ISO 55:1977 pdf download – Seedlac – Specification
A.2.3.1 Place 1 25 ml of the alcohol (A.2.1 ) in the flask (A.2.2.3) and a new cartridge (A.2.2.5) in the siphon tube (A.2.2.2). Introduce the siphon tube into the flask and connect it to the condenser (A.2.2.1), making sure that there i s ample flow of cold water through the condenser. Adjust the rate of heating so as to give a cycle of filling and emptying in the siphon tube every 2 min and extract for 30 min. Dry the cartridge in the oven (A.2.2.10) at 1 00f2OC. At the end of 2 h, weigh it in a tared weighing bottle (A.2.2.61, which has been kept in the desiccator over sulphuric acid (A.2.2.9), lifting the stopper of the bottle momentarily before weighing. Repeat the operations of drying, for periods of 1 h, and weighing, until the loss in mass between two successive weighings does not exceed 2 mg.
A.2.4.1 Before analysis, thoroughly mix the test sample (see F.3.1 ) by rolling on paper, a t least ten times, to ensure uniformity of the test sample. Weigh, directly from the paper, 4 3 to 5,5 g of the sample, to an accuracy of 0,Ol g, place in the beaker (A.2.2.8), add 1 25ml of the alcohol (A.2.1 ), cover with a watch-glass and place on the hot water bath (A.2.2.7) (see figure 2). Boil the solution vigorously for 30 min to ensure complete solution of the seedlac and dispersion of wax. Keep the volume of alcohol constant by adding hot alcohol from a wash bottle, washing down the sides of the beaker.
A.2.4.2 Meanwhile, place an extracted and weighed cartridge in the filter tube. Maintain the hot water around the tube at not less than 90 “C. Wet the cartridge with hot alcohol and decant the boiling solution into the heated cartridge until the beaker is nearly empty.
A.2.4.4 Transfer the cartridge containing the insoluble matter to the extraction apparatus, place 1 25 ml of alcohol in the extraction flask and connect up the apparatus. Start the water flowing thraugh the condenser, making sure that there is an adequate supply for efficient condensation. Light the burner and time the extraction from the first emptying of the siphon, running the extraction for exactly 1 h. Adjust the rate of heating so that a complete filling and emptying of the siphon tube takes place every 2 min, as determined by a stoplwatch or preferably by a good two- minute sand-glass, one for each extraction apparatus. A;2.4.4.1 In this way exactly 30 cycles per hour are accomplished. If this cycle rate is not meticulously main- tained, neither check results on duplicate samples in the same laboratory nor concordant figures from one labora- tory to another can be obtained, even when working on the same standard sample. It is also necessary to protect the apparatus from draughts while in operation, otherwise the proper cycle rate cannot be maintained.
A.2.4.4.2 Occasionally, seedlacs are encountered which do not yield the required number of 30 siphonings per hour, due to slow filtration, in these cases, continue the ex- traction until 30 siphonings have been accomplished or repeat the test with a 2 g test portion and report the sample as abnormal or slow filtering.
A.2.4.5 Remove the cartridge.After drying for 2 h, place it in the weighing bottle, cool in the desiccator over sulphuric acid and weigh, removing the stopper momentarily just before weighing. Repeat the operations of drying, for periods of 1 h, and weighing, until the loss in mass between two successive weighings does not exceed 2 mg. From the mass of the residue and the mass of the sample, calculate the percentage of in- soluble matter. Use the lowest mass in the caiculation.