Four Items to Launder Separately
New clothes: “Few things are more exciting than adding new clothes to your closet – but make sure they’re washed separately on their first few washes.” New garments are more likely to bleed color and shrink, and washing them separately, according to label instructions, reduces those risks.
Denim: You know to wash dark clothes separately from lights, but be especially careful with denim because it sheds dye for many cycles. Besides, jean zippers can damage delicate fabrics, especially knits.
Lint-shedding items: Clothing that’s likely to shed link should be washed inside out on a cold gentle cycle. Avoid combining such garments with fabrics the lint will stick to, such as microfiber.
Very soiled clothes: Pamper extra-dirty clothes by pre-treating stains and washing them alone using a longer cycle. This will clean them well and avoid transferring dirt.
Source: MarthaStewart.com