My son is a Boy Scout and had a very nice and somewhat expensive cold-weather sleeping bag from The North Face. He recently discovered a small tear in the nylon fabric. I am looking for advice about how to patch it. Can you give some advice to a Loyal Scout Mom?
Yeah, I think we can make some progress, Jodi. Perhaps the easiest thing to do is make a repair yourself with one of several patch materials out there. One good choice is Gear Aid's Tenacious Tape ($4.50). It's a tough but lightweight material with a super-sticky adhesive backing that can fix holes and tears in nearly any material. It comes in a variety of colors, so you probably can match the bag's color pretty closely. Or, use the clear version, which has a low-shine finish so it blends nicely into the existing color. Tenacious Tape is flexible, so can take the abuse of being stuffed into a stuff sack. And it will ensure that the tear won't spread.
You also could ship the bag to a repair facility. For a bit more money, they could do a repair to restore the bag to like-new condition. I've long used Rainy Pass Repair, based near me in Seattle. I've gotten stuff back from them in BETTER than new condition—the repair sometimes cures a design flaw in the original item. Not really the case here, but they can sure fix the problem. You can e-mail them and get a rough estimate (maybe send a picture of the tear) of the repair cost. Then ship the bag to them and you'll have it back in probably two weeks.
Of course, there's always duct tape!