Food Packaging Printing "Migration Exceedance" 4 Real Cases — Where Ink / Glue / Lamination / Varnish 4 Sources Fail

In June 2024, a customer in Zhejiang doing food packaging (making paper cups for a milk tea brand) called in a panic: "Our paper cups were spot-checked by the market regulator, migration exceeded the limit, the entire batch of 100,000 cups was recalled, losses over 300,000 RMB. Can you help us find out exactly where the problem is?"

I asked him to send over the test report. The exceedance item was "overall migration" (4 simulants: distilled water, 4% acetic acid, 50% ethanol, olive oil), exceeded by 1.5x. The customer's exact words: "We use water-based ink + water-based glue + matte lamination, why does it still fail?"

I asked the customer to send the factory test reports for their ink, glue, lamination, and varnish. After comparing, the problem was in 1 of the 4 processes: the lamination. The customer used EVA adhesive layer (ethylene-vinyl acetate copolymer) for lamination. EVA adhesive layer releases vinyl acetate monomer in the 50% ethanol simulant, causing overall migration to exceed the limit.

The customer said: "We've been using EVA adhesive layer all along, never had a problem before."

I said: "It's not that the EVA adhesive layer itself is problematic, but that this particular order's food contains alcohol (milk tea ingredients contain edible alcohol), only the 50% ethanol simulant would catch the exceedance. Previous orders, if they were all water-based foods, wouldn't trigger this exceedance item."

This is the most common real scenario for food packaging migration exceedance: both customers and press shops are unfamiliar with the specific test items of GB 31604 series standards, causing press shops to use materials and processes that are compliant but mismatched with the food type.

4 Sources of Food Packaging Migration Exceedance

Source 1: Ink Migration Exceedance

3 common reasons for food packaging ink migration exceedance:

1) Metallic inks (gold ink / silver ink / pearlescent ink): contain small amounts of heavy metals (lead, cadmium, barium), may release in 4% acetic acid simulant. The most common pitfall: customer wants gold/silver effect, press shop uses ordinary metallic ink on outer layer of food packaging, metal ions migrate to food.

2) Dye inks (red ink / yellow ink): contain azo dyes, which may release aromatic amines in 50% ethanol simulant. The most common pitfall: customer wants bright red/yellow food packaging, press shop uses ordinary dye ink, azo dyes exceed limits.

3) UV-curable inks: contain photoinitiators (such as benzophenone), which may migrate in olive oil simulant. The most common pitfall: customer wants UV spot varnish effect, press shop uses ordinary UV-curable ink, photoinitiator migrates.

The 1 sentence every press shop owner should say: "Food packaging outer layer printing can only use 'food packaging dedicated ink', the unit price is 2-3x that of ordinary ink. If your budget is limited, I suggest switching to 'non-food-contact surface printing' (e.g., outer layer markings) + 'food-contact surface left blank'."

Source 2: Glue Migration Exceedance

3 common reasons for food packaging glue migration exceedance:

1) Solvent-based glue (oil-based glue): contains solvents such as toluene, xylene, ethyl acetate; solvent residues migrate to food. The most common pitfall: customer wants "high-strength bonding", press shop uses solvent-based glue, solvent residues exceed limits.

2) Water-based glue (acrylic glue / vinyl acetate glue): contains small amounts of free monomers (such as acrylic acid, vinyl acetate), may release in 50% ethanol simulant. The most common pitfall: customer wants "eco-friendly glue", press shop uses ordinary water-based glue, free monomers exceed limits.

3) Hot melt adhesive (EVA hot melt / polyurethane hot melt): contains plasticizers (such as phthalates), may migrate in olive oil simulant. The most common pitfall: customer wants "fast forming", press shop uses EVA hot melt, plasticizer exceeds limits.

The 1 sentence every press shop owner should say: "Food packaging glue is divided into 3 types: water-based glue (for water-based foods), PUR glue (for alcohol-containing foods), UV glue (for fatty foods). Tell me your food type, I'll recommend the corresponding glue."

Source 3: Lamination Migration Exceedance

3 common reasons for food packaging lamination migration exceedance:

1) EVA adhesive layer (ethylene-vinyl acetate copolymer adhesive layer): vinyl acetate monomer may release in 50% ethanol simulant. The most common pitfall: customer wants "matte lamination effect", press shop uses EVA adhesive layer, alcohol-type foods fail.

