Dust and dirt can actually cut fibers as they expand and contract with changes in temperature and humidity.
Provided that there is no active damage (holes, rips or frayed seams), delicate fabrics or embellishments (as in a crazy quilt), simply airing the quilt outside on a nice summer day will remove dust and freshen the quilt.
You could also try vacuuming it with the brush attachment of a low powered vacuum cleaner.
If you are cleaning a quilt with elaborate embellishments, or one with damage, put a clean, fine mesh screen over your quilt first. Clothing is actually put into a big washing machine and washed with chemicals instead of water.
If you plan to display your quilt on a bed or on a wall, you may wish to consider wet washing it. A simple vacuuming is often the best choice for quilts which cannot be wet washed.
If you decide to wash your quilt, be aware that you may permanently damage your quilt no matter how careful you are!
It seems like forever you have been searching for that perfect antique quilt. It spoke to you in sweet, melodious tones at a garage sale or auction.
It smells a little, and has some odd spots, but what the heck? Are you going to display it folded, hung on wall, or on a bed?
The colors are wonderful the quilting sublime, the price exactly right. If you are going to display the quilt folded over a rack, it may not be necessary to clean it at all.
It's always best not to subject an antique textile to any stress, but it is not a good idea to leave a quilt dirty, either.
You may wish to seek the advice of a professional textile conservationist first.
The American Institute for Conservation, 1717 K St.
NW, Suite 200, Washington DC 20006 can give you a list of professional conservators in your area. Wet washing a quilt may cause those dyes to run, change color or disappear altogether.