In the following unit I have used contrasting threads to help you see where I have sewn for the demonstration, obviously usually you would use less noticeable thread on your garments.
I have also used scraps of fabric for demonstration purposes rather than fabric garment pieces.
As with all units it will help to review the section you are interested in first before you try out the method.
Zips come in lots of different lengths, colours, plastics, metals and can open all the way down as in a jacket or will be stopped at the bottom such as in a skirt or dress. They can be used functionally or for decoration in seams or simply applied as an applique.
There are three main types of zip installations;
An Invisible Zip installation (which is requires an invisible zip)
A Standard Centred Zip installation
A lapped Zip installation
Before you start it does help to have the appropriate tools to hand and one thing that will make life much easier is an invisible zipper foot for your sewing machine (although of course you could hand sew the zip in place if you prefer and it would be just as strong). Most sewing machines come with a zipper foot that you will also find useful. Mine is the number 4 in the photo, it makes you shift the needle to either side of it to help you get closer in to the zip teeth as the foot glides down the zip tape helping to hold it in place as you sew. Usually you will need to purchase the invisible zipper foot separately and it really helps to have one if you are going to be sewing lots of invisible zips over the years, mine is the number 35 in the photo. The instructions here will use both zipper feet for the installation of an invisible zip so if you have both feet the installation will be easier. Having said this you can get by with the standard foot supplied with your sewing machine.
If you have never installed a zip before practice first before you try it on your garment to ensure you understand the process and how everything lines up. Getting a zip in perfectly can make the difference between your garment looking like a craft project or looking like a perfectly sewn garment and one that you will want to be proud to wear. If things do go wrong and they can sometimes don’t worry just pull it out and start again.
One thing to decide on is how to finish the seam edges of the garment which you may have already done for the rest of your garment, so whatever you have chosen as a seam finish do the same on the back seam before you install the zip whether you are overlocking by machine or binding etc. In the following examples I have left the edges without a seam finish and you can do this too depending on your fabric or simply cut the edge with your pinking shears.
One other important item is a strip of interfacing or a stay to add to the fabric under the zip on both sides which can help to support the zip if you feel the fabric needs this extra support. Experiment with your interfacing, any type will give you more support for the zip so don’t over think it. The size of the interfacing or stay should be at least the length of the zip and at least the width of the seam allowance + 1/8” you would need two pieces one for each side of the zip. Read the instructions below first before cutting your interfacing as each zip is slightly different. Either press with the iron in place or if you are using a cotton or silk organza stay baste it into place.
Also consider your zip size as it is not always possible to buy a zip the exact size that you want or you may have one in your stash that you want to use that is longer. Always go bigger when buying a zip if they do not have one in your size.
All zips can be adjusted in length and shortened. You may wish to make use of the extra length to get you zip pull out of the way during construction so read the instructions below first before making any decisions on length.
Check the length of the zip on your pattern from the top stitching line to the notch for the zip end. If your zip is too long and you choose to cut it down before you start (more than 1” too long) then adjusting the zip length is a very simple thing to do. Measure and mark on the zip where the new zip end needs to be and create a zip stop by simply stitching over and under the zip teeth several times at this point and ensure that the thread is very secure at the beginning and at the end of stitching.
Test the zip to ensure your little thread stopper works.
Then cut the excess of the zip away (using a pair of old scissors not your sewing or paper scissors!) allowing at least ½” of zip below the zip stop you just created.
One final but picky point to make about adding in zips is that usually we wear zips with the zip closed and the pull tab sits at the top. When you install the zip consider that the zip pull uses a little extra space here at the top so if the zip is installed with the tape set back just a little further at the top then this helps to keep the garment looking closed rather than pulled slightly at this point. Consider this when you baste your zips or position your zips in place.
Invisible Zip Installation
There is one zip in particular that I prefer simply because I am amazed by how simple it is to install and also the fact that it goes into the garment almost unnoticeably and that is the invisible zip. When installed there is no stitching visible and no zip visible.
