Complaints about pet food packaging are rarely focused on material quality, but instead center on several very specific issues: tearing near the handle, leakage from the bottom seam, deformation starting from the eighth layer in stacked packaging, the food developing an off smell after two weeks of opening, or users complaining about the narrow bag opening making it difficult to scoop. These issues can be predicted during the bag selection phase, provided that net content, stack height, and usage method are first determined, and then the bag type can be discussed accordingly.
Many teams take the opposite approach: they first look at the bag types used by competitors, then have the factory replicate them. The risk with this approach is that the load-bearing paths for the same stand-up bag can be completely different when packaging 2 kg versus 12 kg— the former focuses on shelf performance, while the latter depends on structural strength.
Start with net content and stacking capacity, rather than selecting bag type first.
The specifications for main food packaging are clearly defined. Sample packs and trial packs are usually under 1 kg; daily retail packaging ranges from 1 to 5 kg; multi-pet households and bulk packs start from 10 kg and above. Once the weight range is determined, the main load is also determined.
Light-duty bags are not suitable for static loads, so the focus should be on the design, opening, and resealing. Heavy-duty bags become part of the handling system, and the handles, bottom seal, and side seals must all bear weight. It is recommended to write down three numbers before sample making: the maximum net content per bag, the planned number of stacked layers, and the longest storage time from the factory to the end user. These three numbers will directly determine all subsequent decisions.
Different bag types solve different problems.
Side Gondola Bag: Mainstay for Medium to Heavy Specifications
The side gusset of the side gusset bag folds out to form a rectangular shape, ensuring a stable cross-section when stacked and high space utilization when loaded into a container. However, the fold line creates a stress line, and the sealing at the root of the folded edge must be evaluated separately and cannot be treated the same as standard edge sealing. Refer to the bag type and structure description for details.Pet Food Packaging Solutions。
Flat Bottom Bag and Octagonal Sealing: Priority on Standability and Print Layout
Flat-bottom structure allows the bag to stand independently, ensuring complete printing area and a premium appearance on shelves. The downside is an additional layer of material and one more forming process, making the bottom corners the most vulnerable during drop tests. Eight-sided sealing creates folded edges on the sides, making the bag more square and improving stacking neatness, but it involves more bag-making processes, leading to higher costs for small batches.
Stand-up bag: standard size for medium and small specifications
Stand-up bags dominate the market in the range of 1 to 5 kilograms. The main limitation is the bottom seal, which must withstand the weight of the contents while remaining functional after multiple openings and closings. When increasing the specifications, widening the bottom and thickening the film are common compromises, but these changes affect both cost and the feel of the opening.
Roll Film: Cost Analysis When Specifications Are Stable
Low cost per roll of film is only possible if the production line can make its own bags. It requires the material width, heat-sealing layer, and packaging machine dwell time to be well matched. It also has poor flexibility for changing specifications or changing print designs. When orders are scattered or design updates are frequent, using roll film is often not cost-effective.
Standing on the production line: can the bags and equipment match up?
The performance of the same bag can vary significantly across different filling machines. Drop height, sealing time, cooling method, and clamping method all affect the edge sealing quality.
Main feed is mostly in pellet form, resulting in significant impact during discharge, requiring stable positioning at the bag opening; formulas containing freeze-dried chunks or coating powder will generate dust and debris, easily contaminating the sealing area. A feasible approach is to isolate the discharge outlet from the sealing area and establish fixed cleaning schedules on the production line, rather than only tightening inspection criteria at the final inspection stage. The temperature, pressure, and time of heat sealing are interdependent; adjusting any one parameter alone may push the sealing edge into a critical state. Relevant process instructions can be referred to as follows:Packaging Process Description。
Stacking and Transportation: What Bags Endure in the Warehouse
High-density main feed results in bags weighing over 10 kg per board. Once stacked to a certain number of layers, the bottom layer must bear the weight of the entire stack for a long time. Compressive load, warehouse humidity, and time all act together: stacking for a week may be fine, but it doesn’t necessarily mean the entire storage period will be problem-free.
Transportation distance will further affect the conditions. Domestic full-truckload transportation mainly involves short-term vibration and multiple forklift handling; export container transportation adds long-term vibration, wider temperature differences, and high humidity during sea transport. The bag’s tensile properties can be tested according to ASTM D882 The method discussion, the seal strength can be referred to ASTM F88But more importantly, it allows you to not only obtain the data but also clearly identify where the bag actually failed.
