ISO 23169:2020 pdf free.Paints and varnishes – On-site test methods on quality assessment for
interior wall coatings.
5 On-site cleanability (stain removal) test
5.1 Principle
The standardized stains are applied on interior wall coatings and dried for 10 mm. Then the cleanability test is run with the specified test apparatus (wet-scrub tester). The tristimulus value of the coating is measured before and after exposure.
5.2 Apparatus
5.2.1 Wet-scrub tester.
The scrub testing machine is operated manually upwards and downwards with a stroke length of (180 ± 10) mm and operating at approximately (20 ± 1) scrub cycles per minute. The number of scrub cycles is recorded manually. Do not mix up the stroke length with the scrub length.
The apparatus for determination of cleanability and wet-scrub resistance of interior wall coatings is shown in Figure 2. The apparatus can give consistent pressure and contact area when running the test through the below designs. Three wheels are used to control the track when running the test. The height of the wheel is designed to be lower than the height of sponge plus the black cloth, to ensure certain deformation and to provide a certain friction.
NOTE The force provided by the deformation of sponge has been determined by dynamic mechanical analysis (DMA) to be (2,6 ± 0,2) N.
A sponge height of 15 mm is recommended to deliver the reasonable result. The contact area which is set by the location of the wheels is about 60 mm x 35 mm. The sponge (cleanability test) or the sponge covered by the black cloth (wet-scrub resistance test) is fixed by one balance bolt with two screws on each side. When the sponge is used under the black cloth, the purpose is to provide some damping when rubbing, not to bring extra damage to the coating due to the hardness of the main material. When determining “cleanability”, the black cloth does not need to be used; when determining “wet-scrub resistance”, the black cloth needs to be used.
5.3.2.2 Alcohol soluble black solution
Put water in accordance with grade 3 of Iso 3696, into a vessel, then add ethanol (CAS-No 64-17-5, analytical reagent grade) and mix thoroughly. Then add the alcohol soluble black (solvent black 7, CASNo 8005-02-5) at a mass ratio of water: ethanol : solvent black 7 63:27:10 and mix thoroughly. Prepare this solution 24 h in advance before test. Its shelf life is 7 days.
NOTE For specific needs, other soiling agents such as vinegar, black tea, blue ink, can also be used. See Annex A.
5.4 Procedure
5.4.1 Division of test area
Select two vertical wall areas for the test. Each area shall be larger than 200 mm x 300 mm. Apply two 90 mm stripes of adhesive tape (5.2.4) with the size of 90 mm x 20 mm horizontally on each area on the wall as spacers (see Figure 3). One soiling agent is tested on one test area with three test strips, two soiling agents are chosen in the procedure. If more soiling agents are to be tested, then the number of test areas shall be increased accordingly. Tested area is in the middle of the selected area.
5.4.2 Determination of the initial tristimulus value of the untreated coating
Measure with the spectrophotometer (5.2.2) the tristimulus value Y10 (as described in the colour space of CIE 1964) of the coating in each uncoated test stripe Y10,u before the gauze is applied.
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