2) PU adhesive layer (polyurethane adhesive layer): contains free isocyanates (such as TDI, MDI), isocyanates may hydrolyze and migrate in distilled water simulant. The most common pitfall: customer wants "high-strength lamination", press shop uses PU adhesive layer, water-based foods fail.

3) Acrylic adhesive layer (pressure-sensitive adhesive): contains monomers such as butyl acrylate, may migrate in olive oil simulant. The most common pitfall: customer wants "peelable lamination", press shop uses acrylic pressure-sensitive adhesive, fatty foods fail.

The 1 sentence every press shop owner should say: "Lamination adhesive layer must match the food type: EVA for water-based foods, PU for dry foods, acrylic for dry foods. For alcohol or fatty foods, I recommend 'adhesive-free lamination' (such as co-extruded film)."

Source 4: Varnish Migration Exceedance

3 common reasons for food packaging varnish migration exceedance:

1) Water-based varnish: contains film-forming aids (such as ethylene glycol butyl ether), wetting agents (such as surfactants), aids may migrate in 4% acetic acid simulant. The most common pitfall: customer wants "matte effect", press shop uses water-based matte varnish, acidic foods fail.

2) UV varnish: contains photoinitiators (such as benzophenone, amine photoinitiators), reactive diluents (such as TMPTA), may migrate in olive oil simulant. The most common pitfall: customer wants "local UV varnish", press shop uses ordinary UV varnish, fatty foods fail.

3) Alcohol-soluble varnish: contains solvents such as ethanol, isopropanol, solvent residues migrate to food. The most common pitfall: customer wants "quick-dry varnish", press shop uses alcohol-soluble varnish, all food types may have residues.

The 1 sentence every press shop owner should say: "Food packaging varnish can only use 'food packaging dedicated varnish'; water-based varnish must be a food-grade product with ethylene glycol butyl ether content below 0.1%, and UV varnish must be a food-grade product with total photoinitiator content below 0.05%."

3 Real Exceedance Cases from Press Shops Submitting GB 31604 Series 9 Items

Case 1: Milk Tea Paper Cups (EVA Adhesive Layer Lamination → 50% Ethanol Simulant Fail)

Food type: milk tea containing edible alcohol (0.5-2% edible alcohol).

Press shop solution: water-based ink + water-based glue + EVA matte film + water-based varnish.

Test result: total migration in 50% ethanol simulant 8.5 mg/dm² (standard ≤ 10 mg/dm²), vinyl acetate monomer migration 0.05 mg/dm² (standard ≤ 0.01 mg/dm²), vinyl acetate monomer single item exceeded by 5x.

Remediation: switch lamination to adhesive-free co-extruded film (such as PE co-extruded film), unit price rose from 0.08 RMB/piece to 0.15 RMB/piece.

Customer's final choice: accepted 0.07 RMB/piece price difference, switched to co-extruded film, resubmitted and passed, delivered the entire batch of 100,000 cups on time.

Case 2: Chocolate Gift Box (Metallic Ink → 4% Acetic Acid Simulant Fail)

Food type: chocolate gift box containing cocoa butter.

Press shop solution: water-based ink + metallic ink (gold LOGO) + water-based glue + matte lamination.

Test result: lead migration in 4% acetic acid simulant 0.8 mg/kg (standard ≤ 0.05 mg/kg), lead single item exceeded by 16x.

Remediation: metallic ink switched to "food packaging dedicated metallic ink" (lead content below 0.005%), unit price rose from 0.05 RMB/piece to 0.18 RMB/piece.

Customer's final choice: metallic ink area was small (less than 5% of total printing area), switched to food-grade metallic ink, entire batch of 5,000 gift boxes remanufactured, delivered on time.

Case 3: Pastry Gift Box (UV Varnish → Olive Oil Simulant Fail)

Food type: pastry gift box containing butter.

Press shop solution: water-based ink + water-based glue + matte lamination + UV spot varnish (LOGO portion).