More effective actions are usually changing the stacking method and applying external packaging constraints: adjusting the number of layers, using a more stable arrangement, adding more shrink wrap or separators, and letting the outer box share part of the load. Adding thicker film only rarely solves the creep issues caused by stacking height.
The first few weeks after opening are the real test.
Large main feed bags, once opened, are used for several weeks. After opening, the barrier performance is no longer the determining factor. What remains is whether the bag can be effectively resealed and how much air is exchanged each time the contents are accessed.
Zipper solutions address repeated sealing, but the relative position between the zipper and the top edge, the opening and closing force, and whether dust particles will get stuck in the teeth need to be considered. A wider opening makes it easier to scoop and allows more air exchange, while a narrower opening better preserves flavor. However, when using a large spoon with large grain particles, the experience may worsen. These trade-offs should be discussed based on real feeding habits, rather than judged solely on design drafts.
The handle belongs to the same category of issues. Die-cut handles are cost-effective and suitable for medium-sized specifications; however, for larger sizes, independent handles or handles with added width provide better force distribution. If the handle is too tight, users will switch to dragging the bag, which actually shortens the bag’s service life.
Sample Confirmation Checklist
Do not pass by appearance inspection in one go; please record the following items:
- The actual upper and lower limits of net content achieved on the production line, rather than the nominal value.
- The sealing condition of the folded edge root, bottom corners, both ends of the handle, and the bag mouth should be checked separately, not just the middle section of the seal.
- Measure dimensions after 24 hours of filling, as the film material relaxation will affect the actual footprint.
- Stack one board according to the planned number of layers, press and leave it for a period of time, then inspect from the bottom up.
- Use real pet food for the opening and closing cycle; do not use substitutes.
Customization process and sample making can be referred to as follows:Custom PackagingCommon specifications can be referenced in the product center.
Several commonly overlooked judgment points
Should the handle be added or not?
If the end use involves manual carrying, a handle is required, but it should be designed based on the actual weight rather than adding a die-cut hole on the retail bag. If the application involves mechanical handling on a full sheet, designing the bottom and side edges for mechanical handling is more practical than adding an extra handle.
Is thicker always better?
Stacking performance is more dependent on the bottom geometry, the creep characteristics of the film material, and the stacking method, rather than just thickness. Increasing thickness will raise costs and may also narrow the sealing window, making it suitable only as a final step after other structural solutions have been tried.
Can trial packs and bulk packs share the same structure?
It is generally not recommended. For smaller sizes, the focus is on shelf appearance, opening feel, and print details, while larger sizes emphasize load-bearing path and sealing reliability. A structure covering a wide weight range will compromise at both ends. A more reliable approach is to split the weight range and design separate structures for each segment.
Common Questions
What material combination is reliable for pet food packaging bags?
There is no single answer. The choice depends on net content, whether nitrogen flushing is required, whether light protection is needed, and whether recyclability is a consideration. Common candidate structures include those with nylon layers for puncture resistance, and those with metallized or EVOH layers for barrier properties. Once the direction is determined, samples must be made based on the product content and distribution conditions; conclusions cannot be drawn solely based on material names.
How many layers are typically stacked?
There is no universal value. It is related to the dimensions after filling, the material of the film, the folding edge structure, warehouse temperature and humidity, and stacking time. A feasible approach is to conduct full sheet tests based on the planned number of layers. After leaving them under set conditions for a period of time, check the bottom layer and decide whether adjustments to the arrangement or additional outer packaging constraints are needed.
Why do problems still occur even after the edge sealing parameters are properly adjusted?
Normal variations in the heat-seal layer formulation and thickness tolerance of roll film batches, along with changes in workshop temperature and humidity and equipment wear, are common. The same set of parameters may not fall within the process window for different batches. It is recommended to fix a set of verification methods, and retest after changing batches or after long periods of downtime, rather than confirming only once during initial setup.
What additional precautions should be taken for export orders?
The vibration, temperature variation, and humidity during sea transportation are wider than in domestic transport, and the transportation duration is longer. The stacking plan needs to be reassessed. Additionally, different markets have their own requirements for labeling and ingredient declarations of pet food. The packaging layout should reserve corresponding positions. Refer to the following for guidance. FEDIAF Pet Food DeclarationUnderstand the basic framework of the European market; specific terms still need to be confirmed on a country-by-country basis.