Cushion Cover With an Invisible Zip

By the end of this you will have a cushion cover with a closure nobody can see — no visible teeth, no lumpy zip flap, no button placket. Two squares of fabric, one seam that happens to hide a zip, and a corner trick that stops the finished cushion looking like a ravioli. It is the first project where your work stops reading as homemade and starts reading as bought, and the whole thing takes about two hours.

That is the reason it sits at Stitcher level rather than earlier. Nothing here is difficult on its own; the invisible zip is just a straight seam sewn very close to a coil. But it rewards going slowly, and it punishes a rushed press.

What you need

Things you probably already have: pins or clips, a fabric scissors or rotary cutter, a tape measure, and an iron. If you are choosing between cutting tools, rotary cutter vs scissors covers when each one wins — for two big squares, either is fine.

Cut list

Everything below includes a 1/2-inch seam allowance on all four sides. Cut two identical squares:

• Front panel: 19-inch by 19-inch
• Back panel: 19-inch by 19-inch

That gives a finished cover of 18-inch square, which is deliberately the same size as the pad rather than bigger. A cover cut to the exact pad size stretches slightly over the filling and stays plump. Cut it a half-inch generous and you get the sad, saggy cushion look.

Half a metre of 54-inch-wide furnishing fabric holds both squares side by side with a little left over. If your fabric has an obvious pattern direction, check both squares run the same way up before you cut.

Steps

Prepare the zip

1. Press the fabric first, not later. Creases from the bolt will throw your cutting off by more than you would guess, and you cannot press them out convincingly once there is a zip in the way.
2. Press the zip tape flat. Set the iron to a low synthetic heat and gently roll the curled coil away from the tape from the wrong side, so the teeth stand up and the tape lies open. You are trying to expose the coil so the foot can ride over it. Do not park the iron on the coil — it is plastic.
3. Thread up with a fresh needle in. A blunt needle skips stitches on furnishing weight. If your machine setup is still shaky, how to thread a sewing machine is the two-minute refresher.

Attach the zip

4. Open the zip fully. Lay the front panel right side up. Place the open zip face down along the bottom edge, coil sitting about 1/2-inch in from the raw edge, with the zip pull and the tape ends running off the fabric at both ends.
5. Fit the invisible-zip foot and drop the needle into the correct position for the groove you are using. Sew from the top of the zip down, letting the coil feed into the groove. The foot holds the coil upright so the needle lands right beside it — that closeness is exactly why the seam closes over the teeth afterwards.
6. Stop about 1-inch before the zip pull. You physically cannot sew past it. Backstitch, cut the threads, and leave that gap; the main seam will close it.
7. Repeat on the back panel. Right sides together, second zip tape along the second panel's bottom edge, same 1/2-inch position, same direction of sewing.

Close the cover

8. Close the zip and open it about a third of the way. If you sew the rest of the cover with the zip shut, you have made a cushion-shaped bag with no way in.
9. Pin the two panels right sides together around the remaining three sides. Where the seam meets the zip, swap back to your standard or zipper foot — the invisible foot cannot handle the bulk.
10. Sew the three sides at 1/2-inch, starting your stitching a little past where the zip stitching stopped and overlapping it by about 1/2-inch. That overlap is what makes the gap by the pull disappear.
11. Blunt the corners. Instead of a sharp right angle, take two or three stitches diagonally across each corner. Trim the corner seam allowance back to about 1/4-inch afterwards. This is what stops the finished corners looking like little pointed ears.
12. Turn it right side out through the zip, push the corners out with something dull — a chopstick, not scissors — and give the whole thing a final press with the seams rolled slightly to the back.

When it goes wonky

What you just learned

• Installing an invisible zip, which is the same technique used on dress side seams and skirt backs — it is not a soft-furnishings-only skill.
• Swapping presser feet mid-project, and recognising when a specialist foot is doing work no amount of care can replace.
• Cutting to a finished dimension, adding seam allowance deliberately rather than guessing, the same arithmetic you will use when you read a sewing pattern.
• Corner control — blunting and trimming so a turned corner looks sharp instead of stuffed.

If you enjoyed the zip more than the square, try the zip pouch project in the library next; if you preferred the pressing and the crisp corners, the lined tote bag project builds on the same finishing habits. Either way, the rest of the Stitcher level will start feeling noticeably less intimidating from here.