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Views: 0 Author: Heming Paper Expert Ferrill Publish Time: 2026-11-11 Origin: heming-paper
Packaging converters and QSR food service buyers use the TAPPI T 559 Kit test, scaled from Kit 3 to Kit 12, to specify 100% virgin pulp, PFAS-free greaseproof paper. Under-specifying a Kit level causes oil seepage on fried foods, while over-specifying wastes procurement budget. Kit Level is a 1-12 grease resistance rating.
For most buyers, Kit 3-5 suits sandwich wraps. Kit 4-7 suits fries and fried chicken, and Kit 8-12 suits popcorn bags. Sheet weight runs from about 28 to 80 GSM across these grades.
GSM means grams per square meter, the weight of a sheet of paper, which says nothing by itself about how well it blocks oil. In food packaging, that gap between weight and barrier is where budgets leak. We show the grade and GSM for burgers, fries, pizza liners and popcorn bags.
Matching the grade to the food takes three inputs: fat load, temperature, and hold time.
Kit Level is a 1-12 rating of how well paper blocks oil.
Pick the lowest Kit Level that holds under your real conditions.
Kit 4-7 suits fries and fried chicken, and Kit 8-12 suits popcorn bags.
GSM is weight, not barrier, so a heavier sheet is not more greaseproof.
Kit Level does not measure steam or moisture resistance.
Run a hold test with your own food before a bulk order.
Ask for a written PFAS declaration, because the Kit number cannot prove PFAS-free status.
A Kit Level is a number from 1 to 12 that tells you how well a paper blocks oil. Higher numbers mean the paper resists more aggressive liquids, so a Kit 10 sheet holds out against oil that would soak through a Kit 3 sheet.
Think of sunscreen labels. A higher SPF gives stronger protection against one specific threat, and a higher kit level does the same for grease.
The number matters because a visible oil stain hurts your brand even when the food is fine. A customer who sees a dark spot on a bag often assumes the food is greasy or old. Nobody reads the stain as a packaging spec problem.
A stated Greaseproof Paper Kit Level replaces the vague label with a figure you can compare across suppliers. That comparison matters because two papers both sold as greaseproof can differ widely in rating. One may sit at Kit 3 while another reaches Kit 8, and they look almost identical in a sample pack.
In food packaging, a spec without a rating leaves the choice to whoever quotes the lowest price. Always ask a supplier for the number; never accept the word greaseproof alone.
The test works like a ladder: each rung is a harsher oil mixture, and the paper's rating is the last rung it survives. Labs apply numbered reagents from 1, the least aggressive, to 12, the most aggressive. Many people shorthand the method as TAPPI 559.
The official TAPPI T 559 test method was designed mainly to assess fluorochemical surface treatments. Film-like barriers and fluorine-free treatments may need extra evaluation. The highest-numbered reagent that does not stain the surface is reported as the Kit rating.
Step |
What happens |
Result |
|---|---|---|
Apply reagent 1 |
The mildest mixture sits on the surface for about 15 seconds |
Paper passes if no dark stain forms |
Step up |
The lab repeats with reagent 2, then 3, and so on |
Each pass moves one rung higher |
First stain |
A stronger reagent darkens the paper |
Testing stops at that rung |
Report |
The last reagent with no stain sets the rating |
Pass 6, fail 7 gives Kit 6 |
Each reagent sits on the surface for a fixed interval, typically 15 seconds. If a paper passes Kit 6 but fails Kit 7, the lab reports Kit 6. The result is a whole number, so a sheet never earns half a rung.
A rating ranks papers against one another, but it is not a time-to-leak figure. Treat the rating as a fair comparison tool, not a guarantee of hours of holdout.
A high Kit Level will not stop a soggy burger bun. Kit Level measures grease resistance under one controlled test condition and nothing else. Real packs also face food temperature, pressure, and hold time.
The test can compare barriers, but it does not indicate how long cooking oil takes to penetrate them. Two papers with the same number can last different lengths of time under a hot, heavy load.
A Kit Level does not tell you any of these things:
Steam or moisture resistance
Heat resistance in an oven or under a lamp
Wet strength when the sheet gets damp
Printability and ink hold
Soggy food from trapped steam needs venting, not a higher Kit. A tightly sealed wrap around a hot burger holds steam against the bun, and no oil barrier can fix that. Small vent holes or a loose fold let the moisture out.
When food turns soft, but the paper stays clean, look at ventilation before changing the grade.