Test result: photoinitiator (benzophenone) migration in olive oil simulant 0.15 mg/dm² (standard ≤ 0.01 mg/dm²), benzophenone single item exceeded by 15x.

Remediation: UV varnish switched to "food packaging dedicated UV varnish" (total photoinitiator content below 0.05%), unit price rose from 0.03 RMB/piece to 0.10 RMB/piece.

Customer's final choice: accepted 0.07 RMB/piece price difference, switched to food-grade UV varnish, resubmitted and passed.

3 Most Common Migration Questions from Customers

Question 1: "Why didn't I have problems before with the same materials and processes?"

Answer: The 4 simulants for migration testing (distilled water, 4% acetic acid, 50% ethanol, olive oil) target different food types. Different food types correspond to different simulant test items: water-based foods use distilled water, acidic foods use 4% acetic acid, alcohol-containing foods use 50% ethanol, fatty foods use olive oil. If previous foods were all water-based foods, the 50% ethanol or olive oil test items wouldn't be triggered, so there wouldn't be problems.

Question 2: "Can I use cheaper ordinary ink and gamble on passing the test?"

Answer: No. Migration testing for food packaging ink is a mandatory national standard test item. GB 31604.1-2015 "National Food Safety Standard General Rules for Migration Testing of Food Contact Materials and Articles" specifies the test methods and limits for the 4 simulants. Migration from ordinary ink almost certainly exceeds limits (especially metallic and dye inks), and the cost of failing the test (remanufacturing + customer loss) is far higher than the price difference of food-grade ink.

Question 3: "How much more expensive is food-grade ink than ordinary ink?"

Answer: Food-grade ink unit price is 2-3x that of ordinary ink. Specific differences: water-based ink (ordinary 80-120 RMB/kg, food-grade 200-350 RMB/kg), metallic ink (ordinary 200-300 RMB/kg, food-grade 500-800 RMB/kg), UV varnish (ordinary 60-100 RMB/kg, food-grade 150-280 RMB/kg). For an order of 5,000 gift boxes, the food-grade material price difference is approximately 8,000-15,000 RMB.

The 1 Sentence Every Press Shop Owner Should Say

"Food packaging migration exceedance is not an ink problem—it's that all 4 sources (ink, glue, lamination, varnish) must be compliant. I suggest you first tell me the food type (water-based / acidic / alcohol-containing / fatty), and I'll give you a 'food type + material matching list', quote according to the list. If you only give me the four characters 'food packaging' without specifying the food type, I recommend you do small-sample testing first to confirm compliance, then mass production."

After saying this, customers will understand the real cost of food packaging migration compliance (food-grade material price difference + testing fees + remediation costs), and won't have disputes later over migration exceedance.

3 Improvements for Press Shop Quotes

Improvement 1: Food packaging orders should list "food-grade material price difference" separately on the quote. Customers must know the price difference for food-grade ink / glue / lamination / varnish, and cannot be quoted at ordinary packaging prices then have add-ons.

Improvement 2: Food packaging orders should note "small-sample testing recommended" on the quote. Recommend customers do small-sample testing at the proofing stage, cost 3,000-6,000 RMB, to avoid entire batch rework.

Improvement 3: Food packaging orders should note "migration compliance responsibility division" on the quote. Press shop is responsible for material compliance (producing with food-grade materials), customer is responsible for food type and testing result determination. Avoid subsequent compliance responsibility disputes.

The Zhejiang milk tea paper cup customer eventually came back to us. We redesigned the material solution for them (water-based ink + water-based glue + PE co-extruded film + water-based varnish), and simultaneously recommended they do all 4 simulants testing (4,500 RMB). They passed the test on first try, delivered the entire batch of 100,000 cups on time, with the unit price rising from 0.45 RMB/piece to 0.52 RMB/piece. The customer accepted the 0.07 RMB/piece price difference, saying "much better than the 300,000 RMB loss from the recall".

Further Reading

Food contact packaging GB 4806.1 to 4806.11 explained in one article, see Food Contact Packaging GB 4806.1 Explained in One Article. GB 4806.7 vs GB 4806.8 real press shop boundary, see GB 4806.7 vs GB 4806.8 Boundary. Food packaging 5 core standards (GB 4806.1/7/8/9/11), see Food Packaging 5 Core Standards.