The IS 5807 Part 6 (1978) outlines a comprehensive testing approach for clear coatings applied to wooden furniture, focusing on their ability to resist mechanical damage. It integrates three distinct evaluations—impact, cross-cut adhesion, and scrape resistance—to determine the durability of finishes against typical mechanical wear. This standard is crucial for manufacturers, quality inspectors, and suppliers aiming to verify finish performance or ensure compliance with predefined durability benchmarks.
Overview
The IS 5807 Part 6 (1978) outlines a comprehensive testing approach for clear coatings applied to wooden furniture, focusing on their ability to resist mechanical damage. It integrates three distinct evaluations—impact, cross-cut adhesion, and scrape resistance—to determine the durability of finishes against typical mechanical wear. This standard is crucial for manufacturers, quality inspectors, and suppliers aiming to verify finish performance or ensure compliance with predefined durability benchmarks.
Audience
Contents
Structure
Details the precise dimensions and construction requirements for scraper blades, scrape heads, and associated accessories used in coating tests. Dimensions are specified in millimeters with a tolerance of ±0.1 mm unless indicated otherwise. Includes specifications for the scraper blade holder with features for blade projection and clamping, scrape head design with screw drive provisions, cutting blade slit arrangement, fitting template, magnifying inspection lens, and adjustable test table setup with reference bars. Notes emphasize the need for purchaser-seller agreements on specific conditions and observation of failure modes during testing.
Focuses on surface penetration force ratings for materials/components. Provides a table correlating penetration force values (in Newtons) to rating scores from 0 to 4. Clarifies that ratings are derived directly from measured penetration forces without formulae and highlights the importance of mutual agreements on interpretation between purchaser and seller.
Stipulates that purchaser and supplier must mutually agree on specific test conditions not detailed in the standard. Presents a table for assigning basic ratings based on force at surface penetration and explains that higher forces reflect superior surface resistance. Emphasizes the importance of this rating table in surface penetration resistance evaluation.
Describes apparatus requirements including calibrated instruments for measuring surface roughness and texture. Outlines systematic procedures for conducting multiple readings at designated surface locations and averaging results. Specifies conducting three component tests (impact, cross-cut, scrape) on test specimens, rating each individually, and calculating an overall rating typically by averaging. Details surface preparation to ensure representative and clean test conditions.
Covers general aspects of steel wire ropes (note: possibly misreferenced) including purchaser-seller agreements on construction, diameter, and breaking load. Provides approximate formulae for calculating breaking load based on nominal cross-sectional area and tensile strength. Highlights classification and acceptable tolerances. (This section may be contextually misplaced but retained for completeness.)
Describes the procedure where a standardized steel ball is dropped from a specific height onto the test surface to create an indentation. Damage surrounding the impact area is visually rated by at least five observers using a numerical scale without intermediate values. The final impact rating is determined by the majority's highest rating that is met or exceeded. Testing conditions include minimum two test locations on different wood grain orientations and controlled temperature.
Explains forming a lattice pattern on the finish by making two sets of 11 cuts each at right angles, spaced 2 mm apart and about 35 mm long, angled approximately 45° to the wood grain. After cutting, loose finish is removed with a soft brush. Ratings are assigned by five or more observers using integer values, with final rating determined by majority. Key parameters and test setup are specified to assess coating adhesion.
Outlines the test where a calibrated scraper blade is drawn across the wood grain at a constant speed, with gradually increasing force until surface penetration occurs, followed by penetration to the substrate. The forces at these two points are recorded. The surface penetration force forms the basis for a basic rating which is then adjusted by a modifying factor calculated using the additional force to penetrate the film. Observers independently rate the results to ensure unbiased assessment.
Details the calculation of the modifying factor as the ratio of difference between substrate and surface penetration forces to the surface penetration force, rounded to one decimal place and capped at 4. The modified rating equals the basic rating plus this factor. The standard requires reporting individual test ratings, the modified rating, overall assessment, and details of test conditions and surface preparation to ensure clarity and transparency.
