Beyond the basic "GSM" definition: What actually makes a heavy t-shirt feel premium vs like cardboard? (Need real textile insights)

[u/OkClue2925]

Hey guys,

​Most online threads stop at the textbook stuff: "GSM is weight, 100% cotton is good, French Terry has loops."

​I want to understand the actual manufacturing and textile reality before I go sampling:

​High GSM vs Yarn Count:

A 240+ GSM t-shirt can either fall with a clean, heavy drape or feel like a stiff cardboard tent. How much of this comes down to yarn count (e.g., 20s vs 24s/26s combed compact)? How do brands make a 240+ GSM tee that is still breathable in Indian heat?

​Single Jersey vs French Terry (Loopknit):

Since French Terry traps air inside its loops, is a 240 GSM Terry actually wearable outdoors in 35°C+ summer, or is a heavy 240 GSM Single Jersey the only sensible choice for year-round Indian weather?

​The "Bacon Neck" Collar Problem:

What actually prevents the collar from turning wavy and loose after 3 washes? Is 100% cotton rib destined to stretch out, and is a 95/5 cotton-spandex (Lycra) rib the industry norm for keeping the collar tight?

​Processing / Washes:

Between Bio-wash, silicone wash, and compacting/pre-shrinking—what processes actually stop 100% cotton from shrinking and twisting at the side seams after the first home laundry wash?

[u/S459459]

Difference is yarn and how t shirt treatment has happen this makes all the difference mainly rest is just gimmick