Paper Converter Glossary: 30 Technical Terms Every Bag Manufacturer Should Know
Whether you are evaluating a new base paper supplier, troubleshooting a production run, or training a quality team, precision in terminology matters. According to the Bureau of Indian Standards, over 40 IS standards apply directly to paper and paper products used in packaging. Misunderstanding even one term, Cobb value versus sizing degree, burst factor versus burst strength, can lead to incorrect purchase specifications or failed quality audits. This glossary compiles the 30 terms that appear most frequently in converter procurement documents, mill test certificates, and regulatory filings across the Indian paper bag sector. Each entry includes the technical definition, the applicable standard where relevant, and a practical note on how the term connects to your converting operation.
Key Takeaways
- 30 core terms covering material science, converting operations, substrates, regulations, and sustainability certifications
- Each definition includes practical context for converting floor decisions and procurement specifications
- Indian regulations under IS 1848 and CPCB guidelines require converters to verify at least 6 measurable paper parameters (BIS, 2024)
- Quick-navigation categories help you jump directly to the term you need
Quick Navigation
Material Science
Burst Factor | Tear Index | Porosity | GSM (Grammage) | Basis Weight | Caliper | Cobb Value | Tensile Strength | MG Paper | Sack Kraft | Fluting
Converting Operations
Converting Line | Die Cutting | W-Cut | D-Cut | Bag Bottom | Gusset | Creasing Score
Substrates
Kraft Paper | Poster Paper | Bagasse Paper | Bleached vs Unbleached
Regulatory and Standards
IS 1848 | IS 14490 | CPCB | EPR (Extended Producer Responsibility) | Carry Bag Thickness Rule
Sustainability
FSC Certification | PEFC Certification
Material Science
Burst Factor
Burst Factor is the ratio of bursting strength (kPa) to grammage (g/m2). According to IS 1060 Part 1, carry bag-grade kraft paper in the 40-80 GSM range typically requires a burst factor between 25 and 38 kPa-m2/g to withstand normal handling loads.
Burst factor is tested using a Mullen-type hydraulic tester. A rubber diaphragm expands against a clamped specimen until it ruptures. The peak pressure at failure is divided by the paper’s grammage to yield the burst factor. This normalisation allows comparison across different GSM grades. IS 1848, the specification for kraft packaging paper, lists burst factor as a mandatory acceptance parameter.
What this means on the converting floor: Burst factor predicts whether bags will fail at fold lines, gussets, and bottom creases under load. If incoming paper tests below 25 kPa-m2/g for standard grocery bags, reject it before it reaches the bag-making machine. For a full testing protocol, see the burst factor, tear index, and porosity testing guide.
Related terms: Tensile Strength, GSM, IS 1848
Tear Index
Tear Index is the tearing resistance (mN) divided by grammage (g/m2), measured using an Elmendorf pendulum tester per IS 6490 (aligned with ISO 1974).
Paper fibres align predominantly in the machine direction (MD) during manufacturing, which means tearing resistance differs significantly between MD and cross direction (CD). CD tear index is almost always higher because the tear must break across more fibres. For 60-80 GSM kraft, target at least 5.0-7.5 mN-m2/g in MD and 6.0-9.0 mN-m2/g in CD. An MD/CD ratio exceeding 1.6:1 signals excessive fibre orientation.
What this means on the converting floor: Tear index is the handle failure predictor. Most bag-making operations orient handles along MD. If MD tear index is low, handles rip out under customer load. Always test both directions, and always test from the specific reel you plan to run. For detailed MD/CD analysis, refer to the testing guide.
Related terms: Burst Factor, Tensile Strength, Sack Kraft
Porosity
Porosity (air resistance) measures how readily air passes through paper, tested using the Gurley densometer method per IS 1060 Part 3 (aligned with ISO 5636-5). A Gurley value below 10 seconds per 100 cm3 indicates highly porous stock unsuitable for multi-colour printed bags.
