Dear readers,
I need to be clear about this one. This tip comes with a disclaimer: there are alternative views, and pressing direction is a recurring debate in my own studio. I can hear a colleague of mine gritting her teeth as she reads this. So consider this a guide to the most common conventions, not an absolute law.
That said: there are conventions. And knowing them gives you a useful starting point for every seam you press, even when you decide to deviate from them.
Open or pressed to one side?
Press open when: seam allowances are finished separately; you want to reduce bulk (especially in tailored or lined garments); or you may need to let the seam out later.
Press together to one side when: seam allowances are finished together for speed or strength; it helps a detail lie better (pockets, gathers, pleats); or for all enclosed seams such as French seams and flat-felled seams.
Side seams, underarm seams, shoulder seams
Finished together: press toward the back. This keeps the front smooth and clean, and is usually necessary when there are pockets in the side seams.
Finished separately: press open. This is standard in tailoring and allows catch-stitching to the interfacing.
Inner leg seams
On jeans and knit trousers: finish together and press toward the back for durability and a clean finish. On tailored woven trousers: finish separately and press open. Crotch seams are usually pressed to one side and finished together, given the stress that area takes.
Armscye seams (set-in sleeves)
Usually pressed toward the sleeve. This helps shape the sleeve head and keeps the bodice smooth. Occasionally pressed toward the bodice when a softer sleeve head and rounder shoulder are preferred. On dropped shoulder designs, it depends on the design and your preference.
Waist seams
Usually pressed upward, toward the bodice or waistband. The bottom section is often fuller (gathers, pleats, darts), and there is usually a facing or lining at the top to cover the seam allowance. On fully lined garments where both sections have equal bulk, pressing open is standard.
And darts? Those follow their own pressing rules, and that is a Tiny Tip for another Tuesday.
Happy sewing,
Delphine