1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-21434-0 SANS 6873:2008Edition 1ISO 6873:1998Edition 2 SOUTH AFRICAN NATIONAL STANDARD Dental gypsum products This national standard is the
4、 identical implementation of ISO 6873:1998 and is adopted with the permission of the International Organization for Standardization. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 6873
5、:2008 Edition 1 ISO 6873:1998 Edition 2 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee SABS SC 106B, Dental equipment and materials Dental materials, in accordance with procedures of the SABS Standards Division, in compliance w
6、ith annex 3 of the WTO/TBT agreement. This SANS document was published in September 2008. AReference numberISO 6873:1998(E)INTERNATIONALSTANDARDISO6873Second edition1998-03-01Dental gypsum productsProduits dentaires base de gypseSANS 6873:2008This s tandard may only be used and printed by approved s
7、ubscription and freemailing clients of the SABS .ISO 6873:1998(E) ISO 1998All rights reserved. Unless otherwise specified, no part of this publication may be reproducedor utilized in any form or by any means, electronic or mechanical, including photocopying andmicrofilm, without permission in writin
8、g from the publisher.International Organization for StandardizationCase postale 56 CH-1211 Genve 20 SwitzerlandInternet centraliso.chX.400 c=ch; a=400net; p=iso; o=isocs; s=centralPrinted in SwitzerlandiiContentsPage1 Scope 12 Normative reference . 13 Definition. 14 Classification and designation 15
9、 Requirements . 25.1 Quality . 25.2 Fluidity at pouring time (Type 1 materials only). 25.3 Setting time 25.4 Linear setting expansion 25.5 Fracture (Type 1 materials only) . 25.6 Compressive strength . 25.7 Reproduction of detail 26 Sampling. 36.1 Sampling 36.2 Test conditions 36.3 Mixing method . 3
10、7 Test methods 37.1 Inspection 37.2 Fluidity at pouring time for Type 1 materials 37.3 Setting time 47.4 Linear setting expansion 67.5 Fracture . 7SANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO ISO 6873:1998(E)iii7.6 Compre
11、ssive strength 77.7 Reproduction of detail 88 Packaging, marking and information to be supplied by themanufacturer. 108.1 Packaging 108.2 Labelling 108.3 Information to be supplied by the manufacturer 11SANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailin
12、g clients of the SABS .ISO 6873:1998(E)ISOivForewordISO (the International Organization for Standardization) is a worldwidefederation of national standards bodies (ISO member bodies). The work ofpreparing International Standards is normally carried out through ISOtechnical committees. Each member bo
13、dy interested in a subject for whicha technical committee has been established has the right to be representedon that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISOcollaborates closely with the International Electrotech
14、nical Commission(IEC) on all matters of electrotechnical standardization.Draft International Standards adopted by the technical committees arecirculated to the member bodies for voting. Publication as an InternationalStandard requires approval by at least 75 % of the member bodies castinga vote.Inte
15、rnational Standard ISO 6873 was prepared by Technical CommitteeISO/TC 106, Dentistry, Subcommittee SC 2, Prosthodontic materials.This second edition cancels and replaces the first edition (ISO 6873:1983),which has been technically revised.SANS 6873:2008This s tandard may only be used and printed by
16、approved subscription and freemailing clients of the SABS .INTERNATIONAL STANDARD ISO ISO 6873:1998(E)1Dental gypsum products1 ScopeThis International Standard gives a classification of, and specifies requirements for, gypsum products used fordental purposes such as making oral impressions, moulds,
17、casts or dies. It specifies the test methods to beemployed to determine compliance with these requirements. It also includes requirements for the labelling ofpackaging and for adequate instructions to accompany each package.2 Normative referenceThe following standard contains provisions which, throu
18、gh reference in this text, constitute provisions of thisInternational Standard. At the time of publication, the edition indicated was valid. All standards are subject torevision, and parties to agreements based on this International Standard are encouraged to investigate thepossibility of applying t
19、he most recent edition of the standard indicated below. Members of IEC and ISO maintainregisters of currently valid International Standards.ISO 3696:1987, Water for analytical laboratory use Specification and test methods.3 DefinitionFor the purposes of this International Standard, the following def
