Three Practical Limits to the "Recycling Cycles" of Recycled Packaging Fibers: EN 643 Classification / Deinking Residues / Fiber-Strength Degradation — The First Three Numbers a Printer Should Ask for an Inquiry Such as "How Many Layers Can This Recycled Paper Print?"
💡 💡 At a Glance
There are three practical limits to the recycling cycles of packaging fibers. First, EN 643 (Paper and Board for Recycling) grades recovered paper by the permissible proportion of non-fiber components rather than simply labeling it recycled paper. Most grades permit 1.5% non-paper components, while total unwanted materials are generally limited to 2.5%. Laminations, composite layers, metal parts, and adhesive strips all consume this allowance. EN 643 also recommends keeping shredded paper pieces as large as possible, so packaging that consumers can retain without shredding has greater value. Structural design should therefore include a non-fiber-component grammage budget. Second, deinking residues determine compliance in direct food-contact applications. Incomplete deinking reduces the brightness, whiteness, and strength of recycled pulp and may leave residual alkali, oil, and migratable substances. Verification should cover the source of the material, post-deinking pulp specifications, and migration testing of the finished package under GB 31604.1. The finished-product test is the printer's responsibility. Third, fiber-strength degradation is the physical basis for the maximum number of recycling cycles. Repulping, screening, contaminant removal, deinking, refining, and papermaking each shorten fibers and reduce strength. Higher recycled-content ratios therefore reduce stiffness, folding endurance, and die-cutting crack resistance. Remedies range from localized virgin-fiber reinforcement and structural redesign to increasing the grammage of the entire box. The three numbers printers should request first are the calculation basis for the recycled-content ratio, the grammage share of non-fiber components, and the corresponding fiber-cycle count and mechanical-performance data.
In September 2026, an e-commerce client brought us a paper sample.
"We want a higher recycled-content ratio for this paper, for environmental reasons."
We asked: "How high?"
The client said: "100%. Fully recycled."
We held the sample up to the light for a while and asked: "What will this box contain?"
The client said: "Laundry detergent pods, the kind that come individually wrapped."
We replied: "Then it cannot be 100% recycled."
The client said: "Why? Isn't paper supposed to be infinitely recyclable?"
We explained: "Paper can certainly be recycled, but with every cycle, the fibers become shorter and weaker. Your product is in direct contact with the contents, and its surface is alkaline. The residue that cannot be removed is precisely where migration comes from."
The client's statement—"paper can be recycled forever"—is one of the most common misconceptions in the industry. It treats "recyclable" as a promise about a material, whereas in reality it is a promise about a system: whether paper can continue to be recycled depends on whether, after collection, there is a buyer willing to purchase it at the prevailing per-ton recycling price. That buyer will exist only if the paper is sufficiently clean and sufficiently uniform to be processed normally by a downstream recycled-pulp mill.
Therefore, this article will not focus on "environmental benefits." Instead, we will examine three verifiable figures: how EN 643 classifies recovered paper, where deinking residues create a compliance limit, and how fiber strength declines.
The First Limit: EN 643 Classification Is More Than the Words "Recycled Paper" — It Grades by the Permitted Level of Non-Fiber Components
Europe's grading system for recovered paper is EN 643, Paper and Board for Recycling, the European list of standard grades of paper and board for recycling. The core of this system is not color, nor recycled-content percentage, but the permitted proportion of non-fiber components in each batch of recovered material.
What counts as a non-fiber component? Coatings, laminate layers, spiral binding, and anything else that is not paper fiber, as well as other contaminants. EN 643 establishes a maximum permissible proportion of non-paper components for each grade, with most grades set at 1.5%. It also establishes a separate limit for total "unwanted materials," generally 2.5%.
What does this mean for a printer? Every additional packaging operation consumes part of that 1.5% allowance.
The client asked: "This box will be laminated. Does the film count as a non-fiber component?"
We replied: "That depends on the type of film and the application method. EN 643 addresses one-sided or two-sided polymer coatings separately: if the coating falls within the grade's specific description, it is not treated as a non-paper component; if it is not covered by the grade's specific provisions, it is treated as unwanted material. Composite paper, metal fasteners, and adhesive strips must all be included."
This allowance therefore has to be budgeted during structural design. If a client wants a paper box that is simultaneously recyclable, equipped with a metal hang tag, and fitted with a moisture barrier, the latter two requirements spend part of that 1.5% allowance.
There is also a highly practical recommendation for printers: the EN 643 guidance recommends keeping shredded paper pieces as large as possible. This means that packaging delivered to the recycling stream has value when consumers can keep it intact rather than tear it apart. Shredding it into small pieces reduces its usability for the paper mill. This may sound obvious, but structural design decisions such as "Should the handle be torn off?" and "Should the wrap-around label be removed and discarded?" directly affect grading at the recycling stage.
The client said: "So we need a design that can be dismantled intact without shredding?"
We replied: "At minimum, consumers should not have to shred it to recycle it. That is where design can make a contribution."
The Second Limit: Deinking Residues — Whether Food Contact Is Possible Depends on Whether the Paper Has Been Deinked Thoroughly
Deinking removes the ink layer from recovered paper so that the fibers can once again be repulped. Incomplete deinking has two consequences.
