Shadow Silk

Shadow Silk is dark smoky-colored silk spun by spiders. It is often used in Tailoring patterns.

Source
Shadow Silk drops off Spiders in Blackrock Spire, Dustwallow Marsh, the Eastern Plaguelands, Searing Gorge, Silithus, Stratholme, Swamp of Sorrows, The Hinterlands, and the Western Plaguelands.

Engineering
Gnomish Net-o-Matic Projector
 * Parachute Cloak

Tailoring

 * Shadoweave Boots
 * Shadoweave Gloves
 * Shadoweave Mask
 * Shadoweave Pants
 * Shadoweave Robe
 * Shadoweave Shoulders

Leatherworking

 * Shadowskin Gloves