Is Percale cotton?
No. It is a type of weaving process sometimes referred to as Percale Cotton. It can be 100% cotton but it can also be other types of thread, for example: cotton and polyester blend, or cotton and linen, etc.
Then what is it?
It's the superior quality of the weave-type that is the defining factor of Percale. The distinctive single pick insertion is made from both carded and combed yarns. Carded is less expensive but when combed the short fibers are removed making it smooth, compact, and better suited for weaving. Most sheets start with thread counts of around 200.
What is Insertion?
Insertion means that when fabric is woven, vertical yarns are inserted by horizontal ones. When horizontal yarns are inserted one yarn at time, that is single pick insertion, and four yarns at a time is a 4-pick insertion. Higher insertions make for a faster weaving process which sacrifices a bit of quality. But that can be countered with a slightly higher thread count.
What are the Advantages?
Percale sheets are crisp, firm, and smooth. They are a medium weight, wash well, and are very affordable. The tightly woven yarns are excellent for waterbed sheets and they are even more comfortable with laundering. In many ways a 400 thread count sheet is better than a non-Percale 600 thread count with 4 pick insertions.
Whether labeled "Percale Cotton" or Percale Sheets, note the blend, thread count and price. Chances are Percale will please you.