BS EN ISO 4630:2015 pdf download – Clear liquids — Estimation of colour by the Gardner colour scale
This International Standard specifies a method for estimating the colour of optically clear,yellow/brownish coloured liquid products by means of the Gardner colour scale using colour-measuringinstruments.The method uses the Gardner colour scale described in Annex A.
lt is applicable to drying oils, varnishes and solutions of fatty acids, polymerized fatty acids, resins, talloil, tall oil fatty acids, rosin and related products.The results might be invalid if other products are tested.The method described provides a more precise way of measuring Gardner colour than a visual samplecomparison using human eyes.It is applicable to products having colours from Gardner 1 toGardner 1i8.The Gardner scale is not applicable to products with colours darker than 18.For products with colourslighter than Gardner 1 the method specified in ISO 6271 applies.
The following referenced documents,in whole or in part, are normally referenced in this document andare indispensable for its application.For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including any amendments) applies.
ISO 3696,Water for analytical laboratory use — Specification and test methods
IS0 5725-2,Accuracy (trueness and precision) of measurement methods and results —Part 2: Basic methodfor the determination of repeatability and reproducibility of a standard measurement method
ISO 13632,Binders for paints and varnishes — Rosin — Sampling and sample preparation for colourmeasurement
ISO 15528,Paints, varnishes and raw materials for paints and varnishes — SamplingCIE Publication No.15:2004, Colorimetry
The colour of a liquid sample is measured using an instrument capable of measuring transmitted colourand reporting inGardner colours or in a colour system that can be converted into Gardner colours.
4 Apparatus and materials
4.1 Colour-measuring instrument, spectrophotometer capable of measuring transmitted colour(0°/180° geometry) and reporting the results in the Gardner colour scale. If such an instrument is notavailable, one may be used which is capable of measuring transmitted colour and reporting in tristimulusvalues using standard illuminant C and the 2° observer, described in CIE Publication No.15:2004.
4.2Absorption cells, 10 mm light path length recommended, unless a different path length is specifiedby the instrument manufacturer or
4.3 Glass tubes,11 mm path length. Glass test tubes designed for a specific instrument may be used.
Take a representative sample of the product to be tested, as described in ISO 15528.
In the case of rosin, take a representative sample, as specified in ISO 13632.
Baseline calibration of the instrument shall be performed following the instrument manufacturer’s recommendations.
If the material to be tested is cloudy, first filter it (see Note). Then, using the same type of glass tube or absorption cell as used for the baseline calibration, fill the glass tube or absorption cell with the product. Take care not to touch the measurement area of the glass tube or absorption cell.
If the material shows any visual haziness, remove the haze e.g. by filtration, centrifugation, heating,ultrasonic treatment or any other suitable means (see Note).
If the haziness cannot be removed, the measured value will be unreliable.
Then, using the same type of glass tube or absorption cell as used for the baseline calibration, fill the glass tube or absorption cell with the product. Take care not to touch the measurement area of the glass tube or absorption cell.
Avoid creating air bubbles when filling the glass tube or absorption cell. If air bubbles are formed and remain trapped, remove them by heating, vacuum, ultrasonic treatment or any other suitable means (see Note).
NOTE Some sample pre-treatments can change the colour.
Insert the glass tube or absorption cell in the instrument and measure the Gardner colour, following the instrument manufacturer’s recommended procedure.
Regular checks as per the instrument manufacturer’s recommendations should be carried out. These will normally be in the form of checks with certified reference materials.
7 Expression of results
Report the colour in Gardner colour units to the nearest tenth of a Gardner unit as given by the instrument.
The precision of the test method was determined by interlaboratory testing in accordance with ISO 5725-2.
Three different materials were tested by 13 laboratories.BS EN ISO 4630 pdf download.