📌 Key Takeaways
Soggy food happens when paper specs don’t match your menu—fix the numbers, fix the complaints.
- Two Numbers Tell the Story: GSM measures paper thickness and strength; Kit Level measures grease resistance—you need both to prevent soggy wrappers.
- Diagnose Before You Switch: Damp, collapsed wrappers signal a steam problem; greasy spots mean oil is bleeding through—different causes need different fixes.
- Heavier Paper Won’t Save You: A thick 70 gsm sheet still leaks grease without the right Kit rating, so weight alone doesn’t solve oil problems.
- Ask Suppliers for Proof: Request Kit test results tied to the actual production batch you’re buying—not just a general certificate from years ago.
- Run Kitchen Trials First: Wrap a sample item, hold it for your typical service time, and check at 5, 10, and 20 minutes before committing to full inventory.
Match the spec to the menu, and soggy complaints disappear.
Food service operators and packaging buyers will find practical spec templates and supplier questions here, preparing them for menu-specific paper selection that follows.
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Grease on their hands. A soggy bottom. Another complaint.
The customer holds up the wrapper—burger bun fused to the paper, fries stuck to the liner. Your line cook shrugs and reaches for a second sheet. We’ll double-wrap it next time. But double-wrapping costs time, wastes materials, and still doesn’t fix the problem.
This isn’t about cheap paper. It’s about paper that wasn’t specified for the job.
Grease Resistance and GSM Specs define the paper’s physical weight (GSM) and its chemical ability to repel oil (Kit Level). GSM is the “muscle” (thickness), while Kit Level functions as the chemical barrier against lipid migration.
When you understand these two numbers, you stop chasing complaints with workarounds. You start specifying paper that actually performs for your menu, your hold times, and your service conditions.
The Real Reason Food Goes Soggy in Paper Packaging
Soggy food is a failure of specification, not just paper quality.
Here’s what’s actually happening inside that wrapper. Hot food releases moisture as steam. Fried food releases oil. Both attack paper—but through completely different mechanisms that require different solutions.
Steam condenses when trapped against a cooler surface, turning paper damp from the inside out. The wrapper goes soft, collapses, and fuses to the food. Oil behaves differently: it wicks through gaps in the paper fibers, creating translucent grease spots that eventually soak through to the customer’s hands.
The trap most operators fall into: assuming heavier paper solves both problems. A thicker sheet might feel sturdier, but if it lacks grease resistance, oil still bleeds through. And if it’s too dense to let moisture escape, steam pools against the food and creates that gummy, collapsed wrapper nobody wants to open.
Sometimes the problem isn’t even the paper itself. Delivery time, stacked hot items, and humidity can turn a “fine” wrap into a soggy failure. Line staff often respond by double-wrapping or swapping liners on the fly—a workaround that costs money without addressing the root cause.
The common misdiagnosis: blaming GSM alone when the real culprit is grease resistance or steam venting. Before changing suppliers or upgrading specs, identify whether you’re fighting steam, grease, or both. One tradeoff matters early: stronger grease barriers can sometimes reduce breathability. If steam is the main enemy. The goal is not the maximum barrier—the goal is the right balance for the menu and the hold time.
GSM in Plain English: What It Measures and What It Doesn’t
GSM stands for grams per square meter—a standardized way to describe paper weight. The measurement follows ISO 536, which means a 50 gsm sheet from one supplier should weigh the same as a 50 gsm sheet from another.
This ensures cross-vendor consistency, as GSM directly correlates with the cross-directional (CD) stiffness and tensile strength required for high-speed folding. Higher GSM generally means stiffer paper that holds its shape during folding, survives handling on a busy line, and resists tearing when you tuck the corners of a wrap.
Practical GSM ranges for food service:
- 25–40 gsm: Lightweight sheets for dry baked goods, interleaving, basic sandwich wraps
- 40–55 gsm: Mid-weight wraps for burgers, breakfast sandwiches, moderate-grease items
- 50–70 gsm: Heavier sheets for fried chicken, wings, items needing structural support during delivery
For operations sourcing kraft paper as a base substrate, these GSM bands provide a starting framework for matching weight to application stress.
