Flame-retardant Kraft Paper Testing Service

Flame‑Retardant Kraft Paper Testing Service – Accredited Fire Performance, Mechanical Strength and Durability Evaluation for Global Markets

Our internationally accredited laboratory delivers a specialist flame‑retardant kraft paper testing service that provides manufacturers of fire‑resistant packaging, electrical insulation papers, building‑construction underlayments, automotive gasket materials, furniture backing and protective wrapping worldwide with the independent, traceable data they need to certify the ignitability, the surface flame spread, the heat release, the smoke production, the mechanical integrity and the long‑term durability of their treated and inherently fire‑safe kraft papers. Every test is performed under the rigorous framework of ISO/IEC 17025, and each report bearing the ILAC mark is unconditionally accepted by regulatory authorities, notified bodies and supply‑chain partners in all major economies. The flame‑retardant kraft paper testing service subjects the sheet or the converted product to a complete suite of reaction‑to‑fire, physical, chemical and environmental‑ageing evaluations, providing the legally robust, defensible data that underpin the CE marking, the UL component recognition, the compliance with the IMO FTP Code, the building‑code acceptance and the guarantee of the passive fire protection over the entire service life of the paper.

Product Samples We Regularly Subject to Flame‑Retardant Kraft Paper Testing

The oxygen‑bomb calorimeters, the cone‑calorimeter workstations, the vertical‑and‑horizontal flame‑test chambers, the smoke‑density analysers, the universal tensile‑test frames, the Elmendorf tear testers, the environmental‑ageing ovens and the chemical‑immersion baths in our facility accommodate a broad variety of flame‑retardant kraft papers and their converted products. The following categories represent the most frequently tested items:

Post‑impregnated and the coated flame‑retardant kraft papers – the natural kraft sheets that have been treated with the ammonium‑phosphate, the ammonium‑sulfate, the borate, the guanidine‑phosphate or the intumescent‑coating formulations to achieve the desired fire‑performance classification
Inherently fire‑retardant kraft papers – the papers that incorporate the flame‑retardant chemicals at the pulp‑stage or during the papermaking process, providing the permanent, the non‑leachable fire protection
Multi‑layer and the laminated flame‑retardant kraft constructions – the products that combine the treated kraft paper with the aluminium foil, the polymeric films or the fibreglass reinforcement for the enhanced barrier and the mechanical properties, used in the building‑envelope vapour‑retarder and the reflective‑insulation facings
Creped, embossed and the extensible flame‑retardant kraft papers – the high‑stretch, the conformable grades that are used for the masking, the wrapping and the furniture‑spring‑cover applications where the fire safety must be maintained during the forming and the flexing
Flame‑retardant kraft paper for the electrical insulation – the diamond‑pattern, the diamond‑dotted and the plain kraft papers that are impregnated with the electrical‑grade varnishes and the flame‑retardant resins, used in the transformer‑coil insulation, the motor‑slot liners and the cable‑wrap applications
Prototype, aged and the field‑retrieved flame‑retardant kraft paper specimens – the samples that have undergone the thermal‑cycling, the humidity‑soaking, the UV‑exposure or the prolonged service, submitted for the residual‑fire‑performance and the mechanical‑property assessment

Reaction‑to‑Fire and Surface Burning Characteristics – Flame‑Retardant Kraft Paper Testing According to ASTM E84, EN 13501‑1 and ISO 5660