The installation would be the same regardless of whether you are installing it in a top, dress or a skirt or trousers.
When the invisible zip is zipped up even before you install it you can see that you cannot see the zip teeth from the anterior side. The Black zip in this photo is an invisible zip, as you can see the zip pull is a more elegant oval shape so it makes identifying these kind of zips a little easier. I think that they are prettier because of the zip pull.
An invisible zip really has coils that roll under rather than teeth like all the other zips.
We saw during drafting patterns for zips that you should mark the position of the bottom of the zip on the draft so that this area can be notched and if using a seam allowance that you may wish to extend the seam allowance size in the zip area to ¾” although this is not essential ½” would be sufficient I just think the wider seam allowance is better as it grades everything you don’t have a big wedge of fabric and zip ending at the same point.
To prepare the fabric regardless of whether you have predefined a seam allowance size or not it will help to mark the sewing line in the zip area. I prefer to thread trace the sewing line to show its position. I do this regardless of the type of zip and installation chosen.
Here you can see that the interfacing has been attached in the zip area. The following areas have been marked by thread tracing; he seam allowance for the zip, the seam allowance for the seam below it and the seam allowance for the top (which could be the top of the dress or the top of the skirt or where a waistband would attach).
You can see that I have made the interfacing a little wider than the seam allowance in the zip area so that it gets caught in the stitching line and supports the fabric on the garment side. But only do this if the fabric can handle it and you are sure it is not going to show through on the anterior side of the garment. If using a lining the whole thing including the zip will be hidden anyway. If you feel the fabric does not need the extra support of the interfacing or stay strip then of course you don’t have to use one.
The invisible zip is installed prior to stitching the seam below it.
It does not really matter which side of the zip you attach first but I usually start with the left side (left when viewing the garment from the anterior side) just out of habit really. In the previous photo as you are viewing from the posterior side that would be the one on the right.
With the zip closed place the zip face down onto the anterior side of the fabric lining up the top of the zip with the sewing line at the top of the garment.
Line the centre of the zip directly on top of the sewing line.
In the seam where you are going to stitch the zip pin the zip tape to the seam allowance holding it all in place. Keep checking the zip position underneath to make sure it is all lined up. I place my pins parallel along the tape heads down as this holds the tape a little better I think and it is easy to take them out as you stitch.
It is a good idea to test out this next step if you have never done it before, when stitched you want to be able to open the zip but not have the stitches too far away and this will take a little testing out with your needle position on your sewing machine. I know that my sewing machine works fine if I leave the needle position as it is but you will need to experiment a little until you get it right then you can install the rest of your invisible zips using this setting.
For the next bit if you don’t have an invisible zipper foot you can install an invisible zip with a standard zip foot but it may be a good idea to press the coils out with an iron prior to sewing to flatten the zip out a little, you will get in a little closer then with the stitching. But you don’t need to do this step if you do have an invisible zipper foot to install the zip.
So place the invisible zipper foot on the sewing machine. Open your zip by pulling the zip pull all the way down to the stopper.
Place the zip into the foot ensuring that the top of the zip (not the top of the zip tape) is lined up with the top horizontal stitching line and roll the zip edge back with your finger until it slots into the zip foot like this.
Start to stitch down the zip securing the first few stitches by reverse stitching for a couple of stitches.
Then continue stitching down the zip removing the pins as you go, ensuring that the position of the zip does not slip around as you sew (you could baste down the zip rather than use pins if you prefer especially with fabrics like satins and silks).
When your zipper foot hits the zip pull at the bottom and you can stitch no more then stop and securing the end of the stitching with a few reverse stitches to ensure everything is well secured.
Snip off your thread ends then close up the zip to check the zip closes and the position of it on the fabric and continue if you are happy everything is fine.
Place the zip face down onto the fabric pattern piece on the anterior side and pin down the other side of the zip lining up the centre along the stitching line again.
Pin into place.
