Greaseproof Paper: Applications, Characteristics, and Maintenance

Introduction to Greaseproof Paper

Greaseproof paper, also known as parchment paper or vegetable parchment, is a specialized paper product engineered to resist oil and grease penetration. This unique property is achieved through a manufacturing process called parchmentizing, where the paper undergoes sulfuric acid treatment or intensive mechanical refining that modifies the cellulose fibers to create a dense, non-porous structure. The resulting material exhibits oil resistance of 85-95% according to TAPPI T559 standards, making it invaluable in numerous industrial and domestic applications.

Key Characteristics with Technical Data

1. Oil and Grease Resistance

The primary characteristic of greaseproof paper is its ability to resist oil penetration. Laboratory tests using the Kit test (TAPPI T559) demonstrate that high-quality greaseproof paper can withstand oil penetration for over 120 minutes at standard conditions (23°C, 50% RH), compared to just 2-5 minutes for regular paper. This resistance is quantified by the Kit rating system, with premium greaseproof papers achieving Kit 10-12 ratings.

2. Heat Resistance

Greaseproof paper exhibits exceptional thermal stability, withstanding temperatures up to 220°C (428°F) for short durations and continuous use at 180°C (356°F). Differential Scanning Calorimetry (DSC) analysis shows no significant thermal degradation below 230°C, making it suitable for baking applications. The paper's thermal conductivity ranges between 0.05-0.07 W/m·K, providing effective insulation against heat transfer.

3. Moisture Barrier Properties

While primarily designed for grease resistance, greaseproof paper also demonstrates moderate moisture barrier capabilities. Water vapor transmission rate (WVTR) tests at 38°C and 90% RH show values of 15-25 g/m²/24h, significantly lower than untreated paper (typically 300-500 g/m²/24h). This property is enhanced in silicone-coated varieties, which can achieve WVTR as low as 5 g/m²/24h.

4. Mechanical Strength

Tensile strength tests (ISO 1924-2) reveal that greaseproof paper maintains substantial durability despite its refined structure. Machine-direction tensile strength typically ranges from 40-70 kN/m, with elongation at break of 3-6%. The paper's density falls between 0.8-1.1 g/cm³, and its basis weight commonly varies from 30-100 g/m² depending on application requirements.

5. Chemical Inertness

Greaseproof paper demonstrates excellent chemical stability, with pH values typically between 6.5-7.5. It shows minimal reactivity with food constituents, maintaining <0.1% extractable substances when tested according to FDA 21 CFR 176.170. The paper's porosity, measured by Gurley densometer, exceeds 1000 seconds for 100 mL of air, confirming its dense structure.

Application Scenarios

Food Industry Applications

• Baking and Cooking: Used as non-stick liners for baking sheets, withstanding temperatures up to 220°C. Commercial bakeries report 15-20% reduction in cleaning time when using greaseproof liners.

• Fast Food Packaging: Wrapping for greasy foods like burgers and fried chicken, where it prevents 90-95% of grease transfer to outer packaging.

• Butter and Cheese Wrapping: Specialized grades with 40-50 µm thickness provide oxygen barriers of 10-15 cc/m²/day, extending dairy product shelf life.

Industrial Applications

• Adhesive Backing: Used as release liners for pressure-sensitive adhesives, with peel forces measuring 0.1-0.3 N/25mm.

• Pharmaceutical Interleaving: Between medical tablets, showing <0.01% particulate contamination in USP tests.

• Electronics Manufacturing: As temporary masking material during conformal coating, resisting solvents with ≥8 on the ASTM D5402 scale.

Specialty Applications

• Art Conservation: Acid-free varieties (pH 7.0-8.5) used for interleaving valuable prints and drawings.

• Floral Industry: As waterproof wrapping with water holdout values exceeding 300 seconds in Cobb60 tests.

• Candle Making: As wick stabilizers, demonstrating flame resistance up to 190°C without charring.

Maintenance and Care Guidelines

Storage Conditions

Optimal storage requires environments maintained at 20-25°C and 40-60% relative humidity. Under these conditions, the paper maintains its functional properties for 24-36 months. Storage in high humidity (>70% RH) can reduce grease resistance by 15-20% due to fiber swelling, while temperatures above 30°C may accelerate aging.

Handling Procedures

• Use clean, dry hands or lint-free gloves to prevent contamination (oil absorption increases by 30-40% with fingerprint contamination).

• For precision applications, cut with rotary trimmers rather than tearing to maintain edge integrity (torn edges show 50% higher grease penetration rates).

• When using in printers, select models with fuser temperatures below 180°C to prevent curling or brittleness.

Cleaning Methods

For reusable greaseproof paper (typically 120-150 g/m² grades):

• Wipe gently with 70% isopropyl alcohol solution, which evaporates completely in 15-20 seconds without residue.

• For baked-on residues, soak in 40-50°C water with mild detergent for 5-10 minutes, then pat dry.

• Never use abrasive cleaners, which increase surface porosity by 300-400% when measured by air permeability tests.

Performance Monitoring

Regular quality checks should include:

• Grease resistance testing (Kit test) every 6 months for stored inventory

• Thickness measurements (ISO 534) with tolerance of ±5% from specification

• Visual inspection for discoloration, which indicates oxidation when ΔE exceeds 3.0 in CIELab measurements