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24 Ways To Test Plywood Quality as per Bureau of Indian Standards (BIS: 1983) that are valid even today
Author
Ajit Phatak
Chief Chemist and Head - Quality Assurance
22 Years Plywood Manufacturing experience as manufaturing and quality assurance professional
Updated:
FlaerPly Pressure Test is one of the most intuitive and fastest way to test Plywood at your own place before making the purchase. This Pressure Test can be done in 15 min, does not need any speciality equipment, nor does it need any prior expertise. This is the new favourite way to test for new age interior designers as it saves them from shopkeeper fraud and fakes in just 15 minutes.
Bureau of Indian Standards (BIS) has been publishing the official standards on manufacturing and testing timber, wood, engineered wood with the primary aim of ensuring standards across manufacturers and protecting consumer interest by making non-adherence to standards a punishable offence.
How to Check Plywood Quality?
BIS has defined IS 701 and IS 303 as the primary standards of manufacturing for plywood. Additional standards of manufacturing are included for structural grade and fire grade plywood. Irrespective of all the manufacturing standards, BIS has defined a list of common tests that have to be used for plywood certification.
24 Methods of Checking Plywood Quality
FlaerPly has collected and simplified all the BIS tests as a summary for non-technical readers, including pass/fail criteria wherever applicable. We have also included any other Indian Standards (IS) as published by BIS, referenced within each test method.
| # | Test Name | Objective | How It's Done | Success Criteria | Reference to Related BIS Standard(s) |
|---|---|---|---|---|---|
| 1 | Density & Moisture Content | Check how heavy/dense the plywood is and how much water it contains | Weigh the sample, dry it in an oven at 103±2°C until weight stops changing, weigh again | No pass/fail – values are just calculated and reported | None referenced |
| 2 | Resistance to Dry Heat | Check if plywood layers separate when exposed to dry heat (storage conditions) | Dry sample in oven at 103±2°C for 3 hrs (longer for thicker boards), cool, then try to peel layers apart | Fail if: layers separate by more than 6.5mm deep and 50mm long, OR layers come apart completely at the glue, OR blisters appear on surface | None referenced |
| 3 | Fire Resistance – Flammability | Check how fire-resistant treatment performs when one piece catches fire near another | Two vertical pieces with a gas flame; time how long it takes for fire to spread from one piece to the other | No fixed pass/fail – time taken is recorded and compared based on intended use. (Note: "ignited" means burns continuously for 50+ seconds) | None referenced |
| 4 | Fire Resistance – Flame Penetration | Check how long it takes fire to burn through the plywood | Sample rotated above a blowpipe flame; time taken for flame to go through the thickness is recorded | No fixed pass/fail – time recorded and judged based on use | None referenced |
| 5 | Fire Resistance – Rate of Burning | Check how fast the plywood burns once on fire | Sample suspended in a tube, set on fire, time taken to lose 30% to 70% of its weight is recorded | No fixed pass/fail – time recorded and judged based on use | None referenced |
| 6 | Glue Shear Strength | Check how strongly the glue holds the layers together when pulled apart | Cut sample with notches between layers, pull apart in a machine at a steady rate (1300±500 N/min) until it breaks | No single pass/fail number here – result (breaking force + % wood failure) is compared against the requirement for that specific plywood grade | None referenced (results compared to relevant plywood specification, not specified by number) |
| 7 | Adhesion of Plies (Knife Test) | Check glue bond quality between layers using a knife | A sharp knife is worked along the glue line and the layer is pried up; quality is judged by how much wood fibre remains stuck and how hard it is to separate | Rated as "Excellent", "Minimum Pass", or "Poor" based on appearance (Excellent = very hard to find/separate glue line; Poor = layers peel off easily with little wood sticking) | None referenced |
| 8 | Water Resistance | Check if glue bond survives soaking/boiling in water | Samples soaked in boiling water (72 hrs for BWP grade, 8 hrs for BWR grade) or warm water at 60±2°C for 3 hrs (for MR grade), then tested for glue shear strength (Part 4) and/or ply adhesion (Part 5) while still wet | Must meet the same shear strength/adhesion requirements as specified for that plywood's grade and use; also checked visually for delamination/blisters | IS 1734 (Part 4)-1983 – Glue shear strength; IS 1734 (Part 5)-1983 – Adhesion of plies |
| 9 | Mycological Test (Fungus Resistance) | Check if the glue can resist attack by mould/fungus | Sample buried in moist sawdust infected with mould spores (Aspergillus, Penicillium etc.), kept at 27±2°C for 3 weeks, then tested for glue shear strength (Part 4) | Must meet the minimum glue shear strength required for that plywood grade | IS 1734 (Part 4)-1983 – Glue shear strength (test specimen dimensions and reporting) |
| 10 | pH Value | Check acidity/alkalinity of the wood near the glue line (affects strength over time) | Grind wood near glue line, mix 1g powder with 5ml distilled water, let stand 72 hours, measure pH; repeat every 24 hrs until readings stabilize (within 0.05 pH units) | No pass/fail – pH value is simply recorded | None referenced |
| 11 | Tensile Strength | Check maximum pulling/stretching force the plywood can take before breaking | Shaped sample pulled apart in a machine at 1mm/minute until it breaks | No fixed pass/fail – maximum stress, stiffness etc. are recorded and compared to grade requirements | None referenced |
| 12 | Compressive Strength | Check how much squeezing/crushing force the plywood can take | Rectangular sample compressed in a machine until it crushes or fails | No fixed pass/fail – maximum crushing stress is recorded and compared to grade requirements | None referenced |
