Since I’ve started designing patterns, I’ve noticed that people seem to be intimidated by sewing functional flies. I sewed my first about four years ago with a Blank Slate pattern – I don’t even remember which one now. I do remember thinking “Hey! That was cool!” and I’ve been sewing them ever since! I’ve used a lot of different patterns and methods since then and have come up with my own way of sewing them, which is really easy – I think so anyway ;) And for a bonus, there’s a section at the end for doing a faux fly!
I actually have these instructions printed out and pinned to my wall in my craft room as a reminder (especially if I’m doing a girl’s fly, I tend to get turned around!). I have them here as PDFs, separated into girl’s and boy’s. There are only two pages in each file, and I’ve used illustrations so they won’t eat up your ink if you’d like to print them out as well. I’ve had several people ask for the instructions with pictures, so that’s what we’ve got today!
I know everyone has their preference for pictures/illustrations for patterns. I prefer illustrations because I like the clarity, but I snapped some pictures for those who prefer those.
NOTE: For this tutorial, right and left refer to right and left as you are looking at the pictures and not the wearer’s right and left. Also, this is for a boy’s fly. For a girl’s fly, you’ll be doing it the opposite way (download the instructions above – it helps to see them actually flipped).
Place your front pieces RST (right sides together). Sew along the crotch seam using a basting stitch above the circle marking and a regular stitch underneath. Cut at the corner of the fly to the circle marking (where I’m pointing), being careful not to cut the stitching. Finish the raw edges of each side of the fly separately. Finish the rest of the crotch seam below the marking. Also make the zipper shield according to the instructions. Switch to a zipper foot to make the rest of the fly easier.
I have sewn over the metal stop at the end of the zipper so many times that I’ve finally just started cutting it off! I replace it with a bartack after I’ve finished the fly and I think it makes everything easier to sew. Just remember not to unzip until it’s secured ;)
Flip the jeans over. Make sure the free edge of the fly is folded out of the way. Pin the shield on top of the zipper tape with the edge of the shield at the edge of the tape. The bottom of the shield should be at the bottom of the curve of the fly or slightly (1/4″ or less) above it. After I took the next few pictures, I unpicked the shield and moved it up about 1/4″ – this makes it much easier to topstitch later on.
Turn the jeans over so you’re working from the right side. Make sure the fly is lying nice and flat, but keep the shield pinned over to the left so it’s out of the way. Feel the right edge of the fly through the fabric with your fingers. I like to use a fabric pencil of some sort to mark the edge of the fly. Continue marking the bottom of the curve. This is why I moved the shield up a little – if I sewed exactly on the curve of the fly, I would have caught the bottom of the shield and it would have ended up not laying flat.
Press the rest of the crotch seam allowance to the right. Topstitch along the marking – at the bottom, plant your needle and turn the jeans so you can topstitch along the seam.
Here I’m pointing at the topstitching from the wrong side of the fabric. By placing the shield slightly above the bottom of the fly and the topstitching just at the bottom of the fly, the shield isn’t caught in the stitching.
Un-pin the shield and let it lay flat behind the fly. Right where the topstitching starts curving, make a bartack, being sure to catch the shield in the stitching. Fell through the fabric to find the zipper. Make another bartack right on the zipper teeth to close the end. If you used a metal zipper, don’t sew on the teeth – make your bartack just to the left (closer to the center seam) of the teeth and be very careful not to sew on them!
If you’d rather do a faux fly, they are the easiest thing in the world! I prefer to do them for my younger boy because we’re potty training and it’s easier to get off quickly. You can do a faux fly on any pants patterns, but I recommend doing a muslin first. Put it on the child with the wrong side out and pin the fly closed to see if it will comfortably go over their hips and waist.
Back to illustrations!
I like to leave the basting stitches in until I’ve finished attaching the waistband. Keeping that folded edge tacked down means it won’t get twisted or lumpy when you’re sewing. After the waistband is added, remove the basting stitches and you’re done!