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1、AS 3894.42002 Standards Australia 1 Australian StandardTM Site testing of protective coatings Method 4: Assessment of degree of cure PREFACE This Standard was prepared by the Australian members of the Joint Standards Australia/Standards New Zealand Committee CH-003, Paints and Related Materials, to
2、supersede AS 3894.11991. After consultation with stakeholders in both countries, Standards Australia and Standards New Zealand decided to develop this Standard as an Australian Standard rather than an Australian/New Zealand Standard. FOREWORD A test for the degree of cure will assist in determining
3、whether a coating is suitable for service and whether quality control procedures, such as adhesion and pinhole testing, may be performed. The firmness of the surface of a coating or its solvent resistance does not necessarily determine the degree of cure, as a coating may achieve surface dryness wit
4、h a degree of hardness and still be soft underneath. Some coatings, such as elastomeric urethane, are permanently soft and pliable yet fully cured. These field tests provide a guide for use with other tests in the AS/NZS 3894 series. METHOD 1 SCOPE This Standard provides guidance on practical proced
5、ures, for use in the field, to assess the degree of cure or through-dry in coatings. Applicable coatings include those that dry by oxidation (e.g., alkyd), solvent evaporation (e.g., lacquers such as chlorinated rubber), those that set by chemical reaction with a liquid curing agent (e.g., epoxy) an
6、d those that react with the atmosphere (e.g., inorganic zinc). 2 DEFINITIONS For the purpose of this Standards the definition given in AS 2310 apply. 3 REFERENCED DOCUMENTS The following documents are referred to in this Standard: AS/NZS 1580Paints and related materials Methods of test 1580.405.1Met
7、hod 405.1:Determination of pencil hardness of paint film 2310Glossary of paint and painting terms AS 3894.4 Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 Standards A.au 2 AS/NZS 3750Paints for steel structures 3750.15Part 15:Inorganic zinc silicate paint ASTM D 2240Standard
8、test method for rubber propertyDurometer hardness D 2583Standard test method for indentation hardness of rigid plastics by means of a Barcol impressor D 4752Standard test method for measuring MEK resistance of ethyl silicate (inorganic) zinc-rich primers by solvent rub 4 GENERAL Four methods of asse
9、ssing the degree of cure in the field are described in Clauses 4, 5, 6 and 7 as Methods A, B, C and D respectively. Some of these test procedures may damage the coating to be tested, particularly in the early cure stage. The preparation of test panels, appropriately coated, prepared at the same time
10、 and held under identical conditions, may be used for testing and so avoid costly repairs to the coating undergoing assessment. The surface hardness of all coatings, with the exception of inorganic zinc coatings, is affected by temperature. If testing is performed outside the range 1525C, the manufa
11、cturers advice should be sought. Table 1 shows the test methods recommended for assessment of the degree of cure on various types of coatings. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 .au Standards Australia 3 TABLE 1 TEST METHODS APPLICABLE TO VARIOUS COATINGS CoatingT
12、est * Reference test method Comments AlkydPencil hardnessAS/NZS 1580.405.1Limits set by the coating manufacturer. Limited field use DurotestLimits set by the coating manufacturer Rub test (mineral turps)Easy to use. Limits set by the coating manufacturer Chlorinated rubber, vinylPencil hardnessAS/NZ
13、S 1580.405.1Limits set by the coating manufacturer. Limited field use DurotestLimits set by the coating manufacturer Epoxy, polyurethane, cross- linked acrylic Rub test (MEK or nominated solvent) Easy to use Inorganic zincRub test (MEK) solvent-borne material ASTM D 4752Easy to use DurotestLimits se
14、t by the coating manufacturer Pencil hardnessAS/NZS 1580.405.1Refer AS/NZS 3750.15 Ultra high-build coatings greater than 600 m; epoxy, polyester, vinylester, polyurethane Barcol 935 hardness impressor Limits set by the coating manufacturer. Easy to use Elastomeric coatingsShore A durometer hardness
15、 tester ASTM D 2240Easy to use *These tests will damage uncured coatings, and may damage cured coatings if applied indiscriminately. The tests are applied to the outermost layer of the coating. Before proceeding with a test, where recommended by the paint manufacturer, it may be necessary to determi
16、ne that there is no entrapped solvent within the deeper layers of the coating. 5 METHOD APENCIL HARDNESS TEST 5.1 Principle The hardness of the surface is determined by marking it with pencil leads of various grades, e.g., 2H, HB, 3B, and then examining the coating for the presence or absence of dam