| 13 | Static Bending Strength (Central Loading & Two-Point Loading) | Check how much bending force the plywood can take before breaking, and how stiff it is | A strip of plywood is supported at both ends and a load is applied (at center, or at two points) until it breaks, while deflection is measured | No fixed pass/fail – strength, stiffness values are recorded and compared to grade requirements | None referenced |
| 14 | Scarf Joint Strength (Mandrel Test) | Check the strength of a glued joint where two pieces of veneer are joined at an angle | Sample with the joint is bent around a cylindrical mandrel (rod) of diameter = 200x the plywood thickness; checked for cracking/separation at the joint | Reported as % of wood fibres remaining stuck (compared with a sample without a joint) – for aircraft plywood, if more than 20% of test pieces break, the whole batch is rejected | None referenced |
| 15 | Scarf Joint Strength (Tensile Test) | Check pulling strength of a joined section (for plywood thicker than 3mm) | Sample with joint is pulled apart like in Part 9 tensile test; compared with a sample without the joint | No fixed numeric pass/fail – breaking load and location of failure recorded and compared with un-jointed sample | IS 1734 (Part 9)-1983 – Determination of tensile strength |
| 16 | Panel Shear Strength | Check how the whole panel resists shearing/twisting forces along its diagonal | Square panel mounted with pins/blocks at corners; force applied diagonally until failure | No fixed pass/fail – shear stress value recorded and compared to grade requirements | None referenced |
| 17 | Plate Shear Strength | Check how the plywood resists twisting forces (shear stiffness) | Square plate supported and loaded at diagonal corners; deflection measured at multiple points; test repeated with panel rotated 90° | No pass/fail – shear modulus (stiffness value) is calculated and reported | None referenced |
| 18 | Central Loading of Plate Test (Stiffness) | Check overall stiffness of a plywood sheet when pressed in the center | Square plate held in a frame (edges supported, or all edges clamped), load applied at center with a steel ball until failure, deflection measured | No pass/fail – stiffness value calculated and reported | None referenced |
| 19 | Vibration of Plywood Plate Test | Check stiffness/quality using vibration (without damaging the sample) | A magnet vibrates the plate at different frequencies until it resonates (vibrates strongly); resonant frequency is recorded | No pass/fail – resonant frequency and stiffness value reported | None referenced |
| 20 | Long Time Loading Test (Creep Test) | Check how much the plywood bends/sags over time under a constant load (sustained weight) | A strip is loaded with 30% of its maximum bending load (calculated as per Part 11) and the sagging (deflection) is measured over time (every 10 min, then hourly, then daily) for up to a week or until it breaks | No pass/fail – creep rate and a "coefficient of sustained loading" value are calculated and reported | IS 1734 (Part 11)-1983 – Static bending strength (used to calculate max load); IS 1734 (Part 10)-1983 – Compressive strength (used for instantaneous breaking load in sustained loading test) |
| 21 | Impact Resistance – Surface | Check if the plywood surface dents or cracks from a sudden impact | A 5cm steel ball (450±25g) is dropped from 100cm height onto 5 different spots on the plywood; any dent is measured | No fixed pass/fail value – dent depth and any cracking/tearing is recorded | None referenced |
| 22 | Impact Resistance – Panel (Whole Board) | Check how strong the whole panel is against a sudden heavy blow | A 5kg weight with a rounded tip is dropped from increasing heights (10mm steps) onto the center of a supported panel until it breaks through | No fixed pass/fail number – the height at which the panel breaks is the "impact strength" (if it survives 1000mm with 5kg, a 10kg weight is used from 500mm) | None referenced |
| 23 | Nail and Screw Holding Power | Check how well the plywood grips nails and screws | Nails (50mm) and screws (40mm, with pre-drilled hole) are driven into a thick stack of plywood, then pulled out at 2mm/minute; max force to pull out is recorded | No fixed pass/fail – average pull-out force is recorded and compared to grade requirements | IS 723-1972 – Specification for steel countersunk head wire nails; IS 6761-1972 – Specification for countersunk head screws with hexagon socket |
| 24 | Acidity and Alkalinity Resistance | Check if the plywood surface is damaged by mild acid or alkali (e.g., from goods stored inside) | A few drops of 5% acid solution or 1% alkaline solution placed on the surface, covered for 6 hours, then washed and dried for 24 hours | No fixed pass/fail – any blistering, cracking, softening, or colour change is simply noted and reported | None referenced |
Most of these tests don't have a simple "pass" or "fail" number on their own. FlaerPly Masterclass has simplified this for non-technical users and more importantly recommends the most fool-proof way to test plywood for your interiors.
Conclusion
FlaerPly's Pressure Test is a quick shortcut to test multiple capabilities of plywood that make it suitable for using in home interiors. We have been informed by our customers that, bad players in the industry only mention the technical way of testing plywood that cannot be done in short time or will need a lab to so it, allowing them to claim superior quality without allowing the buyers to test the plywood.
Most of these tests don't have a simple "pass" or "fail" number on their own — the actual numbers (minimum acceptable density, strength, glue adhesion etc.) are defined separately in the specific plywood product standards (e.g., IS 303 for commercial plywood, IS 710 for marine plywood) based on the intended grade and use. This FlaerPly Masterclass on Plywood Testing, only tells you how to perform and measure each test, and cross-refers to other parts of itself and a few other IS standards for specimen sizes and hardware specifications.
