The right barrier for a food bag is the lightest one that keeps the bag clean with your food for your real holding time. Under-specify and a croissant bag spots after two minutes on the counter, or a fries bag goes translucent before the customer sits down. Over-specify and you pay for a coating, and often a recycling penalty, that dry rolls never needed. This comparison covers the main routes for portion bags: uncoated kraft, coated grease-resistant kraft, greaseproof paper (with glassine as a close relative) and PE-coated paper. It sits within the wider guide to custom printed paper food bags.
What are the main barrier options for paper food bags?
There are four practical options: uncoated kraft (no barrier), barrier-coated or treated grease-resistant kraft, true greaseproof paper whose resistance comes from the fibre itself, and PE-coated paper with a thin plastic layer. Glassine sits close to greaseproof as a dense, translucent alternative.
| Option | How grease resistance is achieved | Grease and oil | Moisture and sauce | Recycling with paper | Typical bag uses |
|---|---|---|---|---|---|
| Uncoated MG/MF kraft | None | Low; spots quickly | Low | Straightforward | Bread, rolls, dry snacks |
| Grease-resistant coated kraft | Water-based barrier coating or surface treatment on ordinary kraft | Medium to high, depends on coating and weight | Low to medium | Generally good for dispersion coatings; depends on coat weight and mill | Pastries, sandwiches, fries |
| Greaseproof paper | Heavily refined, densely packed fibres with very low porosity | High through the whole sheet | Low to medium; long wet contact weakens it | Clean paper generally repulpable; acceptance varies locally; rated red under the UK RAM for pEPR fees | Doughnuts, hot snacks, döner, fries cones |
| Glassine | Dense, refined and supercalendered fibres | Medium to high | Low | Generally accepted | Cookies, confectionery, small bakery items |
| PE-coated paper | Thin polyethylene layer extruded or laminated onto paper | Very high | High | Harder; PE must be separated during pulping | Sauce-heavy food, long holds, delivery |
German specifications often separate "fettdicht" (greaseproof, resists penetration) from "fettabweisend" (grease-repellent, delays it). Asking which one a quotation means avoids comparing unlike papers. Coating chemistries, including water-based dispersions, PLA and wax, are explained in barrier coatings for paper packaging.
How is grease resistance measured, and what KIT rating does a food bag need?
Grease resistance is commonly reported as a KIT rating, where a series of numbered oil and solvent mixtures is applied to the paper and the highest number that does not stain through is recorded; higher numbers mean better resistance. Moderately fatty bakery and snack items are often handled with mid-range KIT values, and hot, oily foods with higher ones.
Two cautions when comparing quotations:
- KIT is a surface test on flat paper. Bags fail first at folds, creases and glued seams, where a coating can crack and refined fibres are stressed.
- Real food combines fat with heat, moisture and time. A paper that passes a high KIT level can still fail with hot, wet, sauced food.
The test method, typical scales and what KIT does not tell you are covered in KIT test and grease resistance ratings explained. For a bag, treat KIT as a screening value and confirm with your own product.
Which barrier should you choose for each type of food?
Pick the lowest barrier that keeps the bag clean for your real holding time: uncoated for dry items, grease-resistant or greaseproof for fatty and fried items served quickly, and PE-coated only when sauce, steam or long delivery times would beat a paper-only barrier.
| Food | Fat / moisture | Typical holding time | Usual choice | Watch-outs |
|---|---|---|---|---|
| Bread rolls, loaves, dry pretzels | Low / low | Hours | Uncoated kraft | Over-specifying adds cost on high-volume sizes |
| Croissants, Danish, butter pastries | High fat / low moisture | Minutes to hours | Grease-resistant or greaseproof | Butter migrates through folds over time |
| Doughnuts, churros, glazed items | High fat and sugar | Minutes | Greaseproof or glassine | Sugar glaze sticks to some coated surfaces |
| Fries, chips, fried snacks | High oil, some steam | Minutes | Greaseproof or grease-resistant cone or flat bag | Steam softens paper if the bag is closed |
| Warm sandwiches, toasties | Medium fat, some moisture | Minutes to an hour | Grease-resistant, sometimes window bag | Condensation inside if bag is sealed |
| Döner, kebab with sauce | High fat, wet sauce | Minutes (eat-in-hand) to 30+ minutes (delivery) | Greaseproof for quick service; PE-lined for wet sauce or delivery | Sauce pools at the bag bottom |
| Fish and battered foods | High oil, steam | Minutes | Greaseproof, often with an inner wrap | Steam load; consider venting |
For döner and kebab specifically, grade-by-grade guidance is in the kebab and döner bags guide.
Are grease-resistant food bags PFAS-free?
They need to be for the EU and many US states, but treat it as a specification to confirm with test data for each grade rather than an assumption. For the EU, the PPWR (Regulation (EU) 2025/40) sets PFAS limits for food-contact packaging from 12 August 2026: 25 ppb for any single PFAS, 250 ppb for the sum of targeted PFAS, and 50 ppm for all PFAS including polymeric PFAS. In the US, PFAS grease-proofing agents are no longer sold for food contact and many states ban intentionally added PFAS in food packaging.
