precisely match your unique marketing and shipping demands involves crucial decision-making on various aspects, such as types, materials, sizes, thicknesses, and designs.


4.1 Different types of poly mailers


Poly mailer bags come in various types based on their structure and features:


Regular self-sealing poly mailers



The standard option with no special features, suitable for general shipping needs.


Poly mailers with handles



These have die-cut handles on top for easy carrying and create a higher-grade impression on customers.


Clear-view poly mailers



Made with a transparent film on one side, allowing customers to view the contents of the package.


Wicket poly mailers



Ideal for companies with large shipment volumes, as they simplify the packaging process with tear-down function.


Returnable poly mailers



Feature double self-sealing strips, allowing the bag to be reused for future shipments, reducing plastic waste.


Poly mailers with tear strips



Have a perforated tear-off strip for easy opening.


Gusseted poly mailers



Designed with bottom and side gussets to increase loading capacity and provide extra protection for bulkier items.


4.2 What design files should be provided?


When customizing a poly mailer, you gain the opportunity to incorporate your branding, logo, and distinctive design elements, resulting in a unique and professional packaging solution. To ensure an effective design, consider the following aspects when preparing your design files.


File format


Preferred file formats for design artwork are typically high-resolution files, such as AI or PDF.




The resolution should be at least 300 DPI (dots per inch) to ensure a crisp and clear print.


Color mode



Use CMYK color mode for printing purposes, as it is optimized for four-color process printing. Avoid using RGB color mode, as the colors may not accurately translate to the printed version.




Convert all text to outlines or provide the fonts used in the design to avoid font substitution issues. This ensures that the text appears exactly as intended in the final print.


Graphic elements


Provide the links and ensure that all graphic elements (logos, images, icons) are high-quality and properly positioned within the design. Avoid using copyrighted images without proper authorization.


4.3 Tips for designing custom poly mailers


Package N’ Go is delighted to provide you with valuable tips to achieve the finest design for all your marketing and shipping requirements.


Patterns not extending to left and right edges



Avoid placing designs all the way to the left and right sides of the mailer bags due to potential cutting machine deviations. This can lead to patterns from one side ending up on the next mailer bag’s side, ruining the overall appearance.


Patterns not extending to bottom edges


It is suggested to avoid laying patterns at the bottom edges of the front and back sides of mailer bags. Small changes during folding could cause patterns to shift, resulting in unintended placements.


Limit colors in the design


Gravure printing used for mailer bags requires overprinting and strict machine requirements. To avoid issues with inaccurate or inferior overprinting, it is recommended to use no more than four colors in the design. Spot color or monochrome may be better for small text or lines.


Keep gluing area blank


Maintain functionality and cost-efficiency by leaving the adhesive area of the poly mailer free from any decorations. Keeping this area clean ensures a strong adhesion, prevents ink from compromising the adhesive quality, and avoids covering the decorations after the mailer is sealed.



Eye mark or locator mark


Finished mailer bags may have an eye mark or locator mark, a small black line strip that aids automatic cutting machines in precise trimming. Designers should be aware of this element, even if it wasn’t part of their original design.


Chapter 5: How are poly mailers made?


The production process of poly mailers primarily involves three main stages: film blowing, printing, and bag making.


5.1 Film blowing


Film blowing is a plastic processing method used to produce films by melting plastic particles and blowing them into a tubular film. High-pressure air inflates the film to the desired thickness. After cooling, the film is finalized. The film-blowing machine is crucial in this process, producing high-grade film packaging with excellent barrier properties, freshness preservation, and more.


Poly mailers, commonly used for shipping, are made of three layers of co-extruded film, offering advantages like transparency, puncture resistance, and heat sealing properties. The inner layer is often black or gray for confidentiality, while the outer layer is light gray. Customization options allow for specific design modifications.


5.2 Printing


Poly mailer bags are printed using a specialized gravure press, ensuring high-quality results. The process involves transferring the design onto a copper plate using gravure printing, ensuring precise ink application to designated areas. The inked plate is then pressed onto the co-extruded film to complete the printing process.


5.3 Bag cutting and bag making



After ensuring the printings meet the desired quality, the production moves to the final step of creating the poly mailer bags – bag cutting and bag making. In this stage, the co-extruded film is first laminated with the adhesive strip. The bag-making machine’s knife head then precisely cuts and heat-seals the film to create the poly mailer envelopes.


The hot melt adhesive used in this process plays a crucial role. It must possess specific characteristics like good initial adhesion, strong holding force, and resistance to oil seepage. Once bonded, the adhesive ensures the poly mailer cannot be easily torn, providing anti-counterfeiting and anti-theft functions. Therefore, selecting the right hot melt adhesive is essential for the bag-making process to ensure the production of high-quality poly mailer bags.


5.4 Turnaround


The turnaround time for custom poly mailers can vary based on several factors. In general, larger quantities and more intricate designs or techniques will necessitate a longer production period.


For instance, if a factory is producing 50,000 standard poly mailers without any customizations, they typically have readily available materials in stock, enabling them to complete the production in approximately 7 days. However, when it comes to the same quantity of custom sized poly mailers with 4-color printing, the factory needs to undertake plate making and material preparation, leading to a longer production time of around 15 days.


Chapter 6: How to do the quality inspection for poly mailers?


During and after the production process, quality control measures are meticulously incorporated into every session.


6.1 Why is quality inspection important?



Quality inspections for poly mailers are essential to maintain product integrity during transit, preventing any defects or weaknesses that could lead to damage to the items inside. They ensure customer satisfaction by providing a positive unboxing experience and avoiding negative reviews and potential loss of business. Additionally, inspections save costs by identifying and eliminating faulty mailers before shipping, while also upholding a brand’s reputation for professionalism and commitment to quality. Moreover, inspections enhance supply chain efficiency by addressing issues early, ensuring smooth manufacturing to delivery processes.


