Unfortunately, the fact that I travel a lot and always bring some stuff with me - in particular when traveling with low cost airlines, which means that the backpack must contain all I need for some days - means the backpack is often crammed full, and has to bear a lot of mechanical stress. In particular, when it's very very full, the most stressed part is the closing zip. Now, zippers are often a weak point in any kind of bag/clothing/anything, for two main reasons:
1) they can break
2) the fabric they are attached to can break.
This instructable (my first!) is about fixing the second case. I think you can apply the idea to many other kinds of objects, such as purses, tents, maybe also some kinds of jackets (though I wouldn't recommend this for regular clothes!). It doesn't require any particular ability in sewing - I certainly don't have any! - and you can get the material for a couple of €, and apply it in 10-20 minutes.
If you find this method useful, you can vote for this instructable in the "fix it" contest.
Step 1: What NOT to Do
This was not a good idea. Exactly as had already happened before, the fabric started to tear apart again in a matter of hours, and in this process I had lost a couple of precious millimiters of tissue!
So the two main lessons to be taken from this failed attempt are
1) don't simply try to sew back the teared fabric together, because it's going to get worse, but rather do as I suggest in the next steps,
2) most importantly, act as soon as possible, when you notice even a minimal damage in the fabric.
Step 2: What to Do - What You Will Need
1) sewing kit: you need needles and thread, and a thimble (not pictured) can also be very useful
2) the crucial ingredient: "power tape". I don't know if this is/has a technical name, but the fundamental feature is that it must have a weave of some kind of thread inside - you can see it in the second picture,
3) scissors - the packaging of my tape suggests you can tear pieces by hand, but in fact having a good pair of scissors allows for much more precision.
Step 3: Apply the Tape
On the other hand, even the strongest sewing thread will not do, because the fabric itself will tear apart the more you sew on it.
But if you use the reinforced tape and sew it to the fabric, then it will at the same time keep the two pieces together and make the fabric itself much stronger.
The first step is to cut away pieces of threads which were torn away from the fabric - but without exaggerating: if in some place the fabric is simply weakened/distorted, but it still has some woven structure, it can still be useful, so don't cut it away.
Then, apply the tape on both sides of the seam (notice that at that place, the two pieces of fabric are parallel, with the free extremity on the same side. Cut the tape in half if it is too large (it was, in my case), and stick it so that it covers all the part you want to sew and even more toward the zipper/body of the backpack, but is not redundant on the free side of the fabric (in particular, where it bends the tape should attach as much as possible to the fabric, not stick to itself).
You must cover with tape all the damaged area, and at least a couple of centimeters more on each side.
Step 4: Sew
- I always used a double thread, so that it is stronger: I just folded it in half and started sewing: you may want to consider using a much stronger thread than the one you find in a basic sewing kit (though I don't think the fragility of the thread is the critical point here), but still, working with double thread is also more comfortable, because there is less risk that the free ending exits from the needle hole,
- try to juxtapose the two parts of fabric as they were originally, but sew a bit nearer to the zipper than the previous stitching,
- since the fabric is quite thick, this is where a thimble can turn out to be very useful,
- begin to "come back" with your stitching before you have used half of your thread, otherwise making the closing knot becomes very annoying: if you didn't cover all the area, you can then just continue with a new piece of thread,
- before making the final knot, pull the thread so that it is tight, and any redundant millimeter of thread is taken away from the stitches,
- I used an ugly colour (well, at least for this backpack) and my stitches are not very regular, but I didn't care too much, since this part will anyway not be visible - it is inside (in fact, I just chose a thread which would stand out in the pictures, and which I would hardly need for fixing clothes...).
For an even better result, you may want to sew two parallel stitchings, one nearer to the original one, and one even nearer to the zipper. But try to figure out before if this will hinder the opening/closing of the zipper (it won't if, as in my case, the fabric is flexible enough).
Step 5: Cosmetic Touches
That's all: while the first fix, without the tape, had lasted 1-2 days, now it's been 20 days ago since I took those pictures, 20 days of very intensive use of the backpack, and the stitching shows no sign of usury.
If this instructable helps you save your beloved backpack/purse/tent, please vote for me in the "Fix it" contest!