Tutorial: Zip Fly

Howdy-howdy stitchers! You know, jean-making seems to intimidate a lot of sewists; and while I don’t mind the compliments when people discover I make my own, I’m here to demystify the process. The truth is, jeans aren’t that difficult to construct. I think even a committed beginner could make them. And hey – jeans always look gooooood!

A fly front can seem complicated, but after you’ve made a couple and understand the general principles, they become really fun!

And before we start, I’m going to be emphatic – a solid 90% of the construction here was derived from Kenneth D. King’s “Jean-ius” class on Craftsy. Stop reading my tutorials and take his class. Ha! Just kidding. But – he is amazing.

Do you need special equipment to make a good-looking fly? No, you do not! Check out the fly in a handful of suits I made my son Nels a couple years ago – no serging, just pinking! If you use a metal zipper, you may need tools to remove the teeth: simple pliers and wire-cutters. If you are using a plastic zipper, you will just be sewing over the top of the zipper tape.

Below (left) is jean fly from my Vado Jean Sew-Along this last summer. Today’s tutorial will be following the jean fly installation quite closely, so feel free to check that post as well. And below (right) is the pair I’ll demo for this post:

OK! So, you will need your marked jean pattern, your facing piece, and your shield piece (next two pictures below). You will also want a jeans zipper (I purchase mine long, and in brass, from Zipperstop), interfacing, and any special bits and bobs for finishing your facing (I used a bias binding, but you can pink, serge or bind!). You also may want to have a few different thread colors; knowing when to match the thread to your fabric and when to go for contrast is a big part of what makes a pleasing look!

A jean fly is ALL about these few square inches on your pattern. I never use the fly facing or shield included in a pattern, but instead I draft my own with a facing piece no smaller than 2″ wide from raw center edge to seam allowance edge:

The shield piece and facing piece, shown below. Note the marked intersection point on the facing, at bottom left. I usually cut both these pieces about 3/4″ taller than the pattern piece too, so that I don’t have any drama at the waistband.

So, remember that intersection point on the jean is so important. You want this marked on your facing piece (below) as well as your two fronts. For your facing piece, the curve will face toward the pocket and the right side will face the body.

Here I have that same intersection marked on the jean fronts. I use tape to make sure the thread tacks stay while I’m waiting to sew:

Now, it’s time to size our zipper. On the shield side of the jean (the right side for right-handed people) we are going to clip our jean front straight to that marked intersection point, stopping 1/8″ from the point. In my case, I am using a 3/8″ seam allowance (not recommended unless you are absolutely accurate in cutting and stitching and are sure of your fit – usually your seam allowance here will be 5/8″ so you will clip 1/2″).

Fold and press,  then pin your zipper like the photo, lining up your bottom zipper stop just above the clipped raw edge. The left-most pin will mark where you will be cutting your zipper tape (not quite yet! Good lord don’t cut yet!), and the second pin, about 1″ below, will be the new top of the zipper, where the teeth end and the new stop will be installed.

Before you do any cutting or remove any teeth, unzip your zipper, and safety pin that tab at the bottom so you don’t accidentally zip the pull up and off the zipper tape (ask me how many times I’ve done this)! Now, we’ll use our pliers and wire-cutters to make a shorter zipper (you can see the process here, in my Vado sew-along). On the right is the finished, shortened zipper with the stops re-applied:

Now, set this aside, and pick up the other front leg (in this case, the left). Clip from the raw edge right to that marked intersection:

Take your interfaced facing piece, and cut diagonally, just skimming the marked intersection point. After cutting, finish the long curved edge by pinking, serging, binding, or zig-zagging. I stitched a bias strip to the raw edge, steamed it into a curve, folded back, and ran a zig-zag topstitch:

OMG, admit it – it looks great!

So now, place this facing right-sides to the overlap front (in this case, the left front). Note my facing piece is longer – I mentioned cutting it a bit long, as it’s easy to trim later. The important thing is that the diagonal cut edge of the facing, buts right against that clipped front (left photo). Pin and stitch at the seam allowance, then grade the facing (right photo):

Now either finger press, or steam press, the seam allowances to the facing  and topstitch all these down, about 1/16″ – 1/8″ from the seam. You can use a contrast thread here, or a matching one:

Now, fold this facing back to the wrong side of the jean front. It will fold beautifully thanks to the grading and topstitching we did. This is a good time to mark your topstitching line. You want to be sure you’ll be catching your facing. I mark with chalk. You can use a french curve for your curved bit, or wing it, like I do, because I am hardcore!