Here’s where operators get tripped up: higher GSM doesn’t automatically mean better grease resistance. A 70 gsm uncoated kraft paper might feel impressively sturdy, but hot oil will wick right through it. You can have all the structural muscle you need and still end up with grease on the customer’s hands.
Think of GSM as the paper’s skeleton. It determines whether the wrap can do the physical work—folding quickly, holding a crease, surviving the pass from kitchen to customer. But the skeleton alone won’t stop oil from migrating through the fibers. That requires a different property entirely.
For deeper background on how GSM relates to paper strength and handling characteristics, see Paper Bag Raw Material Grades: GSM and Burst Factor Explained and Understanding GSM and Burst Factor: A Specifier’s Guide to Paper Bag Strength.
Kit Levels: The Grease-Resistance Rating Operators Rarely Ask For
Is kit level just a marketing term? No—it’s a standardized, testable measure of how well paper resists oil penetration.
The test method, commonly referenced as TAPPI T 559, applies a series of increasingly aggressive oil-and-solvent mixtures to the paper surface. The highest-numbered mixture that doesn’t penetrate within a set time becomes the paper’s kit rating.
The scale runs from 1 to 12:
- Kit 1–3: Minimal oil resistance. Lightly treated or sized papers fall here (untreated raw kraft often has no resistance, or Kit 0). Acceptable for dry baked goods and sandwiches without heavy sauces or oily dressings.
- Kit 4–6: Moderate resistance. Works for burgers, light fried items, foods with some grease but shorter hold times.
- Kit 7–9: Strong resistance. Required for fried chicken, french fries, wings—anything with significant surface oil that sits for several minutes before serving.
- Kit 10–12: Maximum resistance, traditionally achieved with fluorochemicals, but increasingly matched by advanced PFAS-free barrier coatings (though testing methods for these may vary). Essential for high-fat delivery items, particularly where local regulations restrict fluorinated chemistry.
A common misconception: wax paper works for all hot foods. Standard wax paper typically rates kit 1–3, making it suitable for cold or dry items but insufficient for anything releasing significant grease. High-fat foods like fried chicken or bacon burgers require kit 6–9 to prevent oil soak-through.
The critical limitation to understand: kit level measures grease resistance, not steam management. A kit-9 greaseproof paper can still turn soggy if steam has nowhere to go. Steam management requires balancing barrier properties with breathability for hot foods. This is the insight many operators miss—a stronger grease barrier can actually fail if breathability is ignored, because trapped steam condenses and soaks the paper from within.
When requesting quotes from food packaging paper suppliers, ask for kit level results and the test method used. A supplier who can provide documented kit ratings demonstrates quality control. One who can’t tell you the kit rating probably hasn’t tested it.
Quick Triage: Is the Enemy Steam, Grease, or Both?
Before changing specs, diagnose the actual failure mode. Treating a steam problem with a grease solution—or vice versa—wastes money and won’t fix the complaint.
Signs pointing to steam: The paper feels damp or clammy without visible oil stains. The wrapper has collapsed or turned soft and gummy. The food surface is wet, not greasy. Problems worsen with longer hold times in closed containers or stacked packaging. Failure is worse when wraps are tightly sealed, and it gets noticeably worse with delivery hold time.
Signs pointing to grease: Translucent spots appear where oil has wicked through the fibers. Grease transfers to hands when handling the package. The wrapper looks stained but hasn’t structurally collapsed. Failures concentrate on surfaces directly touching fried food. Problems cluster around fried foods and fatty proteins.
Signs pointing to both: The paper is both damp and grease-stained. You’re serving hot fried food in sealed or stacked packaging. Delivery runs are long enough for both steam condensation and oil migration to occur.
Service conditions matter enormously. A burger eaten in the dining room after two minutes behaves differently than the same burger delivered after fifteen minutes in a closed bag. The same wrapper that works perfectly for dine-in service may fail completely for delivery.
