Ideal temperature for washing dark clothes to prevent fading | Popgen Tech
If you wash dark clothes in hot water, you need to cool the jets; hot water is notorious for causing dye to run. Washing in water that is too hot will cause your dark clothes to fade quickly, and the dye may run onto the lighter colored items in the mix and stain them. Professional cleaners at The Maids explain that hot water molecules move faster than cold water molecules, rubbing into the fabric and causing the fibers to open up. This is great for removing dirt and stains from lighter colored clothes, but the exposed fibers can also release dye molecules from darker clothes.
When it comes to washing dark laundry, you want to use cool water, around 60 to 80 degrees Fahrenheit (via Wash Laundry). Turning the garment inside out and using a mild, color-safe detergent will also help preserve the color. If your dark clothes are new, it’s always best to wash them several times separately before throwing them away with your other items. You can also find laundry detergents and additives specially formulated for dark clothes. After a thorough comparison, Home Cleaning Planet recommends Woolite Dark Defense and OxiClean Dark Protect Laundry Booster.