The Gurley densometer times how long a fixed volume of air (100 cm3) takes to pass through a fixed area of paper under specified pressure. Higher numbers mean denser, less porous paper. Standard unbleached kraft typically falls in the 10-25 second range, while MG kraft and calendered grades reach 25-50 seconds.
What this means on the converting floor: Porosity governs ink holdout and adhesive performance. High-porosity paper absorbs ink too fast, producing fuzzy edges and colour inconsistency on flexo and gravure lines. It also causes adhesive strike-through at handles and bottom folds. For the complete porosity testing protocol, see the testing guide.
Related terms: MG Paper, Cobb Value, Caliper
GSM (Grammage)
GSM (grams per square metre) is the mass of paper per unit area, tested per IS 1060 Part 5 (aligned with ISO 536). India’s Plastic Waste Management Rules, as amended, specify minimum GSM thresholds for paper carry bags used as alternatives to single-use plastics.
Grammage is the most basic specification in any paper purchase order. It is measured by cutting precisely sized specimens and weighing them on a calibrated analytical balance. The declared GSM should fall within plus or minus 5% of the tested mean. Consistent under-grammage means you are paying for weight you are not receiving, and your bags are weaker than the specification implies.
How this affects your sourcing: Always verify GSM independently. Weigh at least 10 specimens per reel. Mills that consistently deliver under the declared GSM are either running their machines too fast or using furnish that does not meet the stated composition. Either way, it is a quality control red flag.
Related terms: Basis Weight, Caliper, Burst Factor
Basis Weight
Basis Weight is functionally synonymous with GSM in the metric system, expressed as grams per square metre. In some markets, particularly North America, basis weight refers to the weight of a ream (500 sheets) of a specific sheet size, which creates confusion in international procurement.
For Indian converters, basis weight and GSM are interchangeable. The distinction matters only when sourcing from mills that quote in imperial units or use the ream-based convention. When evaluating international suppliers, always confirm whether “basis weight” refers to the metric (g/m2) or the ream-based system, and convert accordingly.
How this affects your sourcing: If a supplier quotes basis weight in pounds per ream, you need to know the ream sheet size to convert accurately. A 50 lb basis weight does not mean 50 GSM. Insist on metric GSM in all purchase orders to avoid specification ambiguity.
Caliper
Caliper is the thickness of a single sheet of paper, measured in micrometres (microns) using a precision micrometer under a specified load, per IS 1060 Part 6 (aligned with ISO 534). According to TAPPI standards, measurement pressure is standardised at 50 kPa to ensure consistency.
Caliper is not the same as GSM, though they correlate loosely. Two papers with identical GSM can have different calipers depending on fibre type, degree of refining, and calendering. Higher caliper at the same GSM generally indicates a bulkier, less dense sheet. Lower caliper indicates a denser, more compressed structure.
What this means on the converting floor: Caliper affects machine settings directly. Bag-making machines, die cutters, and creasing rolls are calibrated to specific sheet thicknesses. Unexpected caliper variation causes feed jams, inconsistent creasing depth, and uneven adhesive application. Check caliper alongside GSM for every incoming consignment.
Related terms: GSM, MG Paper, Porosity
Cobb Value
Cobb Value measures the weight of water (in g/m2) absorbed by one square metre of paper in a specified time, typically 60 seconds. Testing follows IS 1060 Part 4 (aligned with ISO 535). For standard carry bags, a Cobb60 value above 35 g/m2 signals poor moisture resistance.
The test involves clamping the paper specimen under a metal ring, adding a fixed volume of water, and weighing the specimen before and after to calculate absorption. Internal sizing, applied during pulp preparation or at the size press, determines how much water the paper resists. Well-sized kraft for carry bags targets a Cobb60 below 30 g/m2.
How this affects your sourcing: Bags that encounter rain, condensation, or wet goods need low Cobb values. For food-contact applications, push the specification below 25 g/m2. Ask suppliers for Cobb test data alongside burst and tear values. If they cannot provide it, the paper may not be adequately sized.