Determination of the surface‑burning characteristics – the flame‑spread index and the smoke‑developed index – according to ASTM E84 (Standard Test Method for Surface Burning Characteristics of Building Materials) and the equivalent CAN/ULC‑S102: the flame‑retardant kraft paper is mounted on the ceiling of the Steiner‑tunnel apparatus, and the flame‑spread and the smoke‑density are measured over the 10‑minute test duration. The paper is classified as Class A (flame‑spread index 0–25), Class B (26–75) or Class C (76–200) according to the ASTM E84, providing the mandatory fire‑safety data for the interior‑finish and the building‑material acceptance in the North American and the Middle‑Eastern markets. This flame‑retardant kraft paper testing service is the primary classification test for the products that are installed in the occupied buildings.
Euroclass reaction‑to‑fire classification according to EN 13501‑1 (Fire classification of construction products and building elements) using the data from the EN 13823 Single Burning Item (SBI) test and the EN ISO 11925‑2 small‑flame ignitability test: the kraft paper is mounted on a calcium‑silicate or a gypsum‑board substrate in the SBI room‑corner test, and the fire‑growth‑rate index, the total heat release, the lateral flame spread and the smoke‑growth‑rate index are measured. The product is classified as A2‑s1,d0, B‑s1,d0, C‑s2,d1 or a lower class, as required by the national building regulation for the internal and the external wall‑linings of the European Union.
Measurement of the heat‑release rate, the effective heat of combustion and the mass‑loss rate by the cone‑calorimeter method according to ISO 5660‑1 (Reaction‑to‑fire tests – Heat release, smoke production and mass loss rate) and ASTM E1354: a specimen of the flame‑retardant kraft paper is exposed to a defined radiant‑heat flux of 35 kW/m² or 50 kW/m², and the ignition time, the peak heat‑release rate, the total heat released and the specific extinction area (the smoke parameter) are reported, providing the fundamental fire‑hazard data that the risk‑assessment engineer uses to model the contribution of the paper to a developing compartment fire.
Determination of the gross heat of combustion (the calorific value) by the oxygen‑bomb calorimeter method according to EN ISO 1716 (Reaction to fire tests for products – Determination of the gross heat of combustion): a small, representative sample of the dried kraft paper is combusted in a pressurised oxygen atmosphere, and the maximum heat that is released is measured. For a material to achieve the A1 or the A2 Euroclass classification, the gross heat of combustion must not exceed the specified limit, and this test provides the definitive pass‑or‑fail data for the non‑combustibility assessment.

Ignitability, Flame Spread and Small‑Flame Testing – Vertical and Horizontal Burn According to UL 94, IEC 60695 and EN ISO 11925‑2

Vertical‑burn and the horizontal‑burn testing according to UL 94 (Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, adapted for the paper‑based materials) and the IEC 60695‑11‑10 (Fire hazard testing – Test flames – 50 W horizontal and vertical flame test methods): the flame‑retardant kraft paper is subjected to a defined 50 W or 20 mm gas‑flame for a specified duration, and the after‑flame time, the after‑glow time, the dripping‑ignition of the cotton indicator and the extent of the char‑damage are recorded, providing the V‑0, the V‑1, the V‑2 or the HB flammability rating that is required for the electrical‑insulation, the appliance‑component and the automotive‑interior applications. This flame‑retardant kraft paper testing service is the standard material‑qualification test for the electronic and the electrical industries.
Small‑flame ignitability and the edge‑ignition testing according to EN ISO 11925‑2 (Reaction to fire tests – Ignitability of products subjected to direct impingement of flame): the surface and the edge of the kraft paper are exposed to a small propane‑gas flame for 15 seconds or 30 seconds, and the ignition, the flame‑spread to the 150 mm mark and the flaming‑droplet production are assessed, providing the supplementary ignitability data that are required for the Euroclass classification.
Glow‑wire ignitability and the glow‑wire flammability testing according to IEC 60695‑2‑11 (Glow‑wire flammability test method for end‑products) and the IEC 60695‑2‑13 (Glow‑wire ignitability test method for materials): the flame‑retardant kraft paper is pressed against a heated glow‑wire at the temperatures of 550 °C, 650 °C, 750 °C or 850 °C, and the ignition, the flame‑duration and the ignition of the tissue‑paper indicator are assessed, providing the critical safety data for the unattended‑appliance and the high‑temperature electrical‑insulation applications.
Limiting‑oxygen‑index measurement according to ISO 4589‑2 (Plastics – Determination of burning behaviour by oxygen index, adapted for the paper‑based materials): the minimum oxygen concentration in the oxygen‑nitrogen mixture that supports the flaming combustion of the kraft paper is determined, providing the comparative, intrinsic‑flammability data that the compounder uses to optimise the flame‑retardant chemical type and the dosage.