The first is pulp quality: residual ink spots, pigment, and adhesive reduce the brightness, whiteness, and strength of recycled pulp across the board. The paper mill must then lower the proportion of recycled pulp in its furnish, meaning that recycling has effectively made a full turn in the supply chain without delivering its intended benefit.
The second is direct-contact compliance. This is the area for which printers truly bear responsibility. Recycled-fiber packaging intended for food contact is subject to corresponding testing requirements for degree of deinking, residual alkali, residual oil, and migration limits. In earlier articles, we discussed GB 4806.13 for composite materials, GB 4806.14 for inks, and deinking residues and migration limits for recycled-fiber food-contact packaging. That article focused on the wording of the standards; this article focuses on how a printer determines whether a supplier's recycled pulp is usable.
The client asked: "The supplier says the recycled pulp is food grade. How do we verify it?"
We replied: "Ask for three things.
First, the source of the food-grade recycled material. Waste cardboard and mixed household recyclables have uncontrolled sources, and such pulp is unsuitable for packaging in direct contact with food. Industrial recovered material—production trim and clean waste-paper trimmings—has a controlled source and may therefore be eligible for this application.
Second, the deinking process and post-deinking pulp specifications. Ask for post-deinking pulp data, including residual alkali, residual substances, and the whiteness and ash content of the finished sheet. Ash content is a particularly intuitive indicator: a high ash content means that more impurities have carried through.
Third, migration testing of the finished package. After printing, the finished package must undergo migration testing under the GB 31604.1 method. This is the printer's own responsibility; the supplier cannot perform it on the printer's behalf. A supplier's pulp passing its own tests does not mean that it will remain compliant after printing on your substrate with your inks and varnishes.
The client asked: "So do we have to retest every time the pulp changes?"
We replied: "Retest when the pulp changes, when the substrate changes, and when the same pulp is used at a different thickness. The most cost-effective approach is to select one pulp supplier, lock down the substrate-and-process combination, and conduct one complete combined validation. Retest only when materials change. This combined validation costs far less than trying to remedy a failure after it occurs."
Regarding specific deinking methods, suppliers most often mention "flotation deinking" and "wash deinking." Their principles differ, but the results must ultimately be expressed through the same set of figures. A printer is not interested in the principle; it is interested in the final product data. This is consistent with how we assess any supplier's standards: do not focus on what process a supplier claims to use; focus on the data it can provide, the testing methods it uses, and the reports it can issue.
The Third Limit: Fiber Strength Declines in Every Cycle — The Physical Basis for the "Maximum Number of Recycling Cycles"
This is the limit most likely to be overlooked, yet it determines the cost structure.
During recycling, paper fibers undergo repulping, screening, contaminant removal, deinking, refining, and papermaking. Each step reduces fiber length and strength. Wood fibers are naturally short and brittle. Their ends are torn apart during repulping and shortened further during refining, resulting in a marked decline in fiber strength after multiple cycles.
This creates a very specific commercial consequence: each increase in recycled-content percentage reduces the paper's stiffness, folding endurance, and die-cutting crack resistance. In practical terms, for the same box design, the version with a higher recycled-content ratio is more likely to crack along creases, develop crushed edges during die-cutting, and wrinkle during gluing.
The client said: "We tried it, and the boxes were indeed prone to deformation."
We replied: "This is a fiber-strength issue, not a printing issue. There are three ways to address it: increase the grammage and number of layers, use virgin fiber in critical load-bearing areas, and modify the structure so that forces are directed away from the weakest paper layer. The third approach is often overlooked. For example, handle roots, box corners, and the junctions between bottom panels and side panels can be selectively reinforced with virgin paper at a cost far below increasing the grammage of the entire box.
So how many times can it actually be recycled? There is no single answer. It depends on several variables, including the source and length of the original fibers, the intensity of processing in each cycle—more severe deinking and refining cause greater strength losses—and the target strength of the finished paper. In industry, the more common approach is not to count the number of cycles but to determine whether the mechanical performance of the final product meets the required standard. This assessment should be performed by the paper mill because the mill understands the actual effect of each processing cycle on the fibers.
Therefore, when a client asks, "How many times can this batch of paper be recycled?" the honest answer from a printer is: this depends on how the recycling stream processes it, and the printer cannot make that promise. A printer can commit to two things. First, it can control the proportion of non-fiber components in this batch so that it remains within the range accepted by the recovered-paper grading system. Second, if the application involves direct food contact, the printer is responsible for the migration safety of the finished product.
When a Printer Receives an Inquiry Such as "How Many Layers Can This Recycled Paper Print?" — The First Three Numbers to Ask for
Three figures, none of which concerns the process. All concern measurable parameters.
First: What is the maximum allowable recycled-content ratio, and how is that ratio calculated? Is it based on the total weight of the finished product, the weight of the fiber portion, or the supplied batch? Depending on the calculation basis, the same "60%" can produce a substantial difference in cost.