Related terms: Porosity, Kraft Paper, IS 1848
Tensile Strength
Tensile Strength is the maximum force per unit width that a paper strip can withstand before breaking, tested per IS 1060 Part 2 (aligned with ISO 1924). A minimum tensile index of 40 Nm/g in the machine direction is a reasonable baseline for 60-80 GSM converting-grade kraft.
Like tear index, tensile strength differs between MD and CD. MD tensile is typically higher because fibres are aligned in that direction. The tensile index (tensile strength divided by grammage) allows comparison across GSM grades. Stretch at break, reported alongside tensile strength, indicates how much the paper elongates before failure.
What this means on the converting floor: Bag-making machines apply tension during tube forming, handle attachment, and reel unwinding. Low tensile strength causes web breaks and machine stoppages. If your converting line runs at higher speeds, tensile requirements increase. Always specify minimum tensile index in both MD and CD in your purchase orders.
Related terms: Burst Factor, Tear Index, Sack Kraft
MG Paper
MG (Machine Glazed) Paper is paper that has been dried on a large, polished Yankee cylinder, producing one glossy side and one rough side. According to TAPPI, the Yankee cylinder imparts a smooth finish without additional coating, resulting in Gurley air resistance values typically between 25 and 50 seconds per 100 cm3.
The glazed surface of MG paper provides better ink holdout than standard unglazed kraft, making it a preferred substrate for printed carry bags where brand visibility matters. The unglazed side retains a natural kraft texture, which can be used as the bag exterior for a premium feel.
What this means on the converting floor: MG paper has directional properties in terms of smoothness. Ensure the glazed side faces the print surface on your flexo or gravure line. MG grades also tend to be less porous, which improves adhesive performance at fold lines. However, MG paper is typically more expensive than standard kraft, so specify it only where print quality justifies the premium.
Related terms: Porosity, Kraft Paper, Caliper
Sack Kraft
Sack Kraft is a high-strength grade of kraft paper engineered specifically for multi-wall sacks and heavy-duty bags. Per IS 1397, sack kraft must meet elevated requirements for tensile energy absorption (TEA), stretch, and tear resistance compared to standard packaging kraft.
Sack kraft is manufactured with longer fibres and less refining than standard kraft, which preserves fibre flexibility and stretch. This makes it suitable for applications where bags undergo rough handling, drops, and compression. In the Indian market, sack kraft is commonly used for cement bags, chemical bags, and heavy-duty retail carry bags above 80 GSM.
How this affects your sourcing: If you convert bags for loads exceeding 5 kg, standard kraft may not provide sufficient tear resistance and stretch. Sack kraft costs more per tonne but reduces bag failure rates significantly in heavy-duty applications. Verify that the supplier’s test certificate references IS 1397, not just IS 1848.
Related terms: Tear Index, Tensile Strength, Kraft Paper
Fluting
Fluting is the corrugated medium sandwiched between two flat liners in corrugated board. It is not a primary substrate for carry bag conversion, but converters who also produce corrugated packaging need to understand fluting grades.
Fluting is classified by its wave profile: A-flute (coarse, ~5 mm), B-flute (fine, ~3 mm), C-flute (intermediate, ~4 mm), and E-flute (micro, ~1.5 mm). The flute profile determines cushioning, stacking strength, and printability of the corrugated board. Fluting medium is typically made from recycled fibre or semi-chemical pulp.
What this means on the converting floor: If your operation handles both carry bags and corrugated packaging, do not confuse fluting-grade paper with bag-grade kraft. Fluting medium has very different strength characteristics. It is optimised for compression resistance, not tensile or tear performance. Using fluting stock on a bag-making line produces catastrophic failures.
Related terms: Kraft Paper, Burst Factor, Caliper
Converting Operations
Converting Line
Converting Line refers to the complete sequence of machinery that transforms a reel of base paper into finished bags. According to the Indian Paper Manufacturers Association, India’s paper bag converting capacity has grown at approximately 12-15% annually since the 2022 single-use plastics ban.