For steam-dominant problems, the fix often involves breathability—vented containers, perforated liners, or paper with enough porosity to let vapor escape. For grease-dominant problems, the fix is a higher kit level or a barrier coating. For both, you need paper that balances resistance with breathability, or you need to modify packaging design: vents, separate compartments, shorter hold times.
Menu-to-Spec Matching Table
The table below provides starting-point recommendations for common food service items. These represent generally accepted ranges based on food characteristics and typical service conditions—not universal rules. Actual performance depends on your specific hold times, temperatures, packaging design, and storage conditions. Use these as a baseline, then validate with kitchen trials.
| Menu Item | Primary Failure Mode | Suggested GSM Range | Minimum Kit Level | Notes |
| Burgers (wrapped) | Grease + steam | 40–60 gsm | Kit 6–8 | Loose fold or vented wrap helps steam escape; increase kit for bacon/cheese variants |
| Fried chicken pieces | Heavy grease | 50–70 gsm | Kit 8–10 | Higher GSM for structural support; high kit critical for oil-soaked skin |
| French fries (liner) | Grease + steam | 35–50 gsm | Kit 7–9 | Perforated or vented liner reduces steam buildup |
| Deli sandwiches | Light grease, some steam | 30–45 gsm | Kit 3–5 | Lower barrier needs unless heavy mayo/oil dressings |
| Pastries/baked goods | Minimal grease | 25–40 gsm | Kit 1–3 | Butter-rich items may need kit 4–5 |
| Pizza slices (liner) | Grease + cheese oil | 40–60 gsm | Kit 6–8 | Cheese oil is aggressive; allow breathability |
| Tacos/burritos | Steam + sauce moisture | 35–50 gsm | Kit 4–6 | Saucy fillings create internal moisture |
| Wings (basket liner) | Heavy grease + sauce | 50–70 gsm | Kit 8–10 | Sauced wings compound grease load |
| Breakfast sandwiches | Grease + steam | 40–55 gsm | Kit 5–7 | Egg creates steam; bacon/sausage add grease |
| Fish and chips | Heavy grease + steam | 50–70 gsm | Kit 8–10 | Battered fish releases significant oil |
These specifications assume typical hold times of 5–15 minutes. Delivery operations with 20–30 minute transit times may need higher kit levels or modified packaging to prevent failure. Always verify food-contact compliance documentation for your market before finalizing specifications.
How to Write a Spec a Supplier Can Quote
Vague requests produce incomparable quotes. “Greaseproof paper for burgers” tells the supplier nothing specific—you’ll receive whatever they want to sell. A proper specification request yields quotes you can actually compare and documentation you can verify during a health inspection or compliance audit.
Essential elements for your spec request:
GSM target and tolerance: State the grammage you need and the acceptable range. Example: “50 gsm ±5%.” This ensures that a±5% tolerance (47.5–52.5 gsm) is strictly enforced, preventing the substitution of lighter 45 gsm stocks. Ask how they verify grammage—reputable suppliers test to ISO 536 or equivalent and can provide grammage test documentation.
Kit level target: Specify the minimum kit rating required. Example: “Minimum kit level 7 per TAPPI T 559 or equivalent.” Request recent test results tied to the production lots you’ll actually receive—not just a general certificate from a past batch.
Substrate and coating requirements: Clarify the base material (kraft, bleached, unbleached, recycled content) and any barrier coating needs (poly, wax, or specify fluorochemical-free if required by your market’s regulations). For guidance on selecting between virgin and recycled substrates, see Virgin vs. Recycled Kraft Paper: Choosing the Right Grade for Paper Bag Durability.
Use case description: Describe the application: “Wrapping hot burgers, hold time up to 10 minutes, some items delivered in closed bags for 15–20 minutes.” This context helps suppliers recommend appropriate specs and flag potential issues before you order.
Food-contact compliance: Request documentation confirming the paper meets food-contact requirements for your market. FDA compliance for the US, EU food-contact regulations for Europe—don’t assume. The workflow in Navigating Specific Migration Limits (SML): A Global Compliance Workflow for Food-Grade Packaging Paper explains why a ‘pass’ in one market may be irrelevant in another. Request specific Declarations of Compliance (DoC). These are mandatory for regulatory audit trails and liability protection—the verification workflow in How to Verify Food Contact Compliance Beyond Certificates: A Supplier Shield Model explains why certificates alone are insufficient.
