SHANE STEINKAMP'S BACKPACKING BASE CAMP
ZIPPERS AND ZIPPER REPAIRLAWS OF ZIPPERS
1. A clean zipper is a happy zipper.
After high school I worked at Beehive Shoe & Luggage repair, and I learned to fix zippers. They became sort of a hobby of mine, and I can restitch and sometimes replace teeth rather than replacing a zipper. I still do the hard ones to make a few bucks on the side. (I'm saving to buy a new tent, since my wife won't tarp.) There are only four or five shops in the country that can do this. Fortuna's in DC is one of them. I've had lot's of experience with zippers, so here goes: There are several kinds of zippers:
Plastic Vislon (Individual teeth)
Plastic Coil (Teeth are a long coil stitched to the zipper tape.)
(There are lots more, but usually you don't see them too often.)
The best and most durable zippers are Plastic Coil. Metal is second. Avoid Vislon like the plague. If you crack a tooth on a Vislon zipper, it's trashed. Most gear is equipped with Coil zippers now, and these are the most durable and easiest to fix. There are several parts to a zipper: The Tape, the teeth, the slider, the pull, and on coil zippers, a tiny piece of tape that runs through the inside of the coil. Before you go on a hike, you should buy spare sliders for each size of zipper you have on your gear. Sometimes you can't find them individually, so go to a fabric shop, and buy the shortest zipper of that size that you can, and familiarize yourself with it. I recommend buying one, just so you can break it and fix it so that you know how when you have to.
The weakest part of any zipper is the slider. The sliders are all made out of either brass or pot metal. If you have a coil zipper, 99% of the time, it's going to be pot metal. Sliders can wear out, and if you get trash, dirt, sand, or your tent flap caught in one, the slider can expand - causing a failure. The first rule of zipper maintenance is to be careful. A zipper is designed to work easily. If you have to force it, something is wrong. Always make sure that flaps or strings do not get caught in the slider, and if they do, be careful in removing them. Lubricate all your zippers on a regular basis using soap or candle wax. I use candle wax and soften it with a hair dryer. Don't cake the zipper with wax, just use a little. Barring this, if you slide the slider, and the zipper comes apart behind it, try to adjust the slider. Zip the zipper all the way down and squeeze the back end of the slider with a pair of pliers. Do this gently, and only a little at a time. If you squeeze too much, the zipper will jam. Only squeeze the back end of the slider. Don't clamp down on the little finger that holds the pull, because it can break. Failing this, replace the slider.
If the zipper has a metal stop, remove it. If the end of the zipper tape is stitched into a seam, DO NOT CUT THE TAPE OR THE SEAM. This is important. The teeth of a coil zipper are stitched through the teeth and onto the tape. Use a razor knife to cut those stitches under the three or four teeth at the end of the zipper. Be very careful not to cut the tape. Using nail clippers or some suitable tool, cut the teeth at the point where they enter the seam. Sometimes you have to remove two or three teeth, but try not to. Work the old slider off, and the new slider on. Compare the sliders to make sure that they are the same type. A metal slider will not work on a coil zipper and vice versa. Once you have the new slider on, you can restitch the teeth, or simply whip stitch the very end of the zipper together. Alternatively, you can buy metal stops that work like a double staple that you can put through the zipper and crimp with pliers. Do not use regular staples. Stitching is best.
Sometimes the stitching holding the teeth on wear out. You can use a very fine needle and thread to restitch the teeth. Be very careful and eventually you can learn the knack. It isn't that easy, but not rocket science either. The worst case is when the teeth break or pull away from the tape and become extruded. Even this can usually be fixed, but it takes lots of practice and sometimes more tools than you'll have on the trail. (Like a heat gun. This is the kind of repair I showed everyone to do at a trade show all those years ago.) Let's say the zipper on your sleeping bag gets snagged and breaks in the middle. What are you going to do? Work the slider down to the end, or take it off and cut the teeth as described above and zip the zipper up to the break, and then work the slider so that it zips past the break - even though you won't be able to zip it back down. Now take a needle and thread and whip stitch around and around the break to hold the zipper closed at that point. Now you can zip it down half way, and back up again - which is invariably better than not being able to zip it at all.
Total zipper replacement is hard. Almost nobody likes to do the job. If you are poor (like me) and can't replace or afford to have somebody fix your gear, you can replace the zipper yourself. If you want to try it, go buy a zipper of the correct type and length. Remove the old zipper, or if you aren't' that brave, cut the tape at the seam. Using a staple gun, staple one side of the zipper into place. Now staple the other side. Zip the zipper up to make sure the ends meet, and redo the staple job until they do. Now, while sitting in front of the TV or listening to music or visiting with family, stitch it in by hand using small (not more than 1/4 inch) stitches. The best thing to do is pass your needle back through the original holes. Don't try to do it using a machine unless you are really good with the machine. I am really good with machines, and I still do leather jacket zippers by hand, because it's easier to hit the same holes. Anyway, I hope this helps. If anyone has questions, I'll try to answer. Good luck on the trail, and take care of your zippers!