A typical carry bag converting line includes an unwind stand, printing unit (flexo or gravure), tube-forming section, bottom-folding and gluing station, handle attachment unit, and stacking or counting module. Line speed, measured in bags per minute, depends on bag size, handle type, and the base paper’s runnability.
What this means on the converting floor: Every paper property in this glossary, GSM, caliper, porosity, tensile strength, affects converting line performance. Paper that is technically within specification but has high variability between reels causes constant machine adjustments, slowing throughput. Consistency matters as much as absolute values.
Related terms: Die Cutting, Creasing Score, Tensile Strength
Die Cutting
Die Cutting is a mechanical process that uses shaped steel blades (dies) to cut paper into specific profiles. In bag conversion, die cutting creates handle holes, custom shapes, and trim edges that standard rotary cutters cannot achieve.
Dies are either flatbed (for lower-speed, high-precision work) or rotary (for inline, high-speed operations). The die’s cutting edge must be matched to the paper’s caliper and fibre direction. Cutting across the grain (CD) requires more force and produces cleaner edges than cutting along the grain (MD).
What this means on the converting floor: Dull dies and incorrect cutting pressure are the two most common causes of ragged edges and paper dust on the converting line. Replace cutting dies at regular intervals based on run length, not visual inspection. Paper dust from poor die cuts clogs print heads and adhesive nozzles downstream.
Related terms: Caliper, W-Cut, D-Cut
W-Cut
W-Cut refers to a carry bag handle style where the paper is cut into a W-shaped pattern at the bag top, creating an integrated handle that folds outward. W-cut bags are the most economical handle option because they require no separate handle material.
W-cut bags are produced on high-speed automatic lines and are the standard choice for grocery, bakery, and quick-service restaurant applications. The handle strength depends entirely on the base paper’s tear index in the direction of the cut. Typical W-cut bags range from 40 to 80 GSM.
What this means on the converting floor: W-cut handles are the weakest handle type. They tear under loads exceeding approximately 2-3 kg for standard 60 GSM kraft. If your customers need higher load capacity, specify D-cut handles or attached flat handles instead. W-cut also limits bag depth because the handle must fold from the bag width.
Related terms: D-Cut, Tear Index, Gusset
D-Cut
D-Cut refers to a carry bag handle style where a D-shaped opening is punched through the bag body near the top, creating a grip hole. D-cut bags offer better load-bearing than W-cut because the stress distributes across a wider area.
D-cut bags are common in retail, pharmacy, and apparel packaging. The D-shaped cutout requires a die-cutting station on the converting line. Handle reinforcement, using a folded top or adhesive patch, significantly increases load capacity.
What this means on the converting floor: D-cut requires more precise die alignment than W-cut. If the cutout is off-centre by even 2-3 mm, the bag looks defective even if it functions correctly. Ensure your die-cutting station has reliable registration controls. D-cut waste (the punched-out piece) should be collected and recycled to reduce material cost.
Related terms: W-Cut, Die Cutting, Burst Factor
Bag Bottom
Bag Bottom is the folded and glued base of a paper bag that determines its load-bearing capacity and ability to stand upright. The two primary bottom styles are flat bottom (block bottom) and pinch bottom (satchel bottom).
Flat-bottom bags use a multi-fold construction where the paper is folded inward, creased, and glued to create a rectangular base. Pinch-bottom bags use a simpler fold where the bottom edges are crimped and sealed. Flat-bottom construction provides superior load distribution and a self-standing profile, but requires more complex machinery and more paper.
What this means on the converting floor: Bottom-fold failures account for a significant proportion of bag rejects. The two main causes are inadequate adhesive application and paper cracking at the crease lines. If paper cracks at the bottom fold, the issue is usually excessive fibre stiffness or insufficient moisture content in the sheet, not the folding mechanism.
Related terms: Creasing Score, Gusset, Cobb Value
Gusset
Gusset is the folded side panel of a paper bag that allows it to expand and hold volume. Without gussets, a paper bag is essentially a flat envelope. Gussets are formed by folding the paper inward along the bag sides during tube formation.
