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ASTM D4576-16(R2021) pdf free download

ASTM D4576-16(R2021) pdf free download.Standard Test Method for Mold Growth Resistance of Wet Blue and Wet White
1. Scope
1.1 This test method covers the determination of mold growth resistance ofWet Blue and WetWhite subject to storage and shipping requirements and intended for use in leather manufacturing. This test method may not be suitable to evaluate fungicides that are inactivated by proteins. This includes alkyldimethylbenzyl ammonium chlorides. 1.2 Conclusions about mold growth resistance are drawn from the results by comparing the test with a simultaneously run control of known resistance. Success or failure is deter- mined by the amount of mold growth relative to the control. 1.3 To allow use of this test method by any laboratory, flexibility has been permitted in times, temperature, and humidity of incubation, inoculum, hide sampling area, and choice of control. These may be adjusted to fit local conditions but must be standardized. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Summary of Test Method
3.1 Wet Blue and Wet White test specimens are surrounded by but not covered with agar, inoculated, and incubated. 3.2 After various incubation periods, mold growth is rated as a percentage ofthe Wet Blue and Wet White surface covered by mold. 3.3 Resistance to mold growth ofthe Wet Blue or Wet White test specimen is determined by comparison with Wet Blue or Wet White of known resistance characteristics (the control), that is tested simultaneously.
4. Significance and Use
4.1 This test method provides a technique for evaluating mold growth resistance characteristics of Wet Blue and Wet White, and should assist in the prediction of storage time before molding occurs. 4.2 The degree ofcorrelation between this test and commer- cial quantities of Wet Blue and Wet White in storage or shipment situations, or both, has not been fully determined.
5. Interferences
5.1 A common interference is contamination of plates, agar, or samples by unwanted organisms that settle in from the environment. 5.2 Volatility and Leachability of Biocides—A “zone of inhibition” where no mold grows on the agar adjacent to the specimen indicates that the fungicide may leach.
6. Apparatus
6.1 Petri Dishes, 120 mm diameter. Sterile plastic dispos- able dishes are preferred. 6.2 Incubator, or location providing similar conditions be- ing free of drafts, and capable of a constant (62 °C) tempera- ture within the 26 to 30 °C range. 6.3 Medicine droppers, disposable plastic type delivering 30 to 35 drops per mL.
8. Sampling, Test Specimen, and Test Units
8.1 Take test specimens from equivalent hide locations (for example, butt area) for both test and control. 8.2 If unable to test immediately, hold test specimens in separate plastic bags and keep cool. 8.3 Test specimens should be a square, with a side of 25.4 mm (1 in.). 8.4 Use three test specimens for each test unit of Wet Blue or Wet White surface to be evaluated.
9. Procedure
9.1 Agar Preparation: 9.1.1 Agar Requirements—A split Wet Blue or Wet White test specimen requires about 25 mL solution and an unsplit Wet Blue or Wet White test specimen requires about 40 mL. Calculate number of millilitres of agar required for tests to be performed, allowing 50 mL for vitality check. 9.1.2 Weigh out 3.9 g potato dextrose agar for every 100 mL of agar required. 9.1.3 Pour a volume of water equivalent to total millilitres of agar solution to beaker. Bring water to boiling on hot plate equipped with magnetic stirrer mechanism. While stirring, slowly add dry agar. 9.1.4 Boil agar for 20 min. N OTE 1—Pressure cooking for 20 min. is preferable to open boiling. 9.1.5 Cover with aluminum foil to prevent contamination and cool to 50 °C before pouring. N OTE 2—This temperature is critical, as 50 °C allows some water of condensation to develop on petri dish cover providing humidity for growth of fungus. 9.2 Agar Plate Preparation: 9.2.1 Place one Wet Blue and Wet White test specimen in center ofeach petri dish with the surface to be tested facing up. 9.2.2 Carefully lift cover from each dish and pour agar just up to, but not over, the top surface of the test specimen. 9.2.3 Prepare one dish with agar only (without Wet Blue) for evaluation of the vitality of the inoculum. 9.2.4 Let agar solidify for about 20 min.

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