Charles Ellicott Commentary Leviticus 13:58

"And the garment, either the warp, or the woof, or whatsoever thing of skin it be, which thou shalt wash, if the plague be departed from them, then it shall be washed the second time, and shall be clean." — Leviticus 13:58 (ASV)

And the garment ... — According to Leviticus 13:54; Leviticus 13:56, the suspicious symptoms often disappeared after the fabrics had been washed and put in quarantine for a week, thus showing that it was not real leprosy. But though non-leprous, the garments had to be washed a second time before they could be pronounced fit for use.