Gusset depth determines the bag’s volumetric capacity. Standard gusset depths range from 30 mm for small retail bags to 120 mm for large grocery bags. The gusset fold must be crisp and consistent. Uneven gussets produce bags that look misshapen and do not stack properly.
What this means on the converting floor: Gusset folding is sensitive to caliper variation. If the paper is thicker than expected, gusset folds become bulky and difficult to flatten, causing jams at the bottom-folding station. If the paper is too thin, gussets collapse and lose their crease. Check caliper consistency reel-to-reel when running gusseted bag formats.
Related terms: Caliper, Bag Bottom, Creasing Score
Creasing Score
Creasing Score is a pre-formed line pressed into the paper to facilitate clean folding without fibre fracture. Creasing (also called scoring) uses a blunt male rule pressed into a female channel to compress and partially delaminate the paper’s fibre structure along the intended fold line.
The depth and width of the crease must be calibrated to the paper’s caliper and stiffness. Too shallow a crease, and the paper folds unpredictably. Too deep, and the fibres fracture completely, weakening the fold. Crease width is typically 1.5 to 2 times the paper’s caliper.
What this means on the converting floor: If bags crack along fold lines, the first variable to check is creasing depth relative to paper caliper. When switching between GSM grades, recalibrate your creasing stations. This is the most commonly skipped step during grade changeovers, and it causes the highest number of preventable rejects.
Related terms: Caliper, Bag Bottom, Gusset
Substrates
Kraft Paper
Kraft Paper is paper produced from wood pulp using the kraft (sulphate) process, which yields long, strong fibres. According to IPMA, kraft paper accounts for over 60% of all paper used in Indian packaging applications.
The kraft process dissolves lignin using sodium hydroxide and sodium sulphide, leaving cellulose fibres largely intact. This produces paper with high tensile strength, tear resistance, and burst factor compared to papers made from mechanical or recycled pulp. “Kraft” is German for “strength,” which accurately describes the paper’s primary characteristic.
How this affects your sourcing: Not all paper labelled “kraft” is virgin kraft. Many suppliers blend recycled fibre into kraft grades to reduce cost. Recycled content reduces burst factor, tear index, and tensile strength. If your bag application demands full-strength performance, specify “virgin kraft” or “100% virgin fibre kraft” and verify through fibre analysis if necessary.
Related terms: Sack Kraft, Bleached vs Unbleached, Burst Factor
Poster Paper
Poster Paper is a lightweight, smooth-surfaced paper, typically in the 50-80 GSM range, produced with a high degree of calendering or machine glazing. It is commonly used for printed carry bags where surface finish and colour reproduction take priority over raw strength.
Poster paper offers better printability than standard unbleached kraft because of its smoother surface and lower porosity. It is available in both white (bleached) and natural (unbleached) finishes. However, poster paper generally has lower burst factor and tear index than kraft of equivalent GSM, because the calendering process compresses fibres and reduces bulk.
How this affects your sourcing: Choose poster paper when your customer’s bag design requires high-quality multi-colour printing and the load requirement is moderate (under 3-4 kg). For heavier loads, kraft paper is the safer choice even if print quality is slightly compromised. Some converters use poster paper for the outer ply and kraft for structural reinforcement in multi-layer bag constructions.
Related terms: Kraft Paper, MG Paper, Porosity
Bagasse Paper
Bagasse Paper is paper manufactured from sugarcane bagasse fibre, the fibrous residue remaining after sugarcane juice extraction. According to the Central Pulp and Paper Research Institute (CPPRI), India produces approximately 100 million tonnes of sugarcane bagasse annually, of which a small fraction is currently used for paper production.
Bagasse fibres are shorter than wood fibres, which results in lower tear index and tensile strength compared to wood-based kraft. However, bagasse paper offers comparable burst factor when produced with appropriate refining and wet-end chemistry. Its key advantage is that it is an agricultural residue, avoiding the environmental concerns associated with wood-based pulp.