If you prefer you can baste this side down (smaller basting stitches work well to hold the zip in place) and then test the zip by opening and closing it, this is useful if you zip goes through a horizontal seamline that you want to line up say for a waist seam. You are checking that everything lines up before you commit to sewing.
Open the zip then sew this side into position using the other side of the sewing foot. Sewing in the same way as before.
When you have stitched check under the zip to ensure that both lines of stitching have ended at the same point.
Check that the zip is installed to your liking by turning to the anterior side of the garment and zipping and unzipping a couple of times. Make sure that it zips smoothly and that the fabric is close enough to the zip to hide it and sewn evenly all the way down.
The next step is to stitch the seam below the zip. So close the zip and pin the seam together from the zip downwards, if you prefer then baste it into position.
At this point I would change my zipper foot to the standard one that comes with the machine to stitch the seam, the needle will need to be adjusted to the side of this foot in order to stitch but I find that this foot gets you closer to the bottom of the zip.
I will usually start at the base of the seam and sew up to the zip. If you are confident that your seam is precise and take your time you should have no problems with the seam by the time you get to the zip. Of course if you prefer you could start from the bottom of the zip and sew downwards. At the zip end point the seam stitching ends up being around 1/4” above the end of the zip stitching and slightly to the left of the zip stitching. When you stitch up to the zip you will have to pull the bottom of the zip up and out of the way. Ensure you really secure the stitching at the beginning and at the end of sewing by reverse stitching a couple of times.
The last step is to secure the base of the zip down onto the seam allowances, ensure that you stitch only through the zip tape and the seam allowance on both sides for around ¾” and I use the zip foot that came with the machine to get you closer to the zip.
You could now press the fabric a little around the zip being careful not to melt the plastic on the zip.
Standard Centred Zip Installation
A standard centred zip has the zip installed directly on the seam and is centred and it has stitching down both sides and across the bottom of the zip area.
Sewing the top of standard centred zip can be a little tricky so consider buying the zip 1” longer than you need it to be and when you position the zip extend this extra 1” up from where you are finishing the zip at the top, you can then use this extra space to take the zip pull out of the way while you sew then bring it back down. Although I have not shown this method this point is mentioned again later in these instructions so it’s a good idea to read them all through before you begin to work out how you prefer to do this.
With a standard centred zip installation you can use the same seam allowances as you would do with an invisible zip, you would thread trace your sewing lines in the same way and also apply interfacing in the same way.
In a standard zip installation the seam is stitched before adding the zip.
With anterior sides together pin the seam down the stitching line from top to bottom.
Stitch the stitching line for the seam from the very top edge of fabric to the base in one go but you are going to stitch the zip area from the top to the zip notch (where the zip ends) with a basting stitch around 5mm, then back stitch a couple of stitches then stitch the rest of the seam with a usual length stitch around 2.5mm. There is no need to backstitch at the top but ensure you backstitch at the end of the stitching at the base. Obviously you could sew it all in the other direction if you prefer.
Press the seam (as usual sandwich press, press open on posterior side then press on the anterior side), and if you added thread tracing stitches on the seam you can now remove these if you want to.
Next ensure the zip is closed and pin the zip into place face down on the posterior side of the garment. Lining up the top of the zip with the top stitching line on the garment and lining up the centre of the zip on the seam line. If you have a zip 1” longer than you need the stitching line will be lined up 1” down from the zip top (the zip top is where the teeth end not where the tape on the zip ends).
The zip needs to be attached in some way to hold it in place while you sew it and you can either sew it by hand using a prick stitch or back stitch doubled thread for extra strength, wax coated works best or sew it using a machine. As I prefer to stitch the zip from the anterior side of the fabric because you can see much better how far from the seam line you are stitching it is a little awkward to use pins to attach the zip. So I pin first then baste the zip into place. Some people use tape but I really don’t like getting tape on my needles and I think a little lost thread is a little better on the environment than thrown away tape.