Fluorochemical treatments were historically a cheap way to make thin kraft resist grease, which is why food bags are a focus of these rules. Today the alternatives are mechanical (refined greaseproof fibre), water-based dispersion coatings, and PE or other polymer layers.
What to ask a supplier for:
- A written statement that no PFAS are intentionally added to the paper, coating or inks.
- For EU supply, test results for targeted PFAS and total fluorine on the barrier paper.
- For US states using total organic fluorine thresholds, the relevant test value.
Rules, test methods and state-by-state dates are in the PFAS-free food packaging guide. This is general information, not legal advice.
What are the trade-offs of PE-coated food bags?
PE-coated food bags give the best grease and moisture resistance, but they are harder to recycle with paper, can be classified as single-use plastic products under EU rules, and may attract extra fees or restrictions depending on the market. Use them where performance genuinely requires it rather than as a default.
The specifics to weigh:
- Recycling: many paper mills can separate thin PE layers, but not all accept them; PE-coated paper needs more processing and some local schemes direct it away from paper collection.
- EU Single-Use Plastics Directive: the Commission's 2021 guidelines treat paper products with a plastic lining or coating as single-use plastic products. Packets and wrappers for food eaten directly from them are a SUP category with extended producer responsibility, including litter clean-up costs.
- PPWR: the Commission's guidance notice of 5 June 2026 (C(2026) 3702), which is not legally binding, treats paper-based packaging containing 5 % or more plastic as covered by the Annex V restrictions on single-use plastic packaging from 1 January 2030, which apply to dine-in use rather than takeaway, so check the plastic share of a PE-coated specification before committing to it long term.
- Germany: the single-use plastic fund (Einwegkunststofffondsgesetz) charges a levy per kilogram on in-scope single-use plastic products placed on the German market, paid by the first placer; whether a given PE-coated bag is in scope should be confirmed for your product. See packaging compliance in Germany and Austria.
- UK: under packaging EPR (pEPR), the recyclability assessment methodology (RAM) rates greaseproof, siliconised and waxed paper red, the highest modulated fee band, in RAM v1.1 and in RAM 2027, which defines the category as fibre densification or a continuous wax or silicone layer. A PE-coated bag with more than 5 % plastic is assessed as fibre-based composite, which carries a higher fee per tonne than paper and board. The rating sets the UK producer's fee; it does not say whether a council collects the bag. Glassine is also a densified paper, so confirm how your assessment classifies it. See UK packaging regulations.
Where a PE coating is used only to cope with occasional sauce, a greaseproof bag combined with a separate inner wrap from the custom printed greaseproof paper range can sometimes avoid it.
Does the barrier affect printing on food bags?
Yes. Uncoated MG kraft takes water-based flexo inks readily on its glazed side; greaseproof and glassine are smooth and dense, so inks sit on the surface and need suitable formulations and drying; barrier-coated surfaces can change how ink wets and adheres. Printing is normally on the outside of the bag, with the barrier facing the food.
Two practical points:
- Heavy solid ink areas on thin barrier paper can slow drying and increase the risk of set-off onto the food-contact side when the reel is wound or bags are stacked. Food-contact print rules under Regulation (EC) 2023/2006 require that this transfer is prevented.
- Grease show-through is more visible on white paper and pale colours. A darker colour field or an all-over pattern makes slight spotting less noticeable, which can let you use a lighter barrier.
How should you test grease-resistant bags before ordering?
Test samples with your own food, at serving temperature, for your longest realistic holding time, and look at folds, seams and the bottom of the bag rather than the flat face. A barrier that works on the face but fails at the crease will still mark the customer's hands.
A simple in-store test:
- Fill sample bags with the fattiest and wettest items on the menu, straight from the fryer or oven.
- Fold or close them the way staff actually do.
- Leave them for the realistic time: counter wait, walk home, or delivery time.
- Check the outside surface, folds, side seams and bottom fold for spotting, softening and translucency.
- Repeat on a warm and a cold day if bags are stored in non-climate-controlled areas, since paper behaviour changes with humidity.
Record the results against each paper option so the final choice is based on your food, not on a catalogue rating. Sampling and approval steps are covered in packaging sampling, pre-production approval and quality control.
Barrier specification checklist
When you request a quotation for grease-resistant food bags, state:
- The foods each bag must hold, their temperature and fat or sauce content.
- Longest holding time (counter, takeaway walk, delivery).
- Preferred route: greaseproof, coated grease-resistant, glassine or PE-coated, or "supplier to recommend".
- Any target KIT level, understood as a screening value.
- PFAS-free requirement and target markets for test data.
- Recycling or plastic-free requirements from your own sustainability policy.
- Print colours and coverage, so ink and drying can be matched to the barrier paper.
Bring this to the custom printed paper food bags overview to complete the format and size choices, or send the barrier brief for a quotation.