The best Kit Level is the lowest one that stops stain-through under your real conditions. Kit 1-4 suits low-grease dry foods, Kit 5-8 suits moderately greasy foods, and Kit 9-12 suits high-grease fried foods.
The best greaseproof paper Kit Level for food is therefore set by fat load first. Then temperature and hold time move it up or down. The sections below match Kit Level to the actual food, with a GSM range for each.
Bread and pastries need Kit 0-3 at 28-38 gsm. Greaseproof paper for cookies sits in the same band, because plain cookies leave only a faint butter mark. Buttery shortbread may need the top of that range.
A higher grade for dry food only adds cost. Oil resistance beyond Kit 4 will not show on a bakery counter.
Burger and sandwich wraps use Kit 3-5 at 35-45 gsm. Burgers are the hard case in this band, since patty fat pools at the fold seam. A wrap needs an oil barrier that holds along the seam, not only on the flat face.
Fries and fried chicken take Kit 4-7 at 40-55 gsm. Popcorn bags need the top grades, Kit 8-12 at 50-80 gsm, because hot butter oil sits against the paper for a long time.
Fried foods stay hot and oily right up to the first bite. Add a small safety margin when food sits long or arrives hot.
A five-minute wrap-and-wait test with your own food tells you more than any data sheet. Hold the real food in the paper for the usual customer wait time, about 5-15 minutes, and look for stain-through.
Heat-lamp holding tests the worst case. If a sample survives there, it will usually survive a normal handoff at the counter.
Wrap the real food the way staff wraps it on a busy shift.
Hold it at service temperature.
Wait the usual customer time, 5-15 minutes.
Check the seams and the bottom for dark spots.
Record the result for each sample.
The common mistake is testing only a flat, cold sheet. Cold oil moves slowly, and a flat sheet has no folds, so almost any paper looks good. Test the same food, the same wrap, and the same time you will see in service.
Keep the passing sample as your reference for later lots.
Oil finds the weakest spot, and in wrapped food that spot is almost always a fold. A paper rated Kit 8 flat can behave closer to Kit 5 at a sharp crease. The lab test runs on a flat sheet, so it never sees that stress.
Folding crushes fibers, and a surface coating or a dense calendered layer can crack along the crease. Printing and die-cutting add more stress points. Each pass through a press or a die can weaken the sheet at the edges.
Ask the supplier to test the converted or folded sample, not only the flat roll. That shows the barrier performance you will actually get on the line.
Heavier paper does not mean more grease resistance. GSM measures weight, not barrier, so a lighter, highly calendered sheet can outrate a heavier, loosely built one. The paper weight tells you how stiff the sheet feels, and little else.
Choose GSM for stiffness and handling, and choose Kit Level for oil.
Greaseproof paper does not have to be plastic or fluorinated to reach a high Kit grade. Mills can make a strong grease barrier by physically compressing the fibers, a process called supercalendering, so the sheet carries no plastic film.
Rules have also moved away from fluorinated grease-proofers, known as PFAS. That shift matters for any food packaging spec written today.
The FDA announced in February 2024 that PFAS-containing grease-proofing substances for paper and paperboard food-contact uses were no longer being sold by manufacturers into the U.S. market. In January 2025, the agency determined that 35 food-contact notifications were no longer effective.
These substances once treated fast-food wrappers, microwave popcorn bags, take-out paperboard containers and pet food bags. Total-fluorine analysis detects fluorine but cannot tell PFAS from other fluorine substances.
Heming Paper is a subsidiary of Xianhe Corp. (SSE: 603733), with more than 1M tons of annual capacity in Quzhou, China. It describes its paper as 100% PFAS- and PFOA-free, made from 100% virgin wood pulp, and OBA-negative. It reaches up to KIT 12 through supercalendering and fluorine-free formulations, with zero PE, PLA, or wax coating.
Its heat range is 180-230°C (356-450°F). You can find wholesale PFAS-free greaseproof paper rolls and sheets from Heming Paper in several grade bands.
A Kit rating does not confirm PFAS-free status, so request these from suppliers:
A signed PFAS declaration
A lab test report
The Kit result for the exact grade
Ask for a PFAS declaration in writing, since the Kit number alone cannot prove it.
Greaseproof and parchment paper are not the same, though both resist oil to some degree. Parchment is usually silicone-coated for nonstick baking, while greaseproof paper blocks oil through dense fibers. In the US, greaseproof paper is often sold as grease-resistant paper or deli paper.