20、inition applies.3.1dental gypsum productdental product composed essentially of hemihydrate of calcium sulfate and any necessary modifiersNOTE Colouring matter and flavouring, if present, are regarded as necessary modifiers.4 Classification and designationThe five types of gypsum product used in dent
21、istry are classified in accordance with this International Standard asfollows:Type 1: Dental plaster, impressionType 2: Dental plaster, modelType 3: Dental stone, modelType 4: Dental stone, die, high strength, low expansionType 5: Dental stone, die, high strength, high expansionSANS 6873:2008This s
22、tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 6873:1998(E)ISO25 Requirements5.1 QualityThe material shall be uniform and free from foreign matter and lumps, and when mixed according to themanufacturers instructions shall produce a homogeneous
23、mix.5.2 Fluidity at pouring time (Type 1 materials only)When tested according to 7.2 at a pouring time of 1,25 min, the fluidity of type 1 materials shall be equal to orgreater than 70 mm.5.3 Setting timeWhen tested according to 7.3, the setting time of type 1 materials shall be in the range of 2,5
24、min to 5,0 min and thesetting time of all material types shall be within 20 % of the value claimed by the manufacturer in 8.3 c). If themanufacturer claims a range of setting time, then the midpoint of this range is taken as the value claimed by themanufacturer.5.4 Linear setting expansionWhen teste
25、d according to 7.4, the setting expansion shall be within the range listed in table 1.Table 1Compressive strengthType Setting expansion range MPa% min. max.1 0 to 0,15 4,0 8,02 0 to 0,30 9,0 3 0 to 0,20 20,0 4 0 to 0,15 35,0 5 0,16 to 0,30 35,0 5.5 Fracture (Type 1 materials only)When broken in acco
26、rdance with 7.5, Type 1 impression plaster shall break with a clean fracture and be readilyreassembled to form the shape and size of the original unbroken specimen.5.6 Compressive strengthWhen tested according to 7.6, the compressive strength shall meet the requirements of table 1.5.7 Reproduction o
27、f detailTypes 1 and 2 when tested according to 7.7, line (c) in figure 3 a) shall be reproduced.Types 3, 4 and 5 when tested according to 7.7, line (a) in figure 3 a) shall be reproduced.SANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailing clients of the
28、 SABS .ISOISO 6873:1998(E)36 Sampling6.1 SamplingMaterial selected for testing shall be from one batch and shall not be tested beyond its “Use Before“ date 8.2.1 g).Powder from broken or damaged containers shall not be used for testing.6.2 Test conditionsAll mixing and testing of the dental gypsum p
29、roduct shall be carried out at (23 2) C and (50 10) % relativehumidity. All apparatus and instruments used in mixing and testing shall be clean, dry and free from particles ofgypsum. Before testing begins, material and test apparatus shall be held for at least 15 h at the test temperature.6.3 Mixing
30、 methodMix by one of the methods (hand or mechanical) specified by the manufacturer in the instructions 8.3 b), usingwater which meets the requirements of ISO 3696.7 Test methods7.1 InspectionDetermine compliance with the requirements given in 5.1, 5.5 and 5.7 by visual inspection (without magnifica
31、tion,unless as stated in 7.7).7.2 Fluidity at pouring time for Type 1 materials7.2.1 Apparatus7.2.1.1 Cylindrical mould, clean and dry, having a length of (50,0 0,1) mm and an inside diameter of(35,0 0,1) mm constructed from a corrosion-resistant, non-absorbent material.7.2.1.2 Glass plate, clean, d
32、ry and smooth, with sides of length at least 100 mm.7.2.1.3 Means of measuring the major and minor diameters of the slumped mix to the nearest millimetre, such asa micrometer caliper.7.2.2 ProcedureRest the glass plate (7.2.1.2) on a surface that is free of vibration. Place the mould (7.2.1.1) uprig
33、ht on the centre ofthe plate. Add (100 0,1) g of the sample to the manufacturers recommended quantity of water and mix asdescribed in 6.3. Completely fill the mould and level off the mixed material so that it is flush with the top of themould. At 1,25 min after the start of mixing, lift the mould ve
34、rtically from the plate at a rate of approximately 10 mm/sand allow the mix to slump or spread over the plate. One minute after the mould is lifted, measure the major andminor axes of the slumped material to the nearest millimetre. Record the average of these two diameters as thefluidity at pouring
