Cupstock and Greaseproof Paper: A Technical Buyer's Guide to Food-Safe Paper Packaging

Food packaging is one of the most technically demanding segments of the paper industry. The paper must be safe for food contact, resistant to grease or moisture, strong enough to hold hot liquids or heavy contents, and compatible with high-speed converting equipment. A single specification gap — the wrong grammage, an insufficient KIT rating, or a missing compliance document — can disrupt an entire production run.

This guide covers four essential food-grade paper and board categories: cupstock board, greaseproof paper, PE coated paper, and silicone coated paper.

Cupstock Board: The Foundation of Paper Cups

Cupstock board is a virgin-fibre paperboard developed specifically for paper cup manufacturing and food container converting. It must deliver reliable forming performance on high-speed cup-making machines while providing a clean surface for food-service branding and graphics.

Technical Specifications

Choosing the Right Grammage

Cup grammage selection depends on cup size, contents, and whether the cup is for hot or cold beverages:

• 160–190 gsm: Small cups (4–8 oz), typically cold drinks
• 210–250 gsm: Medium cups (8–16 oz), hot and cold beverages
• 260–330 gsm: Large cups (16–24 oz), heavyweight hot cups, and food containers

Higher grammage provides more insulation and rigidity but increases material cost and cup weight. The optimal grammage balances structural performance with cost efficiency for the specific cup format.

PE Coating Options

Cupstock can be supplied uncoated for in-house PE coating, or with single-side or double-side PE coating applied. Single-side PE coating (inside the cup) provides liquid barrier for cold drinks. Double-side PE coating (inside and outside) is typically used for hot drinks to prevent condensation from softening the outer surface.

For buyers who manage PE coating in their own converting process, uncoated cupstock base board is the standard supply form. For buyers who require ready-to-convert PE-coated board, coated options are available subject to order specifications.

Key Converting Properties

• Forming performance: The board must form clean cup sidewalls without cracking, splitting, or delamination at high machine speeds.
• Printing surface: The outside surface should accept flexographic or offset printing for brand graphics.
• Sealing behavior: The PE coating must heat-seal reliably at cup-forming temperatures.
• Rim curl: The top edge must curl cleanly to form the drinking rim without tearing.

Applications

• Hot drink cups (coffee, tea)
• Cold drink cups (soft drinks, iced coffee, smoothies)
• Food containers (soup, noodles, salad bowls)
• Ice cream cups and tubs
• Takeaway packaging

Greaseproof Paper: Barrier Without Coating

Greaseproof paper achieves oil and grease resistance through intensive fiber refining (mechanical treatment), not through chemical coating. The highly hydrated and fibrillated fibers create a dense, closed sheet structure that physically blocks grease penetration — a different mechanism from PE-coated or chemically treated papers.

Technical Specifications

Understanding KIT Ratings

The 3M KIT test is the standard method for measuring grease resistance in paper. It uses a series of 12 test solutions (KIT 1 through KIT 12) with increasing aggressiveness. A higher KIT number means better grease resistance.

For food-service applications:

• KIT 5–6: Suitable for dry or low-grease foods (bread, pastries, cookies)
• KIT 7–8: Suitable for moderate-grease foods (burgers, sandwiches, fried chicken)
• KIT 9+: Suitable for high-grease foods (fries, oily snacks, cheese)

YOUNGSUN greaseproof paper is rated at KIT level 6 or higher for the referenced grade. Buyers with specific KIT requirements should specify the target level when requesting a quotation.

White vs. Natural Greaseproof

• White greaseproof: Bleached for a clean, bright appearance. Preferred for bakery wrapping, branded food-service packaging, and applications where food visibility matters.
• Natural greaseproof: Unbleached, maintaining the natural brown fiber color. Preferred for eco-branded packaging, rustic or artisanal food presentation, and sustainability-focused brands.

Converting and Printing

Greaseproof paper can be:

• Cut to sheet or roll format
• Printed with flexographic or offset methods (pre-print or post-print)
• Folded, wrapped, or bag-formed
• Interleaved between food layers

Custom printing is available for branded sheets, wraps, and bags — a key value-add for QSR chains and food-service brands.

Applications

• Bakery wrapping (pastries, bread, croissants)
• Burger and sandwich wraps
• Fried food liners and baskets
• Takeaway bags and pouches
• Tray liners for food service
• Confectionery wrapping
• Food interleaving (separating layers of cheese, meat, or pastry)

PE Coated Paper: Barrier by Lamination

PE coated paper consists of a paper or board substrate extrusion-coated with a layer of polyethylene on one or both sides. The PE layer provides moisture resistance, liquid barrier performance, and heat-sealing capability — properties that the paper substrate alone cannot deliver.

