I'm looking for new king-size sheets for my new bed and I'm not having much luck... Seems like every time I get cotton sheets, all I can find are these linty, wrinkly, rough ones, regardless of the thread count. Now, I know when I was younger my mom would pick up vintage bed sheets from flea markets and they were always super smooth and cool to the touch (not to mention super durable - I have a mint green pillow case from the '70s that I still use today!)
So doing some internet sleuthing, I stumbled upon an Amazon.com review where a person who's had the same experience as me explains that those old sheets owe their silkiness to an industrial process called mercerization. Take it away, Wikipedia:
Mercerisation is a treatment for cotton fabric and thread that gives fabric a lustrous appearance. [...]
The process was devised in 1844 by John Mercer of Great Harwood, Lancashire, England, who treated cotton fibres with sodium hydroxide. The treatment caused the fibres to swell, which in Mercer's version of the process shrank the overall fabric size and made it stronger and easier to dye. The process did not become popular, however, until H. A. Lowe improved it into its modern form in 1890. By holding the cotton during treatment to prevent it from shrinking, Lowe found that the fibre gained a lustrous appearance.
Today the modern production method for mercerised cotton, also known as "pearl" or "pearle" cotton, gives cotton thread (or cotton-covered thread with a polyester core) a sodium hydroxide bath that is then neutralized with an acid bath. This treatment increases lustre, strength, affinity to dye, resistance to mildew, but also increases affinity to lint. Cotton with long staple fibre lengths responds best to mercerisation. Mercerised thread is commonly used to produce fine crochet.
The Amazon.com reviewer continues:
Sheets and pillowcases were marketed as mercerized and it was included on the label. Mercerization is a process of washing the fabric or thread under tension (to prevent shrinkage) with sodium hydroxide and an acid neutralizer which not only gives it a smooth luster and increases strength but reduces lint, improves mildew resistance and increases affinity for dye so it won't fade or bleed. In the 70's, we could buy sheets and pillowcases which were also "Pre-shrunk," "Cotton blend" and "no wrinkle, no iron."
You can still find vintage cotton/poly sheets in unopened, good condition on Ebay and Etsy. Hard to find, but totally worth the search!