ABSTRACT
The mass of the roll is determined by weighing using any suitable means and deducting the mass of the tube or holder from the gross mass recorded. From the mass, width, and length so determined, the mass per unit area can be calculated if required. Normally this weight would be obtained from a smaller cut piece, representative of the roll taken on line during processing as part of a quality control check. The method used [7] involves a balance and a standard-sized cutter giving a test piece of 100 square centimeters. Calculation of grams per square meter (gsm) is therefore easily carried out. Samples can be taken across the width, the results averaged, and corrections made to the processing conditions if remedial action needs to be made due to variation edge to center during manufacture. Coating mass can be determined if the weight of the fabric is known. If not,then the cloth has to be carefully removed from the coating using a suitable solvent system or stripping medium. Often the fabric can be removed by moistening with liquid, but if the coating needs to be dissolved away, then Soxhlet extraction or immersion and agitation may be used. It is clearly important to use a solvent which does not affect the fabric. Drying, reconditioning, and weighing the fabric enable the calculation to be done. The polymer coating will also dictate the type of solvent to be used. Safe methods of working and the use of personal protective clothing equipment may be required,and certain solvents may need other precautionary measures. Safety statements are now being written into standards to ensure good working practices.
