For the swing shorts I wanted to make a button fly instead of a regular zipper application and since I have a great vintage sewing book that explains this process well, I decided to try it out. And it turned out to be quite easy (albeit more time consuming compared to a regular zipper). So I thought I should share the method I employed, mixing the vintage method with some modern hacks.
1. Cut and interface two fly shields
When making a button fly you’ll need two shields. One for the buttons and one for the button holes. The two shields should be the same size and shaped like an “U”. As for the sizing, they should be the about the same size as the fly facing that is usually included in the pattern.
2. Interface the left fly facing where you will topstitch the button fly
3. Fold both shields and sew the curved bottom and the sides
4. Turn and press
I like to use a bamboo point turner for shaping the corners.
5. Sew the buttonholes on the buttonhole fly shield
In my vintage sewing book the buttonholes are slanted which I think is a nice detail, so I replicated that.
6. Topstitch the straight seam on the buttonhole fly
I recommend using a blind hem presser foot for this step as it creates an even edge seam.
7. Now topstitch the button shield
This time you’ll edgestitch the rounded side.
8. Trim the right side fly facing
Only 1.5 cm (ca ¾ inches) seam allowance should remain. This is where you’ll attach the button shield. This step is an deviation from the vintage method because it calls for lining the trousers and you then attach the shield to the lining. But since these shorts are unlined I’ll use the same method that I employ for my jeans zipper application.
9. Attach the button shield to the trimmed right-fly piece
10. Fold over the fly piece and edge stitch to keep it in place
11. Attach the buttonhole fly shield
You do that on the left fly facing using an edgestitch
Sew the crotch seam of the front pieces together finishing where your mark is. You will then sew the back crotch pieces together, the outer side seams and finish off by sewing the inner leg seam from one leg opening to the other. This is just like jeans are made and I’ve done a tutorial on how this works.
13. Finish off by topstitching the button fly
Just like you normally would. The book also suggests topstitching a little “triangle” to keep the shields in place, so I did that too. Next you’ll attach the waist band and the fastening for the waist, just like regular trousers.
Hope you found the tutorial useful. If you have inserted a trouser zipper with a fly shield before you’ll have no problem doing the button version too. The principles are pretty much the same, only difference is that you’ll need to make a second fly shield.