Common Configurations

• Single-side PE coated: Barrier on one face. Used for wrap materials, cup stock (when only the inside needs liquid barrier), and general moisture-resistant packaging.
• Double-side PE coated: Barrier on both faces. Used for cups (hot drinks), food containers, and applications requiring both internal liquid barrier and external condensation resistance.

Substrate Options

PE coating can be applied to different paper and board substrates depending on the application:

• Cupstock board for paper cups
• Kraft paper for wraps and bags
• White paperboard for food containers

Heat-Sealing Performance

One key advantage of PE coated paper is heat-sealing capability. Under heat and pressure, the PE layer melts and bonds to itself, creating a strong, leak-proof seal. This is essential for cup side-seam sealing, lid attachment, and pouch or bag forming.

Silicone Coated Paper: Non-Stick Release Performance

Silicone coated paper — also called silicone release paper or non-stick baking paper — has a silicone coating applied to one or both sides, creating a surface that food, adhesive, or other substances will not stick to.

Key Properties

• Non-stick surface: Food releases cleanly without oil or grease.
• Heat resistance: Suitable for baking temperatures (typically up to 220°C / 428°F).
• Moisture resistance: The silicone layer provides moisture barrier in addition to release performance.
• Reusable: Depending on application and care, silicone coated paper can be used multiple times.

Applications

• Baking paper and parchment
• Food wrapping for sticky or moist products
• Release liners for adhesive labels and tapes
• Industrial release applications

Food Safety Certifications and Compliance

For international buyers, food-contact compliance documentation is essential. Different markets have different regulatory frameworks:

When sourcing food-grade paper and board, always:

1. Specify the target market and required compliance standard
2. Request the relevant compliance documentation from the supplier
3. Confirm whether the compliance covers the base paper, the coating, or both
4. Verify that compliance is valid for your specific food type (fatty, aqueous, acidic, dry) and temperature conditions (hot fill, ambient, frozen)

YOUNGSUN provides FSC certification as standard. For specific food-contact compliance documentation, buyers should specify requirements when requesting a quotation.

Practical Buyer Checklist

Before placing an order for food-grade paper or board, confirm:

• Product type and application
• Required grammage
• PE coating: none, single-side, or double-side
• For greaseproof: KIT level requirement
• Sheet or reel size
• Food type the packaging will contact (fatty, aqueous, acidic, dry)
• Hot, ambient, or frozen service temperature
• Target market (USA, EU, China, other)
• Required compliance documentation
• Printing requirements (pre-converting or post-converting)
• Quantity
• Destination port

Conclusion

Food packaging paper and board are technical products where specification accuracy matters. Cupstock grammage must match cup size and contents. Greaseproof KIT rating must match the food's grease load. PE coating configuration must match the liquid barrier and sealing requirements. Compliance documentation must match the target market.

The most successful food packaging projects start with a clear specification shared between buyer and supplier. When both sides understand the application, the food type, the converting process, and the compliance requirements, sampling, pricing, and production proceed more smoothly.

FAQ

What is the difference between greaseproof paper and PE coated paper?

Greaseproof paper achieves barrier through dense fiber structure (mechanical treatment). PE coated paper achieves barrier through a polyethylene coating layer (extrusion lamination). Greaseproof is typically used for wraps and liners; PE coated paper is typically used for cups and containers requiring liquid barrier.

What KIT rating do I need for burger wrap?

KIT 6–8 is typically sufficient for burgers and sandwiches. Higher-fat products like fried chicken or cheese may require KIT 8+.

Can cupstock be used without PE coating?

Uncoated cupstock can be used for cold drinks with an aqueous or wax coating applied during converting, but PE coating is the industry standard for reliable liquid barrier and heat-sealing performance.

Is FSC certification available for food-grade papers?

Yes. YOUNGSUN food-grade paper and board products are available with FSC certification.

Related Products and Guides

• Cupstock Board — 160–330 gsm virgin-fibre cup paper
• Greaseproof Paper — KIT 6+ oil-resistant food wrap
• PE Coated Paper — moisture barrier & heat-seal packaging
• Silicone Coated Paper — non-stick release baking paper
• Kraft Paper — natural kraft for bags and wraps
• All Products & Categories