Percale versus Muslin
Better quality muslin cloth starts at around 140 thread per square inch. Higher quality muslin starts at 180 or so threads per square inch, with percale being anything at or over 200 threads per square inch.
Muslin bed linen for ages was standard choice for economical housewives and those charged with housekeeping for everything from hotels to hospitals.
Muslin is made from thicker cotton threads thus produces a heavier final product. All that weight and thicker threads also meant muslin bed linen weighed more which was a big factor when it came to laundering.
Laundries either charge by piece or weight, with most industrial/commercial laundries using the latter. So a home or other establishment that sent their washing out suffered higher costs with muslin bed linen because it weighed more.
Also muslin being made from thicker threads absorbs and holds lots of water. This meant drying took longer (machine or air), and ironing (by machine or hand) also was more of a chore..
Muslin being more hard wearing than percale isn't always true either. Because the latter not only has more threads per square inch, but they are thinner as well you get a much tighter and stronger weave.
Percale...
Muslin had a reputation (at least in lower grades) of being economy to downright poverty choice for bed linen. Percale OTOH was seen as more upscale. Wamsutta shook up that notion.
About 1936 Wamsutta Mills came out with "Eco-Tension" weaving of their percale fabric. This was touted to produce a stronger, high quality, luxrious and hard wearing percale fabric. Named "Supercale" Wamsutta launched a PR and marketing blitz starting in late 1930's to get housewives and others to upgrade from muslin to "Supercale".
Main talking points for Supercale was that percale bed linens were lighter and thus saved money if sent out to laundries. This and or they were also far easier to launder at home (including ironing) again due to their lighter weight compared to muslin. None of this sacrificed durability and long wear, with Wamsutta (and soon other mills) all saying that their percale bed linens gave just as good or longer wear than muslin.
Look through these old adverts for Wamsutta Supercale. Copy always keeps to few key themes; economical to own, easy to launder, serviceable with long wear, and of course luxurious to sleep upon.
https://www.tias.com/wamsutta-supercale-sheets-ad---may-1939-581656.html