求翻译：1．用濃度為3%的鹽水潤濕棉布，用沾濕的棉布包住扣子﹐膠袋密封后室溫下放置24小時；看鍍層有無鏽蝕﹐發黑﹐發紅﹐發黃等異常現象；是什么意思？

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a concentration of 3 per cent of the saline moist cotton cloth, soaked with the cotton encase button, the plastic bags sealed 后 at room temperature placed 24 hours; see coated with no rusty, dark, flush, Wong anomalies,;

1. uses the density is 3% salt water moist cotton fabric, after the cotton fabric which gets wet wraps up the knot ﹐ plastic bag seal under the room temperature to lay aside for 24 hours; Looked whether there is coats rusts away ﹐ becomes dark ﹐ blushes ﹐ turns yellow and so on the abnormal phenomen

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