The last time I sewed undies I tried enclosing both of the gusset seams and ended up with a confusing Möbius strip kind of thing that I wasn’t sure would work. I didn’t tack anything either and didn’t sew through all three layers all the way across which made me think there must be a more reliable way to do it.
The enclosing of both seams, or indeed the sewing of undies in general, probably doesn’t matter to many people but sometimes I get a bee in my bonnet and want to work something out so I think about it hard until I fix it. It has to be said that many of life’s problems cannot be fixed like this so it is good to find one that can!
This is what I did this yesterday and it is easier to sew as there is no twisting of gusset and front and back pieces to accommodate but I would advise a little bit of tacking here rather than relying on pins to hold everything together.
I cut my pieces from one size 16 long sleeved shirt which was 95% cotton and 5% lycra.
Two of the pairs are cut with the stretch going across the pieces and one pair was cut on a wonky bias because I wanted to get as many pairs out of the shirt as possible! I used a self-drafted pattern which is a good copy of a comfy pair of pants I own which are now falling to pieces.
Here is the front piece with one of the gusset pieces on top and the other gusset piece hidden underneath. The outside gusset piece will have its right side facing the right side of the front piece.
Line up the edges and tack through all three layers: gusset-front-gusset. That is what I’m going to call the gusset sandwich.
Next, take the gusset that is lying on top of the front and fold it towards you then take the waist edge of the front piece and roll it towards gusset sandwich so that you end up with something like this
Now lay your back piece on the table and flip your rolled up front piece with attached gussets over onto it, lining up the edge of the outside gusset with the matching edge on the back piece with right sides together like this
This looks odd but stay with me here! Hold the inside gusset and tuck it underneath both the rolled up front and the laid out back, to match its edge with the edges of the back and the outside gusset. The back piece will get a bit bunched up and it will all look like this once you have tacked the second gusset sandwich
Carry this little bundle of joy to your sewing machine and stitch along the seams you have tacked. I find stitching very close to unstable edges like this easier with a narrow zipper foot as it drags less and I can see what I’m doing.
Once the seams are sewn and you pull the rolled up bits out from between the gusset pieces you will see that you have
the makings of a pair of pants with totally enclosed gusset seams!
Now bind the legs and waist however you like and put your pants on!
I had enough FOE with a gold stripe to bind the legs of two pairs and the other pair had lingerie elastic sewn straight on without doing any stitching and turning. I don’t bother binding the waist edges of fabric this stretchy which makes a forgiving waistband that never digs in at all.