Wax and poly-coated sheets add a layer on the surface. Wax softens under heat and loses effectiveness above about 150°F (about 65°C).
Paper |
Barrier type |
Heat limit |
Best use |
|---|---|---|---|
Greaseproof |
Dense, supercalendered fibers |
180-230°C (356-450°F) for Heming grades |
Burgers, fries, bakery wraps |
Parchment |
Silicone coating |
Oven-safe for baking |
Lining pans and baking sheets |
Wax |
Wax layer |
About 150°F (65°C) |
Cold sandwiches and cold cuts |
Poly-coated |
Plastic film layer |
Film softens with heat |
Wet or saucy takeaway foods |
Poly coating blocks liquids well but also traps steam, so hot fried food can turn soft inside the pack. That is the ventilation trade-off to weigh before you pick it.
Pick wax only for cool or cold foods.
A good quote request fits in six lines. Each line should state a number or a requirement that every supplier can answer the same way.
Food and hold time, such as fried chicken held for 10 minutes
Minimum Kit Level per TAPPI T 559
GSM range
Converting needs, such as size, printing and die-cutting
PFAS declaration
Test report for each lot
The usual mistake is specifying GSM only. Suppliers then quote the cheapest sheet at that weight, and the grease barrier can be anything.
Give mechanical requirements too, since buyers who run fast lines need strength as well as barrier. Heming grades at Kit 4-7 in the standard mill grade, 40-55 gsm, list CD tensile of at least 1.7 kN/m and MD/CD tear of at least 200/220 mN.
Ask each supplier to quote the same Kit number and sample format.
Our range covers bread bags to popcorn bags in five grade bands. Each band pairs a Kit Level with a GSM range for a specific food.
Kit 0-3 at 28-38 gsm serves bread, pastries, and dry bakery bags. Kit 3-5 at 35-45 gsm serves burger wraps and deli sheets. Kits 4-7 at 40-55 gsm serve fries, fried chicken, and basket liners.
Kit 5-8 at 45-60 gsm serves pizza box liners and heavy takeaway wraps. Kit 8-12 at 50-80 gsm is a custom run for popcorn bags and high-fat pre-pack bags, with 50+ minutes of continuous hot oil holdout.
Every band comes as bleached white or unbleached brown kraft, made from ECF or TCF pulp. Because Kit 8-12 is a custom run, plan the order ahead of your launch date.
Request samples at the Kit and GSM that match your food before scaling up.
The right Kit Level is a number you specify, not a label you trust. Choose the lowest Kit that holds under real conditions, because extra grease resistance costs money and a shortfall costs customers.
Match the grade to fat load, temperature, and hold time, and treat the PFAS declaration as part of any food packaging spec. A rating on a data sheet is a starting point, not proof that your fold or your fryer will behave.
Your next step is simple: choose a Kit and GSM from the bands above, then run a hold test with your own food. Request a sample at the grade you choose today.
Yes, you can buy greaseproof paper as rolls or sheets from converters and packaging suppliers. Specify the Kit Level, the GSM, and a written PFAS declaration when you order, so every quote covers the same product. Sheet size, color, and printing also change an offer, so list them in your request.
Greaseproof paper is safe for food contact when it meets food contact rules. The FDA announced in February 2024 that PFAS-containing greaseproofers for paper food-contact uses were no longer being sold into the U.S. market. A written declaration from your supplier still confirms what the paper contains, which a Kit number cannot do.
French fries need Kit 4-7 for standard service. Fries that wait longer than the usual customer time, such as under a heat lamp, call for the upper end of that range or higher. Run a trial with your real fries and your usual oil level before you order in bulk.
No, a higher Kit Level is not always better. Extra barrier costs more, and dry foods like cookies gain nothing from it. Match the grade to fat load, temperature, and hold time, then add a small margin only for long holds or hot food that rides in a delivery bag.
No, Kit Level measures grease resistance only. The test uses oil-like reagents, not steam or water vapor. Soggy food usually points to trapped steam, so check venting, bag openings, and cooling time before you pay for a higher grade. A clean sheet with a soft bun means moisture, not oil.
No, heavier paper is not automatically more greaseproof. GSM is weight, while Kit Level is barrier, and a lighter, highly calendered sheet can outrate a heavier, loosely built one. Pick GSM for stiffness and handling, and check the Kit number for oil. Ask for both numbers on the data sheet.