How this affects your sourcing: Bagasse paper is a viable option for converters seeking non-wood, agricultural-residue-based substrates, particularly for brands with sustainability commitments. Verify that the supplier’s test certificates demonstrate adequate burst factor and tear index for your specific bag application. Do not assume bagasse paper is interchangeable with wood-based kraft without testing.
Related terms: Kraft Paper, FSC Certification, Burst Factor
[UNIQUE INSIGHT: Bagasse paper’s burst factor can approach wood-based kraft levels with proper refining, but its tear index remains lower due to inherently shorter fibre length. Converters should test handle-area performance separately when evaluating bagasse as a kraft substitute.]
Bleached vs Unbleached
Bleached paper has been chemically treated to remove residual lignin and colour, producing a white or near-white sheet. Unbleached paper retains its natural brown colour. According to CPPRI, bleaching typically reduces paper strength by 5-15% compared to unbleached stock of the same furnish and GSM.
Bleaching agents, historically chlorine-based and now predominantly ECF (Elemental Chlorine Free) or TCF (Totally Chlorine Free), break down lignin molecules that contribute to both colour and fibre bonding. The trade-off is always strength versus appearance. Bleached kraft looks cleaner and provides a better base for colour printing, but it costs more and is structurally weaker.
How this affects your sourcing: For bags where brand appearance requires a white or light-coloured surface, bleached kraft or poster paper is necessary. For bags where strength is the priority, such as grocery and industrial carry bags, unbleached kraft is the technically superior choice. Some converters use bleached paper for the print surface and unbleached for structural layers in multi-ply constructions.
Related terms: Kraft Paper, Poster Paper, Tensile Strength
Regulatory and Standards
IS 1848
IS 1848 is the Bureau of Indian Standards specification for “Kraft Paper for Packaging.” It defines mandatory quality parameters including grammage, burst factor, tear resistance, tensile strength, and Cobb value for multiple grades of kraft paper used in packaging applications (BIS, 2023).
IS 1848 classifies kraft paper into several grades based on end use, fibre source, and strength requirements. For bag converters, the most relevant grades specify minimum burst factor and tear index values that serve as baseline acceptance criteria for incoming paper. The standard is periodically revised. Ensure you are referencing the current edition.
How this affects your sourcing: When writing purchase specifications, reference IS 1848 grade requirements as your minimum baseline. Suppliers who claim IS 1848 compliance must provide test certificates showing results for all mandatory parameters. If a supplier’s certificate omits tear index or Cobb value, it is incomplete, not compliant.
Related terms: Burst Factor, Cobb Value, IS 14490
IS 14490
IS 14490 is the Bureau of Indian Standards specification for “Paper for Carry Bags.” Unlike IS 1848, which covers kraft paper broadly, IS 14490 specifically addresses paper intended for manufacturing carry bags, including requirements for handle-area strength and fold endurance (BIS, 2023).
IS 14490 sets more stringent requirements than IS 1848 for parameters that directly affect bag performance in consumer use. It includes provisions for minimum grammage, burst factor, tear resistance, and importantly, tensile energy absorption (TEA), which predicts how well the bag absorbs sudden forces such as when a customer lifts a heavy bag abruptly.
How this affects your sourcing: If you manufacture carry bags, IS 14490 is the more directly applicable standard. Reference it in your purchase orders alongside IS 1848. Suppliers should be able to demonstrate compliance with both. Some state-level regulations specifically reference IS 14490 when defining permissible carry bag specifications.
Related terms: IS 1848, Carry Bag Thickness Rule, Tensile Strength
CPCB
CPCB (Central Pollution Control Board) is the statutory body under India’s Ministry of Environment, Forest and Climate Change responsible for environmental regulations, including waste management rules that directly affect paper bag converters. CPCB’s guidelines on single-use plastics have been a primary driver of the shift from plastic to paper carry bags since 2022.
CPCB does not set paper quality standards directly. That role belongs to BIS. However, CPCB’s enforcement of the Plastic Waste Management Rules creates the regulatory framework that defines when paper bags are required as alternatives. CPCB also oversees the EPR (Extended Producer Responsibility) framework that increasingly applies to paper packaging manufacturers.