Mechanical Strength and Physical Properties – Flame‑Retardant Kraft Paper Testing According to TAPPI, ISO and ASTM Standards

Determination of the tensile strength, the elongation at break and the tensile‑energy‑absorption by the constant‑rate‑of‑elongation method according to TAPPI T 494 (Tensile properties of paper and paperboard) and ISO 1924‑2: a strip specimen of the flame‑retardant kraft paper is pulled in the machine direction and the cross direction, and the breaking force, the stretch at break and the tensile‑energy‑absorption are reported, providing the fundamental mechanical data that the converter uses to guarantee the runnability of the paper on the printing, the corrugating and the rewinding machines without the web‑breaks. This flame‑retardant kraft paper testing service verifies that the flame‑retardant chemical treatment has not excessively embrittled the cellulose fibres.
Elmendorf tear resistance according to TAPPI T 414 (Internal tearing resistance of paper) and ISO 1974: the mean tearing force in the millinewtons is reported, quantifying the resistance of the flame‑retardant kraft paper to the tear‑propagation from a nick or a perforation, which is critical for the die‑cut gaskets, the masking‑tape backings and the packaging applications.
Mullen burst strength and the puncture resistance according to TAPPI T 403 (Bursting strength of paper) and the internal procedures: the hydrostatic pressure that is required to rupture the paper, or the force that is required to drive a probe through the paper, is measured, providing the data that the designer uses to guarantee the resistance of the paper to the out‑of‑plane loading, the sharp‑object penetration and the handling damage.
Measurement of the basis weight, the caliper and the apparent density according to TAPPI T 410 (Grammage of paper and paperboard) and TAPPI T 411 (Thickness – caliper – of paper, paperboard and combined board): the mass per unit area in the grams per square metre, the single‑sheet thickness in the micrometres and the density are reported, providing the essential quality‑control parameters for every production batch.
Wet‑strength and the water‑absorption testing according to TAPPI T 456 (Wet tensile breaking strength of paper and paperboard) and the internal Cobb method (ISO 535): the retention of the tensile strength after the water saturation, and the mass of the water that is absorbed by the paper surface per unit area, are measured, providing the data that the specifier uses to select the correct flame‑retardant paper for the humid, the outdoor‑exposed and the condensation‑prone environments.

Smoke Production, Toxicity and Gas Analysis – Flame‑Retardant Kraft Paper Evaluation for the Enclosed and the Marine Applications

Determination of the specific optical density of the smoke and the smoke‑obscuration by the NBS smoke‑chamber method according to ASTM E662 (Standard Test Method for Specific Optical Density of Smoke Generated by Solid Materials) and the IMO FTP Code Part 2: the flame‑retardant kraft paper is exposed to a radiant‑heat source in the flaming and the non‑flaming modes, and the maximum smoke density Dm and the time to the critical obscuration are reported, providing the smoke‑production data that are mandatory for the certification of the materials that are installed in the marine vessels, the railway carriages and the public‑assembly spaces. This flame‑retardant kraft paper testing service is required for the compliance with the International Maritime Organization fire‑safety requirements.
Analysis of the fire‑effluent gases – the carbon monoxide, the carbon dioxide, the hydrogen cyanide, the hydrogen chloride, the sulfur dioxide and the other toxic species – by the Fourier‑transform infrared spectroscopy and the electrochemical‑sensor methods according to the EN 45545‑2 (Railway applications – Fire protection on railway vehicles – Part 2: Requirements for fire behaviour of materials and components) and the IMO FTP Code Part 2: the gases that are evolved during the cone‑calorimeter or the NBS smoke‑chamber test are sampled and analysed, and the concentration of each acute‑toxic species is reported, providing the data that the fire‑safety engineer uses to assess the tenability and the evacuation‑safety of the building, the train or the ship.
Corrosivity of the fire effluents according to the IEC 60754‑2 (Test on gases evolved during combustion of materials from cables – Part 2: Determination of acidity – by pH measurement and conductivity) and the internal procedures: the combustion gases are bubbled through the de‑ionised water, and the pH and the conductivity of the resulting solution are measured, providing the corrosivity data that are critical for the protection of the sensitive electronic equipment and the structural steel in the fire‑affected compartments.

