I think sewing an invisible zip is a rite-of-passage for dressmakers !
Invisible zips look lovely if they’re done well, but sewing them can be difficult to get your head round. It’s the opposite of sewing a conventional zip.

I tried to learn from the internet and got very confused. A multitude of methods, most not well explained.
I couldn’t understand about pressing the zip. Until I opened one and saw that it folds over on itself.

Want to watch someone doing it ?
There’s a good video tutorial in the Craftsy free class on zipperss.
Makes it look easy, but there are many details to get right.

The best written instructions I found are in Vogue Sewing 1982. So here they are, with my comments added – so much to say, this post is long.

This method uses an invisible zip foot. There’s no need to press the zip, as the foot rolls the zip coils into place. The foot also puts the stitching in the right position next to the coils.
So it’s my favourite method.

More skill needed to use a conventional zipper foot, as you have to choose where to place the stitching.
Notes at the end of this post on sewing an invisible zip using a conventional zipper foot.

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Preparation

Fit your invisible zip foot to your machine. With the pointy bit towards you. That unfolds the zip coil into the foot groove.
You can get a foot specifically for your machine.
There are generic ones supposed to work on any machine with the same foot attachment. I have a generic foot, but it doesn’t fit my machine. There are two standard widths of clip-on feet, so check a generic foot fits your machine before buying !

Quick foot recognition : Several presser feet have two grooves on the bottom. This one usually has a narrow needle hole, plus the piece at the front for unfolding the zip. Cording and pintuck feet have a hole wide enough for zigzag stitch or twin needle.

Check your zip. Conventional zips with plastic coils and invisible zips look similar. Both types have one side where the coils show, one flat side.
On an invisible zip, the zip pull is on the flat side. The flat side is the front. When you open the zip, you find the coils are folded back.
On a conventional zip, the zip pull is on the same side as the coils. The flat side is the back. Faces into the garment, so the zip feels smooth against the skin.

Use a zip at least 1-1/2”/ 3-4 cm longer than the finished zip opening, so you can move the zipper pull out of the way while stitching.

It helps to mark the stitching lines on the right side of the fabric – makes it easier to position the zip.

If your fabric has ‘give’, fuse strips of interfacing under the stitching lines to stabilise the fabric.

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Method adapted from Vogue Sewing 1982

The invisible zipper, which has no rows of stitching on the outside of the garment, must be stitched with a special invisible zipper foot.
Unlike other zippers, the invisible zipper is applied to the opening edges before the remainder of the seam is stitched. It’s also stitched from the right side of flat fabric.

Step 1 – right side of zip

”invis

(Blue is right side of fabric, white is wrong side of fabric. Zip opening is at left side of this drawing.)
Open the zipper and place it face down on the right side of the fabric.
(The face of the zip is the smooth side.)
Have the folded teeth/coils lying on the seamline and the tape in the seam allowance.
Lower the right hand groove of the foot over the teeth (hold the coil to the right to get it started into the groove)
and stitch from upper edge to pull tab.
Back stitch at both ends of stitching.

An invisible zipper foot places the stitching at the correct distance from the coils (for most fabrics).
If you’re using a conventional zipper foot, try to stitch down the ‘fold line’ of the zip. Further away from the coils and the zip won’t be invisible. Too close and the zip may not open and close.

Trim threads closely. Coil zippers get damaged easily when you try to pull out threads caught in the coils.

Step 2 – left side of zip

”invis

Close the zipper.
Fold the first piece of fabric back from the zip. Place the zip face down on the second piece of fabric, middle of the zip on the stitching line.
Pin or baste as desired.
If you need to match the fabrics, draw a line across the zip at an easily recognisable point.

Open the zipper
and stitch with the left hand groove of the foot over the teeth.

Step 3 – seam

”invis

Close the zipper.

To finish the seam below the zipper, slide the zipper foot to the left.
If your foot won’t move sideways, try moving the needle to the right.
My invisible zip foot doesn’t slide, and is too wide to move the needle past it. I use a conventional zipper foot for this step, placed to the left with the needle to the right.

Pull the end tapes of the zip out of the way.
Make sure the rows of stitching at the bottom of the 2 sides of the zip are aligned sideways (push a pin through to check).
The ends of the 2 rows of stitching are unlikely to align lengthwise, that doesn’t matter.
I pin the seam allowances together at the bottom of the zip, to make sure they’re out of the way.

Lower the needle and begin stitching just slightly above and to the left of the last zip stitches. About 1/16”/ 1 mm left. Further away and you’ll get a pucker of fabric at the bottom of the zip.
The first time I tried this I had to do it several times before I was happy with the result. I still sew the first couple of inches and check, before completing the seam.

Stitch seam closed.
Backstitch at beginning and end of seam.

Step 4 – neaten end of zipper

”invis

To complete the application, machine stitch the zipper tape ends to the seam allowances.

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If you haven’t got an invisible zipper foot

If you’re using a conventional zipper foot, press the zip coils flat :
Open the zip
and place it on the ironing surface with coils up.
Press the zip coils away from the zip tape, so they’re a bit flattened but not squashed. You want the zip unfolded, but so you can still see the fold line.

Then sew in the same way as above, but set the zipper foot so you can sew in the ‘fold line’ close to the zip coils.

Step 1 – right side of zip – zip foot to left of zip coils, on zip tape.
Step 2 – left side of zip – zip foot to right of zip coils, on zip tape.

Once you know the process, you can unfold the zip coil with a finger as you sew. No need to press the zip flat first.

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With thanks to the book Vogue Sewing 1982, which includes the text and diagrams on which this is based.

There are many methods for sewing an invisible zip, using different presser feet and ways of pressing.
Some experts prefer an adjustable conventional zipper foot, because you choose your own placement for the stitching. So, for example, you can allow for the thickness of the fabric.
Experiment to find a method that you’re comfortable with.

When you’ve done this a few times, hopefully it will all be clear and simple 😀

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