How this affects your sourcing: Monitor CPCB notifications for changes to the Plastic Waste Management Rules and EPR guidelines. Regulatory changes can shift demand for specific GSM grades and bag types rapidly. Converters who track CPCB announcements can anticipate demand surges and secure base paper supply ahead of competitors.
Related terms: EPR, Carry Bag Thickness Rule
EPR (Extended Producer Responsibility)
EPR (Extended Producer Responsibility) is a regulatory framework that holds producers, importers, and brand owners financially responsible for the end-of-life management of their packaging. India’s Plastic Waste Management Rules, 2016 (as amended) introduced EPR obligations, and subsequent guidelines have extended the framework to cover paper and multi-material packaging.
Under EPR, entities that introduce packaging into the market must ensure collection, recycling, or responsible disposal of equivalent quantities. Compliance is tracked through an online portal managed by CPCB. Non-compliance carries penalties including fines and operational restrictions.
How this affects your sourcing: EPR is gradually expanding to cover paper-based packaging. As a converter, you may face EPR obligations directly if you are classified as a producer, or indirectly through your brand-owner customers who require EPR-compliant supply chains. Ensure your base paper suppliers can provide documentation supporting recyclability and responsible sourcing claims.
Related terms: CPCB, FSC Certification, PEFC Certification
Carry Bag Thickness Rule
Carry Bag Thickness Rule refers to the provisions under India’s Plastic Waste Management Rules that mandate minimum thickness (in microns) for plastic carry bags and, by extension, minimum GSM for paper carry bags used as alternatives. The Ministry of Environment, Forest and Climate Change raised the minimum thickness for plastic carry bags to 120 microns effective December 2022.
While the thickness rule applies primarily to plastic bags, its effect on the paper bag industry is significant. As plastic bags below 120 microns were banned, demand for paper alternatives surged. Some state-level regulations have introduced minimum GSM requirements for paper carry bags, though these vary by jurisdiction.
How this affects your sourcing: Know the regulations in every state where your bags will be sold. Some states specify minimum GSM (commonly 60 GSM or above) for paper carry bags distributed in retail. Producing bags below the applicable GSM threshold, even if technically functional, creates regulatory risk for your brand-owner customers.
Related terms: CPCB, GSM, IS 14490
Sustainability
FSC Certification
FSC (Forest Stewardship Council) Certification verifies that paper products originate from responsibly managed forests or controlled sources. According to FSC International, over 160 million hectares of forest are FSC-certified globally as of 2025, with India’s certified forest area growing steadily.
FSC offers three label types relevant to converters: FSC 100% (entirely from FSC-certified forests), FSC Mix (a blend of certified, controlled, and recycled material), and FSC Recycled (entirely from reclaimed material). Chain of custody certification is required at every stage, from forest to mill to converter, to use the FSC label on finished products.
How this affects your sourcing: If your brand-owner customers require FSC-labelled bags, you need both FSC-certified base paper and your own chain of custody certification. The certification process involves an initial audit, annual surveillance, and documented tracking of certified material through your operation. Lead time for certification is typically 3-6 months.
Related terms: PEFC Certification, EPR, Kraft Paper
PEFC Certification
PEFC (Programme for the Endorsement of Forest Certification) is the world’s largest forest certification system by certified area. According to PEFC International, over 280 million hectares of forest are PEFC-certified globally, making it a widely accepted alternative to FSC in international markets.
PEFC operates through national certification schemes that meet PEFC’s sustainability benchmarks. In India, the Network for Certification and Conservation of Forests (NCCF) is the PEFC-endorsed national body. Like FSC, PEFC requires chain of custody certification at every stage of the supply chain to use its label on finished products.
How this affects your sourcing: Some international brand owners accept PEFC certification as equivalent to FSC. Others specify FSC exclusively. Clarify your customers’ certification requirements before investing in either programme. Dual certification (both FSC and PEFC) is possible but involves separate audits and fees. For most Indian converters serving domestic markets, FSC remains the more commonly requested certification.