Set aside the overlap. It’s time to get back to the other side again.

Go ahead and press your shield piece right-sides together. Stitch along the long curved edge, grade and clip, turn right-side out, and press:

Remember our pressed edge? We’re going to pin our zipper tape to this fold, keeping the teeth about 1/8″ from this fold. And make sure to pin the zipper face up! 🙂

Now, flip this work to the table, and pin the shield to the assembly. You can place the curved edge to the left or the right! For this pair I am placing it to mirror the facing, which results in a a pleasing “u” shape in the finished fly. But, the standard is to have the curve of the shield mirror the facing (you’ll see this in my pink pair, in this tutorial).

Regardless, the shield covers the teeth and the zipper stop. The whole point of the shield is to keep those teeth from snagging on clothes – or flesh (remember the Brooke Shields Calvin ad? Just me?).  Then it’s ready to sew!

And now you’ll see my super-fancy super-secret tailoring trick – SEW SLOWLY! Below I use a zipper foot, and stitch 1/8″ from the zipper teeth. When I get close to the pull I sink the needle, lift the presser foot, pull the zipper up, and continue:

It’s looking super legit!

Now it’s time to join the two fronts! Sew from that marked dot (right where the pin stabs in, in the picture above), down the crotch curve but not to the raw edge. Make sure to sew a firm backstitch:

Place the jean, wrong side down, and lap the folded overlap over the folded edge. Pin closed (left photo). You will notice on the backside, that this will line up the zipper tape. Pin the free zipper tape edge to the facing only. Go ahead and pin that shield out of the way, while you’re at it (right photo):

Getting ready to sew (left photo)! Why is the lighting so dark here? #zipperNoir. Right photo: sewing, slowly. Again, use a zipper foot here and stitch at the same distance from the teeth, as your first side:

 Looking good! Go ahead and remove the shield pins:

Now, we get to do that topstitch! Anyone else feeling REALLY SCURRED that they’re going to sew on top of that zipper stop? Well, you SHOULD be worried! But I’ll walk you through it. You’ll be okay. First, make sure to pin such that you’ll be catching that facing when you stitch.

Go ahead and switch back to a standard zipper foot, if you haven’t already. And sew slowly, but confidently. When you get to the curve, make sure not to lift your presser foot until the needle is down. Use your hand to crank those last couple stitches and make sure you don’t jam the needle into anything scary.

Stop right at the seam! Leave long tails, pull them to the back, and knot them.

Let’s talk about that bar tack – here you can see a pin where I plan to sew it.

The bar tack, besides looking awesome (there are so many great variations on the theme), it provides structural support so the jean doesn’t rip at that juncture. I like to put my bartack as marked below, catching the shield and reinforcing the bottom of the facing:

For best results, I mark with chalk, carefully form a straight-stitch back and forth, and then zig-zag.

Remember how I mentioned that changing thread color will result in a neater fly? Below, you are seeing that: the topstitching thread is yellow on top, and the bartack white, but they were both sewn with a black bobbin thread:

We are almost finished!

For balance, it always looks pretty nifty if the top buttonhole is symmetrically centered between the folded overlap edge and the topstitching fly line. To do this, I measure this width, subtract the buttonhole width (5/8″, in this case), and chalk the front center marking to start my buttonhole:

How lovely are my Singer buttonholes? I use my old Singer attachment – and my grandmother’s 1950 Singer 15-91 machine, and I use a water-soluble stabilizer underneath. Perfect every time! I tear off the stabilizer from the backside – I don’t bother washing it out as I’ll be laundering these jeans in a bit.

Next, I line up my jean fronts and use an awl to stab 1/8″ from the buttonhole’s leading edge – this will be where I install the button!

And there you have it! All finished!

In my next installation, we’ll be installing a button fly. I know that sounds intense – but it’s a little easier than the zipper, promise!

If you have any questions or comments, please don’t hesitate to share them here!