Don't you just hate all the strings that come loose during the prewashing of quilting fabrics?
The threads twist and pull at the fabric when they get tangled up in the wash, and you have to remove them before they go into the dryer so that fabrics come out wrinkle-free. Neglect to remove the threads and you'll see oodles of accordion pleats when you take fabrics out of the dryer; folds that aren't always easy to press flat.
It's easy to eliminate nearly all of the strings. Just clip off a little triangular section from each corner of fabrics before you wash them. Try about 1/2" or a little less. You'll still see a bit of fraying, but not enough to create bunches of knots.
Give it a try the next time you prewash your quilting fabrics -- the little snip really makes a difference.
Most experts recommended cool water washing, low dryer temperature and gentle or delicate cycles.
Some manufacturers go so far as to recommend no heat, no ironing, no drying.
Most of our fabrics are 100% cotton and cotton is notorious for shrinking.
Expect to see about a 1/4-1/2 inch shrinkage on a full yard of fabric.
If you don't want to prewash your fabric but are concerned about shrinkage, you could try cutting a 3×3" square, wash and dry it, and then measure to see if has shrunk.
Washing Cotton Fabrics:
Sort your fabrics to be washed into lights and darks.
Set your washing machine temperature to cold.
Fill with water to the desired level and add your soap. Prewash quilt fabric with a neutral soap like Orvus (you'll often find it as 'Quilt Soap' at the quilt store) If you do not have Orvus, it is OK to use your regular laundry soap, but do try to avoid the optical brighteners.
Agitate to mix the soap evenly through the machine. Turn off the machine.
Open your quilt fabrics (this helps to prevent setting the fold) and distribute them evenly throughout the washing machine. Turn on the machine and complete the washing cycle.
To dry your quilt fabric tumble dry on low removing the fabric from the dryer while it is still slightly damp. You can skip the dryer altogether by either line drying or laying your quilt fabric out flat to dry.
If you will be using your fabric immediately, then iron. If these fabrics are going straight to your stash, just fold neatly for now. Remember to press before you use them. Pressing only once saves time. The trick is to lay the slightly damp fabrics, fresh from the dryer, flat immediately to avoid setting in wrinkles.
Vinegar in the water helps to hold the color in.
You should always use an unscented, liquid based, color-free detergent to wash your quilt fabric
Refrain from using any detergent that contains a fabric softener. Fabric softeners and the scents and dyes in regular detergents can damage the fibres in the fabric and so should be avoided.