Silk was a woven material. According to Tegan Jovanka, it was made from the spit of silkworms. (PROSE: The Immortals)
During his visit to Venus, the First Doctor had two bright red silk handkerchiefs in his pockets. (PROSE: Venusian Lullaby)
In the 11th century, U'thai's warriors wore silk shirts which allowed them to remove arrows effortlessly. (PROSE: The Immortals)
In the 12th century, silks were among the goods sold by Ben Daheer. (TV: The Crusade)
In the 17th century, silks were among the goods smuggled by Edwards' men. (TV: The Smugglers)
Sarah Jane Smith wore a silk scarf. (AUDIO: The Paradise of Death)
On Kirith, Ace was given a silk dressing gown. (PROSE: Timewyrm: Apocalypse)
Iris Wildthyme wore a silk dressing gown one morning inside her Celestial Omnibus. (PROSE: Iris Wildthyme and the Unholy Ghost)