ISO 57-1975 pdf free.Bleached lac — Specification.
1.1This International Standard specifies the requirementsand methods of test for bleached lac in any form that maybe agreed upon between the purchaser and the vendor.
1.2This International Standard is intended chiefly tocover the technical provisions for guiding the purchase ofthe material，but does not include all the necessaryprovisions of a contract.
1.3The limits specified in this International Standard arenot to be exceeded.
DEFINITIONS:For the purposes of this International Standard,thefollowing definitions apply :
2.1 sticklac : The natural product of lac insects.
2.2seedlac : The product obtained by washing crushedsticklac.
2.3shellac : The product obtained by refining seedlac byheat processes or by both heat and solvent processes.
2.4bleached lac : The product obtained by subjectingseedlac or shellac in solution to a process of bleaching andthen recovering the product in a solid form.
2.5regular (cloudy or waxy) bleached lac : The ordinarytype of bleached lac from which wax has not beenremoved.
2.6rofined (transparent or wax-free) bleached lac : Thetype of bleached lac from which wax has been removedduring the process of manufacture.
2.7approved sample : The sample agreed upon betweenthe purchaser and the vendor as the standard for colour andappearance.
3.FORM:The form of bleached lac is subject to agreement betweenthe purchaser and.the vendor.
4.1 Bone-dry bleached lac shall contain not more than 6 %of volatile matter (moisture) as determined by the methoddescribed in annex A.
4.2The percentage of volatile matter (moisture) present insurface-dry (air-dry)bleached lac shall be subject toagreement between the purchaser and the vendor and shallbe determined by the method’ described in annex A(see 0.5).The percentage of volatile matter (moisture) in wetbleached lac shali be subject to agreement between thepurchaser and the vendor and shall be determined by themethod described in annex A (see 0.5).
Matter insoluble in hot alcohol shall be determined byeither of the methods described in annex B,as agreedbetween the purchaser and the vendor.
The appearance and colour of bleached lac shall not beinferior to that of the approved sample when judged byvisual examination. Alternatively the colour in solutionmay be tested by either of the methods described inannex C, as agreed between the purchaser and the vendor.13.1 The acid value of bleached lac shall be subject toagreement between the purchaser and the vendor and, whenspecified,it shall be determined by the method described inannex K(see 0.3).
13.2The mineral acid content of bleached lac shall besubject to agreement between the purchaser and the vendorand, when specified,it shall be determined by the methoddescribed in annex L (see 0.4).
A requirement for the absence of free chlorine or peroxidesshall be subject to agreement between the purchaser andthe vendor. When specified,the aqueous extract of thematerial shall not show the presence of free chlorine orperoxides when tested by the method described inannex M.ISO 57 pdf download.