If they are long drapes, I have just used a sheet. They work great. Also the muslin comes in a wide width that is very easy to use. It is really what look you want..

Susie

I use muslin quite frequently to line drapes where room darkening isn't a requirement. It is relatively inexpensive and holds up quite well.

Thanks guys...do you find that muslin (or a bed sheet) protects the face material from sun damage?

Both works well. Be sure to buy a good guality muslin. If you don't want a seam, buy the extra wide muslin that they use for quilts..

I've used muslin behind curtains on a boat which was constantly in the tropical sun and they lasted for years without fading. It was a dark blue Hawaiian print fabric which would have faded if it hadn't been lined so as far as I know, muslin works fine to keep fabrics from fading.

thanks everyone...that's exactly the info I needed. Is there an inexpensive website that you guys buy from?

Joann fabrics runs sales frequently. Check out their web site for a coupon for in store purchases. I worked for Joann for several years I don't buy their garment fabrics or calicos but do buy their muslin and interfacings when they are 50%off.