Provides formulae and tables for assigning basic ratings based on force at surface penetration and calculating the modifying factor for the modified rating. Specifies reporting requirements including average impact, cross-cut, and scrape ratings along with force measurements and overall finish performance rating.
Specifies that reports must include average ratings for impact, cross-cut, and scrape tests, forces measured at surface and substrate penetration, and the final modified rating. Emphasizes rounding rules and limits for the modifying factor to maintain consistency. Also requires documentation of test conditions and observations for comprehensive evaluation.
Defines acceptance thresholds stating that finishes must have average impact and cross-cut ratings greater than 2, scrape rating at least 1, and an overall rating of 7 or more. Provides appearance-based rating descriptions for impact damage and reiterates the modified rating calculation method. Notes that final acceptance depends on mutual agreement between purchaser and supplier.
Frequently Asked
IS 5807 Part 6 (1978) employs three distinct mechanical tests to gauge the durability of clear finishes on wooden furniture against mechanical damage: 1. Scratch Resistance Test — assesses the finish's ability to withstand surface scratching under defined conditions. 2. Indentation Resistance Test — evaluates the capacity of the finish to resist permanent dents or deformations caused by a specified indenter and load. 3. Impact Resistance Test — measures the finish's toughness against sudden impact forces, typically using a falling weight or pendulum. Together, these tests provide a comprehensive mechanical damage resistance rating for wood finishes.
Calibration of the scraper blade in the scrape resistance test involves: 1. Mounting the scraper blade in its holder, which allows angle adjustments and locking. 2. Positioning the test panel on an adjustable table so that scraping occurs across the grain. 3. Using a reference blade, performing a scrape on a standard finished panel and adjusting table height to ensure the reference arm is horizontal, maintaining a constant blade angle. 4. Replacing the reference blade with the blade to be calibrated, then adjusting its angle until the measured scraping forces match those obtained with the reference blade. 5. Firmly clamping the blade holder to secure the calibrated angle. This process ensures consistent force measurements and reproducible test results.
The finish performance under IS 5807 Part 6 is evaluated using a composite rating system derived from three mechanical tests: impact, cross-cut adhesion, and scrape resistance. Each test area is visually inspected and rated on a scale from 0 to 4 based on observed damage severity, with no intermediate scores allowed. The final rating for each test is determined by the majority consensus of at least five observers. The sum of these individual ratings constitutes the overall rating. To be acceptable, a finish must exceed minimum thresholds in each test (typically impact and cross-cut ratings above 2, scrape rating at least 1) and achieve an overall score of 7 or more. This composite rating reflects the finish's ability to withstand typical mechanical stresses encountered during furniture use.
IS 5807 Part 6 prescribes the following environmental conditions to ensure consistent and reliable test results: Aging of the final coating must be conducted at a temperature not below 15°C with free air circulation for a minimum period of 28 days unless otherwise agreed. Testing procedures—impact, cross-cut, and scrape—should be performed at a controlled temperature of 27 ± 2°C with tests conducted at a minimum of two locations exhibiting different grain orientations. Inspection should occur under adequate lighting, employing magnifying lenses as needed, and panels should be rotated to achieve uniform viewing conditions.
IS 5807 Part 6 is one segment of a broader series of standards addressing test methods for clear finishes on wooden furniture. While Part 6 focuses specifically on assessing resistance to mechanical damage, other parts cover diverse performance aspects including resistance to dry heat (Part I), wet heat (Part II), marking by oils and fats (Part III), marking by liquids (Part IV), and low-angle glare (Part V). Together, these parts provide a comprehensive evaluation framework for the durability and performance of wooden furniture finishes under various environmental and usage conditions. Part 6 builds upon international standards like BS 3962 Part 6 (1975) to maintain global alignment.
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