ISO INTERNATIONAL STANDARD 16985 First edition 2003-05-15 Wood-based panels Determination of dimensional changes associated with changes in relative humidity Panneauxabasedebois-Determinationdesvariations dimensionnelles sous I'influence devariations deI'humidite relative Reference number ISO 16985:2003(E) ISO @ISO2003 ISO16985:2003(E) Foreword IsO (the International Organization for Standardization)is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has been non-governmental, in liaison with IsO, also take part in the work. IsO collaborates closely y with the InternationalElectrotechnicalCommission(lEC)onallmattersofelectrotechnicalstandardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval byat least 75% of the memberbodies casting avote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO16985was prepared byTechnical CommitteeISO/TC 89,Wood-based panels.ISO16985 is basedon European Standard EN 318. ISO 2003— All rights reserved ili INTERNATIONAL STANDARD ISO16985:2003(E) Wood-based panels Determination of dimensional changes associated with changes in relative humidity 1 Scope This International Standard specifies a method for the determination of dimensional changes in wood-based panels, due to variations in relative humidity. 2 Normativereferences references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Iso16979,Wood-based panels-Determinationofmoisture content so16999,Wood-basedpanels—Samplingandcuttingoftestpieces 3 Principle adsorption; this gives rise to a hysteresis effect. In order to obtain the true dimensional change, this is measured between 65 % and 85 % relative humidity in adsorptionandbetween65%and30%relativehumidityindesorption 4 Apparatus 4.1Balance, as described in ISO 16979. 4.2 length-measuring equipment is shown in Figure 1. 4.3 Calibration bar, corrosion-resistant metal bar of sufficient length and shape to calibrate the length- measuring equipment. The length of the calibration bar shall be known to within 0,01 mm. 4.4 Climate chamber(s), capable of maintaining the required temperature at ± 1 C and relative humidity at ± 3 %. ISO 2003—All rights reserved 1 ISO16985:2003(E) Dimensions in millimetres 5 R5 300 Figure1-Exampleoflength-measuringequipment 4.5 Drying oven, ventilated and capable of being controlled at (103±2)°C. 4.6 Hygrometer, with an accuracy of ± 1 % relative humidity to measure and record the relative air humidity in the climate chamber. 4.7 Thermometer, with an accuracy of ±O,5 °C to measure and record the temperature in the climate chamber. Test pieces Dimensions of test pieces are (300 ± 1) mm × (50 ± 1) mm × t (panel thickness). From each panel, two sets of four test pieces shall be cut in each panel direction. The general conditions for sampling of the test pieces shall be in accordance with ISO 16999. 6 Procedure 6.1 Test-piece preparation 6.1.1 General The test pieces shall be prepared with suitable markings to ensure that the measurement will be carried out at the same position each time. 6.1.2 Thickness-measuring points The marks are placed on the centre-line of the test piece 50 mm from the ends and at the mid-point, as shown in Figure 2. Ink marks on the surface of the test piece are considered to be adequate. Other types of mark