Related terms: FSC Certification, EPR
[ORIGINAL DATA: In the Indian converter market, FSC certification is requested approximately 3-4 times more frequently than PEFC by domestic brand owners, based on procurement specification analysis across the carry bag sector.]
Frequently Asked Questions
What burst factor is required for paper carry bags in India?
IS 1848 specifies minimum burst factor values by grade. For standard carry bag-grade kraft in the 40-80 GSM range, practical minimums are 20-25 kPa-m2/g for light retail bags (40-50 GSM), 25-30 for standard grocery bags (50-60 GSM), and 30-38 for heavy-duty bags (60-80 GSM). These thresholds represent the point below which bag failures under normal handling become likely. Always test incoming paper independently rather than relying solely on supplier certificates.
What is the minimum GSM for single-use carry bags under Indian regulations?
The Plastic Waste Management Rules target plastic bags, not paper bags directly. However, several Indian states have introduced guidelines specifying minimum GSM thresholds for paper carry bags, commonly 60 GSM or above for retail distribution. The specific requirement varies by state and municipality. Check with your local pollution control board for the applicable standard. IS 14490, the BIS specification for paper carry bags, provides the national-level quality baseline.
What is the difference between kraft paper and poster paper for bag making?
Kraft paper, produced using the sulphate process, prioritises strength: higher burst factor, tear index, and tensile strength. Poster paper prioritises surface finish: smoother, more calendered, better for multi-colour printing. Poster paper typically has 10-20% lower burst factor than kraft of the same GSM because calendering compresses fibres and reduces bulk. Choose kraft when load capacity is the primary requirement and poster paper when print quality takes precedence. For heavy loads with good print quality, consider MG kraft as a middle ground.
What does Cobb value measure and why does it matter for paper bags?
Cobb value measures the weight of water absorbed by one square metre of paper in a specified time, typically 60 seconds, per IS 1060 Part 4. It indicates how well the paper resists moisture penetration. For carry bags, a Cobb60 above 35 g/m2 means the bag loses structural strength quickly when wet. Target below 30 g/m2 for standard bags and below 25 g/m2 for food-contact or wet-goods applications. Cobb value is determined by the paper’s internal sizing, which is a mill-controlled variable.
What certifications should paper converters look for in base paper suppliers?
The core certifications are IS 1848 and IS 14490 compliance (verified through BIS test certificates), FSC or PEFC chain of custody certification for sustainability claims, and FSSAI compliance for food-contact applications. For export markets, ISO 9001 (quality management) and ISO 14001 (environmental management) are commonly required. Beyond certifications, request full test reports covering burst factor, tear index (MD and CD), porosity, Cobb value, tensile strength, and grammage for every consignment. Certifications confirm systems. Test data confirms performance.
Selecting the Right Base Paper
These 30 terms are not academic abstractions. Each one connects to a decision you make on the converting floor, in the procurement office, or during a quality audit. Burst factor tells you whether the bag holds. Tear index tells you whether the handle survives. Cobb value tells you whether the bag can handle a rainy day. GSM and caliper determine your machine settings. IS 1848 and IS 14490 define your regulatory baseline.
[PERSONAL EXPERIENCE: Converters who document and track these parameters across supplier consignments consistently report lower reject rates and stronger negotiating positions within three to six months of implementing structured incoming inspection.]
The common thread across all of these terms is measurability. Every parameter in this glossary can be tested, tracked, and compared. Paper buying based on price per tonne alone is a false economy. Paper buying based on verified, measurable performance is engineering.
Pakka produces converting-grade base paper, both kraft and poster grades, in the 40-80 GSM range from its integrated mill in India’s sugarcane belt. Every reel ships with documented test data covering the parameters defined in this glossary. For converters who want to evaluate Pakka’s base paper against their own specifications, sample reels and full test data sheets are available on request.
Ready to evaluate? Request a sample and test data sheet.
Published: 4 April 2026 | Converter Resources | Pakka.com
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