A Simple Spec Template for Supplier Requests:
Use case: Hot wrap/liner for [menu item]. Typical hold time: ___ minutes. Dine-in / delivery: ___.
Structure (GSM): ___ gsm target, ± ___% tolerance (confirm grammage method; ISO 536 is a common reference).
Grease Resistance (Kit): Minimum Kit ≥ ___, verified using a kit test reference such as TAPPI T 559 (or equivalent lab reporting).
Format: sheets/rolls, size, ply, print requirements if applicable.
Evidence Request: Provide the most recent grammage and kit test results tied to the production lot being delivered.
The combination of lot-tied evidence plus kitchen trial validation is practical even for small operators.
Supplier-Request Checklist:
- GSM target + tolerance, and verification method
- Kit level result and test method used
- Whether test results are tied to current production lots
- Food-contact compliance documentation for your intended market
- Lead time and minimum order quantity
A supplier who can answer these questions demonstrates quality control and reliability. One who can’t may not have the systems to ensure consistent performance batch after batch. For a structured approach to evaluating supplier responses, see Seven Questions to Ask a New Supplier (That Scammers Can’t Answer).
For guidance on building detailed spec sheets, see Creating Your Mill Spec Sheet: A Guide for Converting Operations Managers or the step-by-step workflow in How to Create Your Mill Spec Sheet: A Step-by-Step Guide.
Operational Checks to Prevent Repeat Soggy-Food Incidents
Specifications on paper mean nothing if performance drifts after delivery. Build simple verification into your receiving and kitchen routines.
At receiving: Verify that GSM matches your order—some suppliers include it on packaging, or you can weigh a known-size sample. Check for shipping damage: moisture exposure during transit can compromise paper performance before you even open the case. Keep one sheet as a retained sample from each lot for quick comparisons when complaints occur. If suppliers provide test reports, file them by lot number so documentation is easy to retrieve.
Storage matters: Paper absorbs moisture from the environment, which degrades barrier properties over time—the relationship between moisture and performance is explored in Moisture Windows: Why ‘Within Range’ Matters More Than Absolute Values for Kraft Paper Converting. Keep packaging off the floor and away from wet walls or steam sources. Avoid storing near ovens, dishwashers, or open prep areas where moisture is constant. Rotate stock so older cases are used first. A case that performs well in week one can underperform in week six if storage conditions allow humidity to creep in.
In the kitchen: Run a quick trial when you receive a new lot or switch suppliers. Wrap a sample item at the same temperature and portion size used in service, hold it for your typical service time (including bagging and stacking if that happens), and check at intervals—5, 10, 20, and 30 minutes—scoring structure and grease-through separately. This fifteen-minute investment can prevent a week of customer complaints. Train line staff on proper wrapping technique—loose folds let steam escape while tight seals trap moisture against the food.
Tracking and refining: Log soggy-food complaints by menu item and time of day. Look for patterns. Track the item, daypart, whether it was dine-in or delivery, approximate hold time, and the primary symptom (steam limpness, grease-through, or both). Is one item consistently failing? Does the problem worsen during delivery rush hours? Does it correlate with a specific paper lot? Use complaint data to refine specifications over time. If fries fail at 15-minute delivery times but perform fine for dine-in, you may need a higher kit level specifically for delivery orders—or a switch to vented packaging.
Kitchen trials and receiving checks won’t replace formal testing, but they provide practical quality control. If a new lot performs noticeably worse than the previous one, you have grounds to request test documentation or reject the shipment.
For more on incoming material verification, see Testing Protocols: How to Verify Kraft Paper Quality Upon Arrival.
