To make the best and most durable quilts, 100% cotton is the best. Synthetic fabrics aren't good in quilts because, as they are generally stronger than natural fabrics made of cotton, they can cut into the cotton material in the patches, causing disintegration of the quilt. Even thread should be 100% cotton.

Because fabric and thread for quilts is somewhat specialized, it would be best to shop at a quilting store. A quilting store is staffed by people who are familiar with quilt making and what is required for making a quilt. Some quilt shops also carry sewing and quilting machines, as well as giving lessons in quilting. Shopping at a fabric store is possible and may be less expensive, but this is one time you "get what you pay for." Cheaper fabric is usually not strong enough to stand up to repeated use and washing. When you put many hours of your time into designing and creating a quilt, you definitely want it to last.

Look carefully at the fabric and make sure that the threads, vertical and horizontal, are at a right angle to each other. Don't buy fabric that seems to pull one direction or another, or has a pattern that is not in line with the threads. Thread count is how many threads are in a square inch. Most quilters prefer between 60-80 threads per square inch for durable fabric. Make sure that the color on the fabric does not rub off.

You'll want to wash the fabric first to remove sizing, but it will also show you how the quilt will wash if you use that fabric. If it does not wash well, the best suggestion is to toss it out and find a new fabric.