17、age. The method of test is similar to that outlined in AS/NZS 1580.405.1; however, the procedure for the selection of leads is reversed, using the softest leads first to minimize damage to the coating. 5.2 Apparatus 5.2.1 Pencil leads A set of pencil leads with a diameter of 2 mm to fit a clutch-typ
18、e pencil lead holder. The following leads shall be included in the set: 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H and 8H (6B being the softest and 8H the hardest). Each lead shall be scratched by the next hardest lead above it in the series. 5.2.2 Pencil lead holder A clutch-type mecha
19、nical lead holder suitable for use with the leads specified. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 Standards A.au 4 5.2.3 Abrasive paper Of No. P600 grain size. 5.3 Preparation of leads The lead is placed in the holder, and dressed by rubbing the end against abrasive
20、 paper. With the pencil held perpendicular to the abrasive paper, the end of the lead is abraded until it is flat and free from chips or nicks. 5.4 Procedure The test procedure is as follows: (a)Allow the dressed lead to protrude 6 1 mm from the mechanical holder (see Figure 1). (b)Ensure that the s
21、urface temperature of the coating does not exceed 40C. (c)Hold the pencil at a writing angle of 45 to the paint surface and push forward, away from the operator (see Figure 2), along the surface a distance of 6 mm to 10 mm, using as much downward force on the pencil as will either cut the paint film
22、 or cause the tip of the lead to crumble. (d)Make successive trials beginning with the softest lead and continuing with progressively harder ones until the appropriate lead that will cut or scratch the film is found. (e)Using normal vision, carry out a minimum of three series of tests. A fresh edge
23、of lead is required for each test. Either rotate the pencil to present a fresh edge, or redress the lead and adjust the protrusion to 6 1 mm. (f)Note the hardness of the hardest lead that will not cut or scratch the coating. (g)Consult the limits recommended by the coating manufacturer and determine
24、 the extent of cure. DIMENSIONS IN MILLIMETRES FIGURE 1 CLUTCH-TYPE PENCIL FIGURE 2 POSITION OF LEAD DURING TEST Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 .au Standards Australia 5 5.5 Report The test report, if required, shall include the following: (a)Product identific
25、ation type and batch. (b)Method of application of paint, curing conditions, and film thickness. (c)Details of substrate and coating system. (d)Grade and make of leads. (e)The hardest lead that will not disturb the coating. (f)Whether the coating was considered cured. (g)Report number and date of tes
26、t. (h)Name of the testing authority. (i)Reference to this Australian/New Zealand Standard, i.e. AS/NZS 3894.4, Method A. (j)Any deviations from this test method. 6 METHOD BDUROTEST STYLUS 6.1 Principle A hand-held, adjustable, spring-loaded scriber or stylus is applied at a constant pressure while i
27、t is drawn across a coating surface. Starting with the softest spring setting, the test is repeated with the spring tension progressively increased until the coating is cut or scratched. 6.2 ApparatusStylus A spring-loaded stylus held in a pencil-like device, utilizing a range of at least three spri
28、ngs. Table 2 indicates the spring range normally applicable to each type of coating. TABLE 2 SPRING RANGE FOR DUROTEST STYLUS Spring identificationRange *Coating type Plain Red Blue 0300 01 000 02 000 Alkyds, chlorinated rubber, vinyl Epoxy polyurethane, AS/NZS 3750.15 Type 4 zinc silicate AS/NZS 37
29、50.15 Type 1, 2, 3 zinc silicate *The limit of the reading varies within a generic coating range. The required full-cure readings may be obtained from the coating manufacturer. 6.3 Procedure The procedure is as follows: (a)Fit the stylus with the plain spring (i.e., the softest of the three springs)
30、. (b)Ensure that the surface temperature of the coating does not exceed 40C. (c)With a set tension, hold the stylus perpendicular to the coating surface and draw it towards the operator. (d)Employing normal vision, inspect the coating for cutting or scratching by the stylus. (e)If there is no damage
31、, repeat Steps (b) and (c) with progressively higher tension settings and, where necessary, with the next stiffer spring fitted to the stylus, until the coating is damaged. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 Standards A.au 6 (f)Read the hardness from the scale cor
32、responding to the first appearance of cutting or scratching of the coating, e.g. R400, corresponding to a red spring setting of 400. (g)Consult the limits recommended by the coating manufacturer and determine the extent of cure. 6.4 Report The test report, if required, shall include the following: (
33、a)Product identification type and batch. (b)Method of application of paint, curing conditions, and film thickness. (c)Details of substrate and coating system. (d)The hardest spring and tension reading that will just damage the coating, e.g. R400. (e)Whether the coating was considered cured. (f)Repor