Durability Under Environmental Stress – Flame‑Retardant Kraft Paper Testing for the Long‑Term Fire‑Performance Retention

Thermal‑ageing and the long‑term thermal stability according to ASTM D3045 (Standard Practice for Heat Aging of Plastics Without Load, adapted for the paper‑based materials) and the internal procedures: the flame‑retardant kraft paper is aged in a forced‑air oven at the elevated temperatures – typically 80 °C, 105 °C or 120 °C – for the extended periods, and the retained tensile strength, the tear resistance, the flame‑spread index and the visual degradation are measured, providing the data that the manufacturer uses to set the shelf‑life and the maximum continuous‑service temperature. This flame‑retardant kraft paper testing service verifies that the flame‑retardant chemicals do not migrate, volatilise or degrade over the time.
Resistance to the humidity and the water‑leaching of the flame‑retardant chemicals according to the internal validated protocol and the principles of the ASTM D3201 (Standard Test Method for Hygroscopic Properties of Fire‑Retardant Wood and Wood‑Based Products, adapted for the paper): the treated kraft paper is exposed to the high‑humidity environment or is immersed in the water, and the amount of the flame‑retardant salts that are leached out is measured by the conductivity or the ion‑chromatography, and the post‑leaching fire performance is re‑evaluated, ensuring that the paper retains its fire‑protective properties even after the accidental wetting or the condensation exposure.
Accelerated weathering and the UV‑radiation resistance according to ASTM G154 (Standard Practice for Operating Fluorescent Ultraviolet Lamp Apparatus for Exposure of Non‑Metallic Materials) and ISO 4892‑2: the flame‑retardant kraft paper is exposed to a cycle of the UV‑A or the UV‑B radiation, the heat and the condensation, and the colour‑change, the tensile‑strength retention and the fire‑performance are evaluated, predicting the outdoor‑storage and the exposed‑service life of the paper in the construction and the agricultural applications.
Resistance to the mould and the fungal growth according to ASTM G21 (Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi) and the ISO 846: the flame‑retardant kraft paper is inoculated with the spores of the Aspergillus niger, the Penicillium funiculosum and the other common fungi, and the extent of the mould‑coverage and the loss of the tensile strength are evaluated, providing the data that the specifier uses to approve the paper for the humid, the condensation‑prone and the tropical environments.

Report Acceptance and Global Regulatory Compliance

All measurements performed within our flame‑retardant kraft paper testing service are executed under the fully accredited scope of our ISO/IEC 17025 quality management system. Each test report that carries the ILAC mark is therefore automatically recognised by regulatory authorities, notified bodies, customs offices and supply‑chain partners in all major economies. For flame‑retardant‑paper mills, chemical‑treatment formulators, electrical‑insulation converters, building‑material distributors and automotive‑gasket suppliers anywhere in the world, the report constitutes legally robust, internationally accepted evidence that the ignitability, the flame‑spread, the heat‑release, the smoke‑production, the mechanical strength, the leaching resistance and the long‑term durability of the flame‑retardant kraft paper have been determined in accordance with the applicable ASTM, ISO, EN, UL, IMO and customer‑specified methods. The documentation can be directly used to support the CE marking under the Construction Products Regulation, the UL component recognition, the IMO MED certification, the issue of inspection certificates according to EN 10204 or equivalent national standards, and the resolution of commercial and technical disputes concerning the fire‑safety and the protective performance of any flame‑retardant kraft paper product.