35、time.7.2.3 EvaluationCarry out the test two times. If both average values meet the requirements for fluidity at pouring time listed in 5.2,then the material meets the requirement for fluidity of this International Standard. If neither meets the requirementlisted in table 1, then the material fails t
36、o meet the requirement. If one average value meets the requirement forSANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 6873:1998(E)ISO4fluidity and the other fails, carry out three more tests. If all three of these average va
37、lues meet the requirement forfluidity (5.2), then the material meets the requirement for fluidity of this International Standard. Otherwise it fails.7.3 Setting time7.3.1 Apparatus7.3.1.1 Vicat needle apparatus, an example of which is shown in figure 1, meeting the following requirements:a) Vicat ne
38、edle (C), 50 mm long, of circular cross-section and with a diameter of (1 6 0,05) mm.b) Rod (B), of approximate dimensions 270 mm long and 10 mm in diameter.c) Total mass of the rod and needle (A, B and C in figure 1) shall be (300 6 1) g.d) Scale (D), graduated in millimetres.e) Baseplate (H) of pl
39、ate glass, measuring about 100 mm 100 mm.7.3.1.2 Clean, dry conical ring mould, constructed from a corrosion-resistant, nonabsorbent material, having aninside diameter of 70 mm at the top and 60 mm at the base, and a height of 40 mm.7.3.2 ProcedureAdd 400 g of the sample to the manufacturers recomme
40、nded quantity of distilled water and mix as described in 6.3.Fill the mould (7.3.1.2) completely and level the specimen flush with the top of the mould. Using the Vicat needleapparatus (7.3.1.1) and beginning 1 min or 2 min prior to the anticipated setting time (usually at the loss of gloss orexcess
41、 water), allow the needle to penetrate the mix at (15 1) s intervals as follows.a) Move the mould to allow the next penetration to be in a new area which is at least 5 mm from the mould walland from any other penetration mark.b) Wipe the needle clean and then bring its tip into contact with the surf
42、ace of the mix and lock the rod in positionwith the lock screw.c) Read the scale and, at the appropriate time, release the rod. Note the new position of the scale and calculatethe depth of penetration.d) Record the setting time as the total time from the start of mixing to the time when the needle f
43、irst fails topenetrate the specimen to a depth of at least 2 mm.7.3.3 EvaluationCarry out the test two times. If both measurements meet the requirement for setting time (5.3), then the materialmeets the requirement for setting time of this International Standard. If neither meets the requirement for
44、 settingtime, then the material fails to meet the requirements for setting time of this International Standard. If onemeasurement meets the requirement for setting time and the other fails, carry out three more tests. If all three ofthese measurements meet the requirement for setting time, then the
45、material meets the requirement for setting timeof this International Standard. Otherwise the material fails.SANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISOISO 6873:1998(E)5KeyA Additional weightB RodC Vicat needleD ScaleE Lo
46、ck screwF Support bracketG Conical ring mouldH BaseplateFigure 1 Typical Vicat needle apparatus (see 7.3.1.1)SANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 6873:1998(E)ISO67.4 Linear setting expansion7.4.1 Apparatus and mat
47、erials7.4.1.1 Extensometer, as shown in figure 2, and producing a specimen with a length of 100 mm. The apparatus isfitted with a device which measures change in length to within 0,01 mm and exerts a measuring force which is nogreater than 0,8 N. The internal cross-section of the trough shall be an
48、isosceles triangle with internal side lengthsof (30 1) mm. One end of the trough shall be blocked with an immovable endpiece and the other with a movableendpiece having a mass of (200 10) g.On the inside of this trough a horizontal line shall be scribed so as to define a triangle with included sides
49、 of length(25 1) mm.7.4.1.2 Polytetrafluoroethylene (PTFE) sheet; 0,1 mm to 0,2 mm thick.7.4.1.3 Mould-release agent.Dimensions in millimetresKeyA TroughB PTFE sheetC Movable endpieceD Gauge supportE Dial gauge or equivalentF Immovable endpieceFigure 2 Example of suitable extensometerSANS 6873:2008This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISOISO 6873:1998(E)77.4.2 ProcedureLine the trough with the PTFE sheet (7.4.1.2).Apply the m
