I bought a couple of flannel "baby blankets" at a thrift store a few years ago. They only measured about .012" in thickness. But they make nice cleaning patches, and; they work okay as ball patches in the smoothbore.
Back to pillow ticking. I've used a lot of it for shooting patches and like it pretty well. But for a good while I've bought mattress ticking, which I like better. After washing, pillow ticking measures .015" but mattress ticking measures .020". I also like denim, .024" and cotton canvas duck at .022". The thicker materials work best for me although denim can be a struggle to seat in some guns.