34、t number and date of test. (g)Name of the testing authority. (h)Reference to this Australian/New Zealand Standard, i.e. AS/NZS 3894.4, Method B. (i)Any deviations from this test method. 7 METHOD CRUB TEST 7.1 Principle The surface of the coating is rubbed with a cloth saturated with a solvent suitab
35、le for the coating being tested. Fully cured coatings will not be significantly affected by the solvent whereas under-cured or partially cured coatings will have a tendency to dissolve. The cloth and coating surface are inspected for discolouration, change of gloss, film thickness loss, exposure of
36、the underlying film or the metal substrate. 7.2 Apparatus and materials 7.2.1 Cotton cloth Clean material that is not affected by the solvent, and of a colour contrasting with that of the coating being tested. NOTE: Clean cotton material is used to give consistent results. 7.2.2 Solvent Methyl ethyl
37、 ketone (MEK), or mineral turpentine for alkyd coatings, or other solvents advised by the coating manufacturer. NOTE: When using solvents, occupational health and safety legislation is to be observed. 7.3 Procedure The procedure is as follows: (a)Clean all chalking and contamination from the test su
38、rface. (b)Ensure that the surface temperature of the coating does not exceed 40C. (c)Saturate the cloth with the solvent, so that it drips from the material. (d)Rub the test surface with the saturated cloth and the middle and index fingers using 10 double strokes (i.e., 10 complete oscillations), ap
39、plying a moderate force not greater than 2 kg. (e)Allow the surface to dry and recover for 5 min. (f)Examine the cloth for deposits or discolouration and note the appearance of the surfaces and any loss of coating. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 .au Standards
40、Australia 7 (g)Select an adjacent area to be used as a reference. Repeat Steps (c) through (e) using a water-dampened cloth. Note the effect of rubbing without the influence of solvent. (h)Consult the recommendations of the coating manufacturer and determine the extent of cure. NOTES: 1An unmodified
41、 chemically cured coating, such as epoxy or polyurethane that is fully cured, should be unaffected with no loss of dry film thickness and no deposit on the cloth. After the recovery period, there may be a slight change in gloss without significant softening of the surface. 2Some modified chemically
42、cured two-pack coatings may soften but will eventually recover to normal hardness with a slight trace of colour on the cloth. 3ASTM 4752 provides a rub test for ethyl silicate zinc-rich primers. 7.4 Report The test report, if required, shall include the following: (a)Product identification type and
43、batch. (b)Method of application of paint, curing conditions, and film thickness. (c)Details of substrate and coating system. (d)The solvent used for the test. (e)Whether the coating was considered cured. (f)Report number and date of test. (g)Name of the testing authority. (h)Reference to this Austra
44、lian/New Zealand Standard, i.e. AS/NZS 3894.4, Method C. (i)Any deviations from this test method. 8 METHOD DBARCOL HARDNESS IMPRESSOR 8.1 Principle A hand-operated, model 935 Barcol impressor is used to obtain an indentation reading on the coating surface. The reading obtained will indicate the degr
45、ee of cure associated with the coating material. NOTE: The test method, using the model 934 Barcol impressor described in ASTM D 2583, is applicable to rigid plastics and is not suitable for assessing partly cured materials or soft plastics. 8.2 Apparatus 8.2.1 Indentor A model 935 Barcol impressor,
46、 consisting of an indentor with an indicating dial (see Figure 3). 8.2.2 Calibration standards Discs supplied by the manufacturer of the instrument to allow calibration. 8.3 Procedure The test procedure is as follows: (a)Calibrate the instrument in accordance with the instrument manufacturers instru
47、ctions. (b)Ensure that the surface temperature of the coating does not exceed 40C. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 20 May 2008 AS 3894.42002 Standards A.au 8 (c)Place the impressor on the test surface. Set the point sleeve to the top of the coating. Set the legs on the coating so that t
48、he indentor is perpendicular to the surface being tested. (d)Grasp the case of the instrument firmly between its legs and the point sleeve. Apply quickly, by hand, a uniformly increasing force on the case until the dial indication reaches a maximum reading. Immediately note the dial reading at the i
49、nstant of needle deflection. NOTE: The reading will decrease with time due to creep. (e)Check the indentor reading obtained against the required cure figures supplied by the coating manufacturer. 8.4 Report The test report, if required, shall include the following: (a)Product identification type and batch. (b)Method of application of paint, curing conditions,