Invisible and standard zip insertion for dressmaking

Part Ten

From my years of teaching workshops and speaking to customers in the shop, I know that zips can be something that a lot of budding dressmakers either try to avoid or find really tricky. Compared to sewing a seam, yeh the are a bit more fiddly but once you break it down into simple steps and learn a few tricks and tips, it doesn’t need to be as daunting as you’d think. 

In this post I’m going to explain two types of common zip insertion that you can use not only in dressmaking but also if you were doing some home interior projects too and making some lovely cushion covers. There are other types of zip insertion that I will cover in subsequent posts. These include: fly front, lapped zip and exposed zip.

What are the bits of a zip called?

When you are following instructions in a pattern for inserting a zip you might come across some of these terms that refer to different parts of the zip.

Tape - this is the soft kind of fabric bit of the zip - usually its made from polyester but you can sometimes get cotton ones too. There is always a little extension of the tape at the top and bottom of the zip. 

Teeth - these are the little bits that lock together to actually close the zip and they can be made from plastic or metal

Zip pull or tab- this is what you use to open and close the zip. Sometimes they are fancy and more decorative or a bit more subtle to blend in

Stopper - this is the bit at the end of the zip that in regular zips stops the bottom end of it coming apart. In open ended zips like on coats and jackets, it's the chunky bit at the bottom you have to click together before you can close the zip. It can sometimes be plastic and sometimes metal. You can also create your own stopped when you shorten a zip by sewing several hand stitches around the teeth, then trimming the excess bottom bit off.

The invisible or concealed zip

This is my favourite type of zip insertion as I think when it’s done well it looks so lovely and neat and really professional. Sometimes they are called invisible and sometimes concealed, these two terms can be used interchangeably. 

I’ve made a short video just about invisible zips if you prefer to see the tutorial in that format. 

What does an invisible zip look like?

Just like fabric, zips have a right and a wrong side (or a front and back). With invisible zips the teeth of the zip are on the back or wrong side of the zip. This is so that they are hidden and invisible on the inside of the garment or item you are making. 

The tip pull typically looks a bit more slender and minimal as that is the only part of the zip that will be seen once the zip is sewn in place.

How to prepare the zip and fabric for invisible zip insertion

Fabric - you’ll need to finish off the raw edges of the fabric that you are sewing the zip to first - either with a simple zig zag stitch on your sewing machine or with an overlocker (as per the picture below). 

The two bits of fabric that will be held together by the zip should be kept separate - this is no sewing preparation to do with them. 

Zip - I personally (quite controversially) iron my invisible zip before I sew it onto the fabric. This is to help move the teeth to the side so that it's easier to stitch really close to them. 

I open the zip and have a cool-medium iron and one side of the zip at a time, I use my fingers to gently roll back the teeth so that they are sticking up a bit more. I use the edge of the iron and fairly quickly glide down the zip. Afterwards the teeth on that side of the zip should look more upright. Then just repeat on the other side. 

What foot to use on the sewing machine for an invisible zip

When sewing on an invisible zip you need to use a specific invisible foot for the machine. It’s unlikely that your machine came with this foot - it’s usually something that you need to purchase separately but I’d say well worth the investment! 

The foot has small grooves on the bottom that help the teeth of the zip stay upright at you sew. 

How to sew the invisible zip in

The crucial thing when sewing in an invisible zip is that you get the correct side of the zip facing the right side of the fabric. 

Lay the two sections of fabric out with the right sides facing up and the zip in between them with the right side facing up. Turn one side of the zip tape over so that right sides are facing and do the same with the other side of the zip tape. 

Now pin, hand tack or use wonder tape (which is like double sided sticky tape for fabric that washes out) to hold the zip in place. Take account of your seam allowance. If its 1.5cm then you’ll need to move the zip tape away from the edge of the fabric a little bit. 

One side at a time, feed the zip teeth into the grooves on the bottom of the invisible zip foot and stitch it on with the machine starting at the top of the zip. You should still use your fingers to ensure the teeth and staying upright and feeding into the groove properly. 

Stitch as close as you can to the zip pull (which will be at the bottom of the zip) and do a little reverse. 

Repeat for the other side of the zip.

How to finish the invisible zip off

The next stage is to sew the rest of the seam below the zip. I change to the regular zip foot for this part at it allows you to get nice and close to the zip at the bottom. Make sure the zip is closed before you start. 

If I was sewing a dress or skirt for example, I like to start at the bottom hem and stitch up towards the bottom of the zip. Make sure you are sticking to the correct seam allowance for your project. 

As you approach the bottom of the zip, use your right hand to hold the zip to the side and the aim is to get the stitching of the seam to exactly meet the stitching that is holding the zip in place. They shouldn’t overlap at all or you will get a little bubble at the bottom of the zip. 

Check the zip can glide up and down easily. If it doesn’t you may have sewn too close to the teeth so those sections will need to be unpicked and stitched again. 

Finally, be sure to press the seam allowances open for a nice crisp finish! 

The standard zip - centred insertion 

Find this tutorial in video format in this Youtube video.

What does the zip look like?

On standard zips the teeth are on the right side of the zip and the zip pull is usually a little more chunky than an invisible zip. 

How to prepare the zip and fabric for insertion

My preferred method of inserting a standard zip is to first base the fabric together with the sewing machine. It’s also easier if you finish off the raw edges of the fabric first, just as suggested for the invisible zip insertion. 

Put the two sections of fabric, right sides together and line your zip along side. Mark with chalk or a pin, where the top and bottom stopper of the zip is. 

Sew the two sections of fabric together with a regular 2.5mm stitch length and a back stitch above and below your markings and in between the markings, use a longer basting length such as 4.5 or 5mm. 

Press the seam allowances open.

What foot to use on the sewing machine

Your machine is likely to come with a standard zip foot. On my machine it looks like this and it allows you to stitch close to the raised teeth on the zip. 

How to sew the zip in

I like to use the Prym wonder tape to hold the zip in position before I sew it but you could hand tack it on instead. If using the wonder tape stick it along both sides of the zip tape on the right side and then place the zip face down onto the seam allowances of the fabric, making sure that the teeth are centered over the seam line. 

From the right side or front of the fabric, unpick some of the basting stitches around the pull of the zip - around 2 inches should be enough. This is so that as you stitch the zip into place you can move the bulky zip pull up and down so you don’t have to stitch around it.

Make sure you can see your markings of where the basting and regular stitching changes at the top and bottom of the zip - either with a pin or some chalk. 

With the zip foot on the machine, you are then stitching a rectangle of stitching, about 1cm away from the seam line all the way around. 

To help keep this line of stitching even there are a few things you can try

Draw a stitch guide on with chalk - just check and test the chalk will come off easily afterwards as some fabric can really hold onto chalk marks

Use a landmark around the foot of your sewing machine to tune your eye into, it might be keeping a certain part of it lined with the seam line - every machine will be slightly different so whatever you can use to help. 

Have a seam gauge or little ruler handy to keep checking you are lined up evenly. 

How to finish it off

Once the stitching is in place and you have checked to make sure that the tape of the zip has been caught in the stitching from the back, it's time to unpick those basting stitches and check that you zip can glide up and down nicely. 

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