6.2 How many samples will be inspected?



To ensure strict adherence to quality requirements, we employ the AQL (Acceptable Quality Limit) inspection procedure. This involves randomly selecting a set number of samples from each batch and comparing them to established acceptance criteria. The number of samples inspected is determined by the order quantity and the required degree of inspection.


The AQL inspection consists of two parts: special inspection and general inspection. If the client does not have specific requirements, we typically use the standard criteria: CRITICAL DEFECT=0, MAJOR DEFECT=2.5, and MINOR DEFECT=4.0. A minor defect does not significantly impact product use, while a major defect might render it unsuitable for its intended purpose. A critical defect can be hazardous or even fatal if left unaddressed.


Special inspection, following the S-4 standard, primarily focuses on functional issues. We maintain a zero-tolerance policy for functional problems, and the discovery of even one bag with critical defects leads to the rejection of the entire batch. Functional issues may include severe stains like insects, blood, hair, or other dirt, as well as the presence of hazardous items such as blades. Additionally, poor sealing edge firmness and adhesive sealer firmness are considered severe problems that significantly affect user functionality.


For general inspection, we often use the level II criteria. Suppose the order quantity is 8000, corresponding to word code L with a sampling number of 200. In this case, MAJOR DEFECT=2.5 and MINOR DEFECT=4.0. The corresponding AC values for 2.5 and 4.0 are 10 and 14, respectively. Thus, among the 200 randomly selected bags, if there are no more than 10 bags with major defects and no more than 14 bags with minor defects, the batch is considered acceptable.


By employing the AQL inspection, we ensure that every batch of poly mailers meets stringent quality standards, providing our clients with high-quality products that meet their expectations and specifications.


6.3 Quality inspection criteria


Poly mailer dimensions


Accurate measurements are crucial for poly mailers. The length and width must be carefully examined during the inspection, with a strict 3mm tolerance to avoid any issues. Providing precise dimensions ensures a successful outcome and prevents costly setbacks.





To maintain the highest standard, the product’s thickness is tested using a professional micrometer. It must fall within the specified range, like a +/- 0.4cmm margin for 6cmm thick poly mailers. Deviations outside this range result in the package being deemed unfit for purchase.


Film color


Quality assurance for poly mailers goes beyond the human eye. Advanced equipment is used to ensure the colors meet stringent expectations, guaranteeing only quality products for consumers.


Ink saturation


Achieving a professional look requires optimal ink saturation. Even and consistent ink coverage is essential, striking a balance between being too dull or too bright. This level of perfection ensures neatness and meets professional standards.


Ink adhesion


Two methods are employed to evaluate ink adhesion. The printing surface is covered with special tape and slightly stretched to measure adhesion strength accurately. Rubbing the surfaces together also provides information about effective ink adherence.


Film stretching force



Poly mailer film’s stretching ability is vital to ensure it can securely hold its contents. In-house evaluation verifies the polymer film’s tensile strength both vertically and horizontally, ensuring it performs as intended.


Edge sealing firmness


Edge sealing significantly impacts strength, durability, and safety compliance. A violence test evaluates the seal’s effectiveness under different force levels. This ensures superior poly mailers that meet industry standards and perform well.


Adhesive sealer firmness



The poly mailer sealer must be firm to keep items secure during transit, preventing wear and tear or damage. This layer of defense ensures the items arrive at their destination in optimal condition.


Carton details


Thoroughly inspecting cartons containing poly mailers is crucial. The QC team checks for the correct number of bags, undamaged cartons with clear markings, and proper sealing. Weight is also verified to ensure it meets the required limits.


Stack details


During inspection, stack details are closely checked. The legs of the stack must be complete and aligned, with proper wrap-around films and tapes to protect the cartons. Ensuring complete protective corners guarantees the products’ safe arrival in perfect condition.


6.4 Who does the quality inspection for you?


Quality inspection from the supplier


At Package N’ Go, we have a dedicated team of highly qualified experts and state-of-the-art facilities for quality inspection. Our team is trained to identify even the smallest flaws to ensure that every delivery meets high standards. We provide complete transparency and issue comprehensive inspection reports to give our clients peace of mind.


Quality inspection from a third party


For those seeking extra assurance, we offer the option of third-party inspections. We work closely with reputable inspection institutions to ensure the validity and thoroughness of their analyses, resolving any difficulties promptly. You can rely on our support throughout the process if you opt for a third-party examination.


Some of the reputable inspection institutions we collaborate with include:

SGS: A highly regarded global organization with over 90 branches and 200 laboratories worldwide. Their 15,000+ skilled specialists provide quality assurance and a trusted seal of approval.


TUV Rheinland: A global leader in product inspection and certification, with over 130 years of experience. The German Technical Inspection Agency Network (TUV) maintains high-quality standards across 30+ countries. Their rigorous test methods ensure only top-notch safety and quality products enter the market.


Chapter 7: Conclusion



We have covered every aspect of custom poly mailers in depth in this extensive guide. With a cutting-edge supply chain focused in China, Package N’ Go is a reputable American company with a global presence. We have developed into a renowned leader with more than two decades of experience thanks to our unrelenting dedication to providing custom packaging solutions.


We take pride in providing a wide selection of custom packaging goods, such as custom bubble mailers, custom boxes, and custom poly mailers. Whether you are a startup or a large company, Package N’ Go is completely prepared to meet your specific needs. With 10,000 mailer bags and 500 boxes, our extremely low minimum order quantities (MOQ) are the industry standard. Contact us right away to take advantage of Package N’ Go’s outstanding packaging options.

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