...some manufacturers add a mercherised finish to their fabric to give it a smooth silky finish, mostly it will wash out...its the same process added to make chintz shiny and will wash out...the fabric of 1 or 2 decades ago didnt have all these processes, sewers were too in love with synthetics back then and didnt want cotton feeling smooth and silky...
...these days there are many more manufacturers of patchwork fabric so competition means theyre all looking for an edge...having been a sewer for over 30yrs and worked in the industry, i personally wont touch any patchwork fabric which has been through multiple processes and treatments because 99% of the time theyre covering an inferior quality fabric...a good quality fabric should have substance, a firm hand and an even, dense weave - hold it up to the light with your hand held about 6" behind it, you should be able to see a blurry shadow of your hand with smudgy outlines, not a clear outline...you shouldnt ever be able to see between the weave...