ISO 55-1977 pdf download – Seedlac – Specification

02-19-2022 comment

ISO 55-1977 pdf download – Seedlac – Specification.
O INTRODUCTION 0.1 The usual trade descriptions of seedlac are based on the Indian names of the host trees, the season of cropping the sticklac, visual differences or a combination of any of these. The use of these grade designations led to con- fusion and some marketing difficulties. When ISO/R 55 was prepared in 1957, it was decided to adopt only seven grades which were independent of the names of host trees or seasons. However, the expectation that the I S 0 grades for seedlac would be increasingly adopted in trade and ultimately replace the traditional grade designations has not come about. A new system has theïefore been adopted in this International Standard so that seedlac can now be completely identified by a combination of the IS0 grade and the trade grade. In this revision, it has been found possible to reduce the number of I S0 grades from seven to five. 0.2 For matter insoluble in hot alcohol, two limits are prescribed, in line,with trade practice : a basic limit and a relaxed limit. The’relaxed limit shall be the limit for rejection. 0.3 The requirement for non-volatile matter soluble in cold alcohol has not been retained as this requirement is applied in practice to waste products of lac only. 0.4 One of the requirements for seedlac, namely that for matter insoluble in hot alcohol, is included in this Inter- national Standard as an essential clause. The remainder, namely those for volatile matter (moisture), colour, bleach index and bleachability, matter soluble in water, wax and ash, are optional. 0.5 For determination of bleach index and bleachability, two methods are practised. One has been developed in India and the other in the U.S.A. The method to be followed for the determination of bleach index and bleachability shall be subject to agreement between the purchaser and the supplier.
0.6 For the purpose of deciding whether a particular requirement of this International Standard i s complied with, it is necessary for the final value, observed or calcu- lated, expressing the result of test or analysis to be rounded off to the same number of places as that in the specified vatue, it being always understood that the analyst Will carry out his determination to a t least one place more than in the specified value. 1 SCOPE AND FIELD OF APPLICATION 1 .I This International Standard specifies requirements and methods of test for seedlac. 1.2 This International Standard is intended chiefly to cover the technical provisions for guiding the purchase of the material, but does not include all the necessary pro- visions of a contract. 1.3 The limits specified in this International Standard are limits for rejection (see 0.2). . . 2 DEFINITIONS For- the purposes of this International Standard, the follow- ing definitions apply : 2.1 sticklac : The natural product of lac insects. 2.2 seedlac : The product obtained by washing crushed sticklac. 2.3 approved sample : The sample agreed upon between the purchaser and the vendor as the standard for colour and appearance.

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