Second: What is the grammage share of non-fiber components in the finished product? Lamination, composite layers, metal parts, and adhesive strips must all be included. Compare the total with EN 643's 1.5% permissible limit to determine how much headroom remains. This figure must be established during structural design, not calculated after printing.
Third: How many fiber recycling cycles does this ratio correspond to, and what are the strength specifications? Request mechanical-performance data from the paper mill, such as stiffness, folding endurance, or ring crush strength, rather than accepting grammage and whiteness alone. All three figures are needed to determine whether the paper will perform successfully in the intended box design.
One Sentence for Clients
Regarding recycled paper, the most important message we want to convey to clients is: "Do not ask how many times it can be recycled. First, ask how many grams of non-fiber components it contains."
The client said: "But all the environmental advertisements say it is recyclable."
We replied: "Recyclability is a matter for the recycling system, and you cannot control it. The grammage of non-fiber components is something you can control through design. A paper box that will not fall apart when shredded, does not need to be torn apart, and has no composite layer has far greater value to the recycling system than a percentage printed on an environmental brochure."
Further Reading
- Three Practical Limits to Recycled-Fiber Food-Contact Packaging — the regulatory framework for deinking residues and migration limits
- Recycled Paper vs. Virgin Paper for Packaging: A Real Cost Comparison Across Three Brand-Positioning Scenarios — calculating the costs at different recycled-content ratios
- The Impact of 30% / 50% / 100% Recycled Content on Printability — how changes in recycled content affect color and ink uptake
- How Three Types of Accessories Defeat the "Recyclability" of Paper Packaging — how magnets, metal fasteners, and PVC windows turn paper into mixed material
FAQ
Why is "paper can be recycled forever" a misconception?
Because whether paper can continue to be recycled depends on the recycling system and on whether a buyer is willing to purchase it at the prevailing per-ton recycling price after collection. That buyer will exist only if the paper is sufficiently clean and uniform for a downstream recycled-pulp mill to process normally. If a package contains too many components—such as films, metal parts, adhesive strips, or inseparable composite layers—it becomes unwanted material at the recycling stage, and the paper mill may either downgrade it or reject the entire batch. What is genuinely controllable is the amount of non-fiber material in the product, rather than the theoretical number of cycles the paper can undergo.
How is the EN 643 limit of 1.5% calculated, and how should a printer allocate it?
EN 643 establishes a maximum permissible proportion of non-paper components for each recovered-paper grade, with most grades set at 1.5%. It also establishes a separate limit for total unwanted materials, generally 2.5%. For printers, every additional operation spends part of that 1.5% allowance—including lamination, composite layers, metal hang tags, and bonded components. The treatment of lamination depends on whether the film type and application method are covered by the grade's specific description, while composite paper and bonded dissimilar materials must be included. Create a "non-fiber-component grammage budget" during structural design, add up the grammage of each component, and compare it with the limit. Do not wait until after printing, when the structure can no longer be changed.
A supplier says its recycled pulp is food grade. How should a printer verify this?
Ask for three things. First, the source of the food-grade recycled material: mixed household recyclables have uncontrolled sources, while industrial recovered material, such as production trim and clean waste-paper trimmings, has a controlled source and may be eligible for direct food-contact applications. Second, the deinking process and post-deinking pulp specifications, including residual alkali, residual substances, and the whiteness and ash content of the finished sheet; high ash content usually indicates that more impurities have carried through. Third, migration testing of the finished package under GB 31604.1. This is the printer's responsibility and cannot be delegated to the supplier: compliant pulp does not necessarily remain compliant after printing on your substrate with your inks and varnishes. The most cost-effective approach is to select one pulp supplier, lock down the substrate-and-process combination, conduct one complete combined validation, and repeat the validation only when materials change.
Why can two papers both labeled as 60% recycled differ significantly in strength?
The differences usually arise from three factors. First, the calculation basis for the recycled-content percentage may differ: whether it is based on the total finished weight or the fiber weight can produce a large difference in actual recycled content for the same stated "60%." Second, the quality of the recovered material varies; the cleanliness of deinking and the level of impurities directly affect the whiteness and strength of the finished sheet. Third, the fibers may have undergone different numbers of cycles and levels of processing intensity, with more severe treatment producing greater strength losses. When comparing suppliers, do not compare the "60% recycled" label alone. Ask both suppliers for mechanical-performance data, such as stiffness, folding endurance, and ring crush strength, because these figures determine whether the paper is suitable for your box design.
Beyond increasing grammage, what can be done when increasing recycled content makes boxes prone to deformation?
There are three approaches, ordered by cost-effectiveness. First, selectively reinforce critical areas with virgin fiber. Handle roots, box corners, and the junctions between bottom and side panels are stress concentrations, and replacing these areas with localized virgin paper layers costs far less than increasing the grammage of the entire box. Second, modify the structure so that forces avoid the weakest paper layer, for example by changing the direction of loading or transferring opening and closing forces to other components. Third, increase the grammage or number of layers throughout the box. This final option increases both cost and material waste, so it should be considered only after the first two approaches have been fully explored. In addition, a structure that allows the entire box to enter the recycling stream without shredding offers more practical value at the recycling stage than an additional 10 percentage points of recycled content.
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