Baste the zip into place ensuring that you get the same amount of zip on each side. I generally follow the little guideline that most zips have on the tape where the weave looks slightly different you need to baste 1/4” away from the centre of the zip. I also place a pin on the anterior side below the zip stop as you will need to stitch underneath the zip stop when attaching the zip, if you try to sew on the zip stop you will break a needle. I place the pin on the anterior side so it’s easy to remove when you get to that point in the stitching. Here is the anterior view after basting.
And here is the posterior view.
And check by turning to the anterior side to have a look and assess your basting stitches making sure they are reasonably straight and ¼” away from the seam and the same on both sides.
The next step is to stitch the zip into place on the anterior side. Using a standard zip foot position your needle so that the foot base is away from your zip and your needle is ¼” away from the seam or on you basted line. Start by backstitching at the top to secure it then stitch down one side, turn the fabric with the needle down then stitch along the bottom (here you can back stitch all the way back and restitch the bottom if you want a little more strength in the zip) then you turn and stitch all the way back up the other side and finally back stitch to secure it. If you don’t trust yourself to stitch straight lines you can mark the stitching line all the way around with chalk if you prefer.
If you are finding that the zip pull underneath is going to distort your initial first few stitches because of the bulk of the zip tab underneath you can start stitching an inch or so below this point stitch all the way around then come back and finish and stitch the top on either side after you have unpicked the basting and pulled the zip tab down. I usually find that I can get a good straight line of stiches in because the foot is so far away from the zip.
I also have this tool with my sewing machine that allows you to place 1/2 or 3 pieces of plastic under the foot behind the stitching to raise the foot up and I use it at the beginning of stitching a zip for the first dozen stitches, I find it does help but you do have to watch the position of everything if you use one of these as things can slip around a little.
The other way to deal with this is if you have chosen a zip 1” longer than you need and you have the extra 1” hanging off the end at the top and you can move the zip pull out of the way in order to sew. The excess is then removed after by simply cutting it off but you will then need to ensure you never pull the zip pull off the ends by accident so you will need to stitch thread stops on each side of the zip by stitching under and over the teeth to create a little wall of stitches on each side as described above when looking at how to shorten a zip.
Pull out the basting stitches.
Cut open the machine basting stitches to the base of the zip where you backstitched
Installation finished so give it a little press.
Lapped Zip Installation
A lapped zip has an overlap hiding the zip and the stitching on the other side underneath. You see only one line of stitching on the overlap side and stitching across the bottom of the zip area.
It is up to you which side you overlap on the zip but usually a lapped zip has the overlap on the left hand side overlapping the right side of the zip so that you only see one line of stitching. There is no real advantage of a lapped zip over a standard centred zip other than design and personal preference. Although I personally think stitching a lapped zip is a little trickier as there it is a little more involved.
It is important when drafting a lapped zip to define very carefully the seam allowance for each side and determine how wide you want the overlap to be at the drafting stage. There is a slight overlap of 1/8” so if you are making a very tight fitted garment you may wish to consider the loss of 1/8” on the left side, you use 1/8” from the seam allowance from the right side so would not need to add anything on the right. It also makes sense to ensure that the stitching line on the overlap side of the zip incorporates the seam allowance to hold it out of sight. If you wanted to you could have one seam allowance larger than the other with the widest being on the overlap side such as draft ½” for the underlap and 5/8” for the overlap side.
In the example shown here I have allowed 5/8” for both sides for a seam allowance to allow both seams to be the same down the back of the garment.
The interfacing is attached to the zip area as before and the sewing lines are thread traced as before.
You need to make sure that the interfacing covers the area where the zip and stitching is which includes the seam allowance stitching area and just passed it so use 1” wide for the underlap (right side) and about 1 ¼” wide for the overlap left side.
The seam below must be stitched prior to installing the zip.
Before you stitch the seam check the length of the zip and where the zip notch is ensure that the top of the zip (not the tape on the zip) starts at the top stitching line and ends at the notch, you can decide if you want the zip stop to be below the seam line, on it or above, it does not make much difference as this area is covered by the lap anyway.