Pitfalls: Over-Spec, Under-Spec, and Misdiagnosis
Over-specifying costs money without solving problems. A kit-10 barrier wrap for a dry croissant is expensive overkill. Worse, if the barrier is too aggressive for the application, it may trap moisture and create the sogginess you were trying to prevent. Higher specs also mean higher case prices. Match the specification to actual food characteristics and hold conditions—not to a general fear of complaints.
Under-specifying creates the complaints driving you to read this guide. If your fries bleed grease through the liner, a kit-4 paper won’t cut it regardless of how many times line staff double-wrap. Under-spec also generates hidden costs: wasted liners, staff time on workarounds, customer complaints that damage brand reputation, and the stress of never quite trusting your packaging to perform.
Misdiagnosis is the subtlest and most expensive trap. Blaming GSM when the real problem is grease resistance leads to buying heavier paper that still fails. Blaming the paper when the real problem is packaging design—no venting, excessive stacking, unrealistic hold times—leads to endless supplier switches that never fix the issue. Blaming the supplier when the real problem is storage conditions that degraded the paper before use creates adversarial relationships without improving outcomes.
Before changing specs or switching suppliers, return to the diagnostic framework. Identify whether steam, grease, or both are causing the failure. A clear diagnosis leads to a targeted fix. A guess leads to another expensive round of trial and error.
Build a Simple Spec Sheet for Each High-Risk Item
Soggy food isn’t inevitable. It’s a symptom of specifications that don’t match your menu’s actual demands.
You now have a framework to fix it. GSM provides the structural muscle—stiffness, fold behavior, durability. Kit level provides the grease shield—oil resistance matched to fat content. Together, these two numbers give you a simple, testable specification for each high-risk menu item.
Technical procurement eliminates the guesswork inherent in off-the-shelf packaging selection. They specify it with two numbers, a clear use case, and documentation they can verify. When packaging performs consistently, complaints drop, waste decreases, and the guest experience stays protected.
Your next steps:
Start by identifying your three highest-complaint menu items. Use the triage framework to diagnose whether each failure comes from steam, grease, or both. Reference the menu-to-spec table for starting-point specifications. Write a proper spec request using the checklist and template, and ask suppliers for test documentation tied to current production lots. Run kitchen trials before committing to full inventory.
For more operator-focused guides on food grade packaging paper selection criteria, explore PaperIndex Academy. When you’re ready to source paper that meets your specifications, you can browse food packaging paper suppliers by region and product category, or submit an RFQ and receive quotes free from multiple suppliers to compare options directly.
Frequently Asked Questions
What GSM should be used for burger wraps?
A common starting point is 45–55 gsm with Kit 7–9, then validated under real hold time—especially for delivery. GSM supports structure and handling while the kit targets grease-through. Final numbers can vary with paper construction and folding method, so a short hold-time trial remains the safest confirmation.
What kit level prevents grease-through?
No single universal kit number exists. Higher-fat foods and longer hold times generally require higher kit performance. The practical approach is to set a minimum kit level based on the menu-to-spec table, confirm it using a kit test reference such as TAPPI T 559, and validate against the oiliest, hottest version of the menu item.
Why does food go soggy even with greaseproof paper?
Because “greaseproof” addresses oil migration while sogginess is often driven by steam condensation. If the wrap format traps moisture, the paper can turn limp even when grease doesn’t leak. Solving steam issues often involves venting and breathability choices alongside GSM—not simply adding more barriers.
Is kit level just a marketing term?
Kit level is tied to standardized kit testing for grease resistance, commonly referenced under TAPPI T 559. The key is asking for the test method used and requesting results tied to the production lot being delivered, rather than accepting an unverified claim.
How can a small operator verify claims without a lab?
Use a two-step approach: request supplier evidence (GSM/grammage verification and kit results tied to a lot), then run a short kitchen hold-time trial using real service conditions. This combination catches the two most common problems—paperwork that doesn’t match production, and lab ratings that don’t reflect the actual menu.
Resources
- TAPPI T 559 — grease resistance testing for paper and paperboard
- ISO 536 — grammage (GSM) determination for paper and board
- KIT grease resistance method explainer (Measurlabs)
- Smithers grammage testing
Disclaimer:
This article is educational information only.
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