Food Packaging: “Direct Contact” vs. “Indirect Contact”—3 Real Differences: Who Is Liable, Who Issues the Report, and Which Work Is Outsourced

At the end of last year, a client in the baking industry brought his product to our factory and pointed to the printed surface of the outer box, asking: “This box does not even hold the bread, so why did the customer complain that our bread smelled like ink?”

His outer box contained a paper tray, and the tray held the bread. The paper tray was in direct contact, whereas the outer box was not. But the customer’s concern was not baseless—the bread really did smell like ink.

Investigation revealed a different story: the paper tray supplier had provided a material declaration for “food-grade paper,” but a layer of PET barrier film had been laminated onto the outside of the paper tray for oil resistance. The lamination used an alcohol-soluble adhesive, and the solvent in this adhesive slowly seeped inward. The ink odor did not come from the outer box’s ink transferring onto the bread; it came from substances in the laminate being trapped between the paper tray and the bread.

This is the dividing line we will discuss today.

First Difference: The Dividing Line Is Whether Migratable Substances Have a Pathway, Not Whether There Is Physical Contact

The logic of the GB 4806 series begins with food-contact materials. Whenever there is a possibility of migration between a material and food, the migratable substances must be controlled. Direct contact is an obvious category: the paper tray touches the bread directly, leaving only one step in the migration pathway.

Indirect contact is another category: packaging materials that do not directly touch food but may affect the food.

The key is how “indirect” is applied in practice. The determining factor is not whether the packaging physically touches the product, but whether migratable substances have a pathway to reach the product. There are three common forms of indirect contact:

The third situation is the easiest for printers to misjudge. In a composite structure, “which layer touches the food” and “which layer the ink is printed on” are two separate questions.

A typical mistake involves an aluminum foil composite bag in which the foil layer is on the inside and touches the food, the printed layer is outside the foil, and an adhesive layer sits between them. The ink is separated from the food by the foil and adhesive, creating a long pathway. However, the adhesive layer is only one layer of foil away from the food, and if the adhesive is solvent-based, the migration pathway for residual solvents is actually shorter than that of the ink.

Our factory uses a rule for composite structures that is rather crude but highly effective: Peel open the composite bag and inspect it layer by layer. If the layer next to the food is separated from the ink layer only by adhesive, manage that layer according to the standards applicable to direct contact. Therefore, we never make the convenient judgment that the printed layer of a composite bag is safe because “there is aluminum foil in the way anyway.”

Second Difference: The Responsible Parties Differ, and the Reports Are Not the Same

This is the first issue a printer should clarify: Direct-contact and indirect-contact compliance responsibilities fall on different parties, while brand owners often approach only the printer.

To break this down:

There is a particularly common scenario in which responsibility is shifted: When a brand owner places an order with a printer, it verbally says, “It is just an outer box, so print whatever you like,” without specifying the ink grade. The printer uses conventional ink, but when the finished product causes a problem, the brand owner says, “You printed the box.”

Our practice is to include one fixed sentence on the quotation and process sheets for such orders: “This order’s outer box uses conventional ink, which is not food-contact grade, as confirmed in writing by the customer.” Writing this sentence costs nothing, but its effect is not zero. If the customer signs it, responsibility lies with the customer. If the customer does not sign it, we switch to food-grade ink and reflect the cost difference in the quotation.

Conversely, there is also a cost when a printer proactively uses food-grade ink without a customer request. Food-grade ink has a higher unit price, a slightly narrower color gamut, and some Pantone colors may be impossible to match. If the customer did not request it and the printer quietly uses it, the printer absorbs the cost. The ink grade must therefore be confirmed rather than guessed.

Third Difference: The Outsourcing Arrangements Are Entirely Different—Why Printers Cannot Take On Direct Contact

The third difference is the hardest dividing line in practice and the most useful lever for printers when negotiating the division of responsibilities with clients.

The testing responsibility for direct-contact materials belongs to material suppliers and laminators. The printer’s role in this part is to “perform the printing properly,” not to “guarantee food contact.”

The reason is straightforward: migration testing must be conducted with specific food simulants, at specific temperatures, and for specific durations, and it requires a report from a third-party laboratory. These reports apply to a specific material formulation. Does the printer’s printing process change the material?

Yes. Three typical situations are as follows:

• Primer and adhesive—A primer is added to improve adhesion. If it is placed between the ink and the substrate, its residues fall within the scope of the migration assessment.
• Coating and lamination—Water-based coating has its own formulation compliance requirements, as does the adhesive used for lamination. Once the printer adds this layer, the original material supplier’s compliance conclusion does not automatically cover it.
• Die cutting and forming—Fiber exposure at cut edges and stress caused by pressure must be evaluated when the material is used for food contact.

The professional division of responsibilities is therefore as follows:

This is why printers cannot take on an entire food-contact package: The problem is not that printers are unwilling to assume the responsibility. The technical chain of responsibility spans two different suppliers, and printers lack the ability to verify whether the other supplier’s report remains valid after their own processes have been completed.

On the other hand, the printer’s role in indirect contact is clearly defined: For color cartons, shipping cartons, and labels, the printer is the sole responsible party. When a client asks, “Who is responsible for this box?”, the answer can only be the printer. The value of this work lies in accountability, not in a low price.

Three Questions That Establish the Division of Responsibilities

For orders of this kind, especially the first order from a new client, our factory always asks three questions:

1. “Which layer of this package directly touches the product?”—The answer is usually the inner tray, inner bag, or bottle body. Clients often cannot answer because the product packaging is assembled from components supplied by several companies.
2. “Who supplied this layer, and can we obtain its compliance documents?”—If the material is not in our possession and no report is available, the package currently has no established basis for compliance.
3. “What ink grade is required for indirect-contact packaging such as an outer box?”—If this is not asked, we default to conventional ink and leave a written record of that decision.

Once these three questions have been answered, the client’s packaging compliance responsibilities change from a vague arrangement into a checklist identifying who signs which document.

Returning to the baking client from the beginning, his problem was not actually with the outer box: The outer box’s ink was compliant. The problem was that the paper tray supplier’s “food-grade paper” declaration did not cover the additional PET lamination applied to the tray. Whoever added the lamination beyond the paper tray supplier should have had the report redone. Packaging responsibility is never assigned according to which box it is, but according to which layer touches the product and which layer was newly added.

Further Reading

The following articles belong to the same series:

• How to Read the 9 Standards in the GB 31604 Series for Food-Contact Packaging—What migration testing specifically measures
• A Practical Guide to GB 4806 Testing for Food-Contact Packaging—5 commonly challenging test items and corrective actions for failed tests
• 6 Types of Mandatory Labeling for Food Packaging—Which layer the labeling belongs to and who bears responsibility
• 4 Real Cases of Migration Limit Exceedances in Food Packaging Printing—Four sources: ink, adhesive, lamination, and coating
• 4 Types of High-Risk Labeling Claims Under the Packaging Advertising Law—Another type of joint liability for which the printer drafts the wording