This is kinda basic, but something that I actually didn't really understand for years...until it was made clear to me by Claire Shaeffer when I had her to my shop years ago. On this apron 'tie', the piece is folded, right sides together. The fold is along the left hand side. I stitched across one end, then up the long raw edge side. Then it is turned right side out .....
BUT, you have to 'picture' the seam allowances once the piece is turned right side out. The corners are NOT the same issue.
The corner on the left - where the end intersects the fold - should NOT be trimmed at an angle. Until Claire made it clear, I always trimmed each corner - even when it was at a fold. She helped us realize that the seam allowance of the end, when turned right side out really is needed along the folded edge to SUPPORT the end. Thus it is is not trimmed at an angle.
The corner on the right - where the 2 stitching lines intersect - is trimmed at an angle correctly. 'Picture' the seam allowances as they will be when the tie is turned right sides out ... only by trimming it at an angle as you see above, will the seam allowances have a place to lay. Without trimming at this angle, you would have a 'wad' of fabric scrunched into the corner.
1. Press it all - as you see it, except do not press the fold. Pressing the stitched lines 'seals' the stitching - helping the thread embed into the fabric.
2. Press the seam allowances OPEN. This should always be done for any seam that will end up laying on an edge. In this case, I was able to press one of the layers of the long edge downwards.
3. Then, I used the eraser end of a pencil pushed against the seam at the end to get the apron tie 'turning' right side out. See the photo below.
4. Once turned right side out, press carefully, getting the long stitched edge to lie 'on the edge' - which will be much easier since you pressed that seam allowance open.
5. A pin can safely pull out the corners so they look nice and square.