Friday, September 30, 2016

Zip A Bag Chapter 24: Expanding Tote

Two Zip A Bag posts mere days apart - what is this unorthodox unprocrastination???

I say we run with it while it lasts.

This is one of my absolute favorite bags of this series because it's a serial shapeshifter.

It has so many looks - from the classic trapezoidal tote

which can be carried underarm, granny-purse style,

or slouch-bag style suspended from the zipper ends with either one or both carrying straps.

It can also be slung hip-level with the longer shoulder strap.

And, if you latch those snap hooks at the ends of the zipper 

to the D-rings on the sides of the bag, 

trapezium turns cuboid,

and this little tote moonlights as a boxy traveling case

whose bottom unzips 

for extra volume:

Before we break it down, let me assure you that it is not as time-consuming as it looks.

Unless you're working with print fabric, and you're obsessive about about print alignment at the seams, overlapping pockets, zipper continuity and such.

In which case it might take forever.

But - I promise you - the actual construction is not difficult.

So if you're attempting these techniques for the first time, I'd strongly recommend solid fabric. It's a gaboozleload more forgiving and the bag will come together much more quickly.

Two zipper techniques here:

1  The top (main) zipper

2  The expansion zipper

Let's first learn how to install the main zipper at the top of the bag. 

This bag is really a bigger version of this pouch:

Not kidding. Behold this pouch in side view:

Now see this bag:

Told you.

Since they are the same (even right down to the fabric, for heaven's sake), the zipper at the top is also the same

Which means installing that top zipper is as easy as following this tutorial.

Except that rather than working with two separate side pieces as we did for that fully-open pouch,

we'll be sewing the body as a single piece folded along its vertical midline, similar to the Zippered Marker Pouch, viz

No reason other than minimizing the seamwork - a fold is less bulky than a seam, and when there are as many layers as this bag has, any opportunity to reduce bulk is worth taking.

Here is the lining (partial view) with the zipper at its top edge. The two halves of the zipper tape are basted on either side of the midline.

Lay the outer fabric piece on top of that, RS together, lining up their top edges. Notice:
  1. the outer fabric piece is only a partial piece. Its lower section will be added later as an expansion panel
  2. the stitching line ends about an inch away from the short sides (only one is shown in the photo). We are leaving the outer/lining layers disconnected in this short section so that we can sew the side seams of each layer separately later.

Here are the outer fabric and lining layers pulled apart. The outer layer has a strip of solid contrast fabric along its top edge. This was topstitched on at an earlier stage.

Slowly close the zipper. The WS of the lining and outer layers will come together, giving you an idea of how this bag will look when finished. 

Open the zipper so the fabric layers lie flat once more.
While the lining and outer layers are still separate, finish adding all the details to the lining and outer layer e.g. pockets and strap anchors. 

Working with the outer and lining layers separately, now sew the remaining side seams, pulling the zipper tape out of the way so that their head ends remain unattached and protruding out of the seam. Also leave a gap in the lining's side seam for turning the bag RS out in the final step. Finish the ends of the zipper with fabric tabs and the necessary hardware. I used snap hooks here, and D-rings lower down where the second zipper connects to the main bag.

This is what the bag looks like so far. Notice that the outer layer is significantly shorter than the lining layer (WS shown in the photo below) whose height is the true expanded height of the bag.

We'll be creating the expansion panel next, which extends the outer layer to meet the bottom edge of the lining. This panel is shown folded to half-width in the photo below.

Here it is unfolded to its full width, which exactly matches the circumference of the bag, plus SA. 
The zipper is a regular zipper (it is not necessary to use a separating one), at least 1.25 times as long as the circumference of the bag, plus some extra inches for overlap. The two halves of the zipper will hug the longer sides of the expansion panel.

If this were a circular-base bucket tote, it wouldn't matter where the zipper's tail end is located, which is where the zipper begins its compressing action. However, this tote has a rectangular base and, thus, discernible front, back and side faces and we want this zipper tail to be located centrally on one face, 

so that when fully unzipped, there is some deliberate symmetry to its layout.

Begin by placing the tail end of the zipper along the horizontal midline (red dashed line) and vertical midline (blue dashed line) of one half XZ of the expansion panel. The head ends of the zipper tape will extend beyond the fabric and wrap around again to XYZ when the panel is sewn into a cylinder. This is the layout for the zipper "in the flat".

First sew the short ends of the fabric panel together to create a cylinder, and then baste the zipper on, as shown. Stop some distance away from the head ends - the next two photos show what else needs to be done before completing the attachment of the zipper.

Fold and tuck the head ends toward the SA so that in the finished bag they disappear into the corresponding seams.
Also, see the diagonal-lying SA of the zipper tape in the middle of the panel? That will need to be covered by more fabric.

In the next photo you can see an additional fabric panel cut to fit that V-shaped configuration of the zipper tape. With print fabric, extra care should be taken to align the print of this layer with that of the underlying fabric. Edge-stitch this panel, applique-style, over the exposed zipper tape to enclose it.

You can also see the head ends of the zipper folded toward the SA.

The expansion panel is now complete and ready to be attached to the main bag! 

Here is the expansion panel in action  - as you close the zipper, the upper and lower edges come together, completely enclosing the printed fabric surface and compressing its width to that of the zipper tape alone.

Now attach the expansion panel to the lower edge of the main bag, taking care to avoid stitching through the lining layer underneath. 

This can be done by simply folding the lining layer up and out of the way as shown, which is another reason for assembling the outer and lining layers with their own side seams!

Don't forget to insert any relevant hardware into that zipper seam!

As part of the design, I added a band of vinyl to the lower edge of the expansion panel. The base is then attached to the lower edge of this vinyl band. 

Once the base pieces are attached (the lining base to the lining cylinder and, separately, the outer base to the vinyl band of the outer cylinder), turn the entire bag RS out through the gap in the lining, then hand-stitch that gap shut.

Here is the finished bag, lining side out. When the expansion panel is compressed, the surplus lining fabric simply folds down at the bottom of the bag. 

Here is the outside:

Side view, in un-expanded mode:

So really, for the amount of drama this bag offers, the techniques aren't that hard, are they? Especially if you're easygoing about the print layout and alignment.

I, sadly, am not :(

Coming up next is our very last bag!

It has piping! 

And an offset zippered welt opening (yep - I saved the "worst" for last).


  1. That is an amazing bag! My brain could never even have dreamt up anything like that! And your print-matching... now that's perfectionism at its finest! Way to go, you!!

  2. I've been waiting for this bag since you originally posted pictures of it. I've been fascinated with convertible bags for awhile, especially ones that allow you to make the bag bigger when needed. I also love, love, love the previous bag with the zipper straps. I took a leather coat apart with the idea of making something similar and its still a UFO so your tutorial is something of a godsend. Thank you so much for sharing your creative genius.

  3. Waaw, waaw, and waaw again! Thanks for sharing this idea ;-)

  4. The Bag is wonderful. Nice, Radana

  5. I love it! That expansion zipper is the most epic zipper I have ever seen, I think. Your blog inspired my love of zippers. Thank you!

  6. This is one amazing Rubic's cube of a bag!. How on earth do you think these things up?

  7. Oh.My.Goodness! I never knew how badly I needed this bag in my life. Are you going to sell it in your shop? I'd love one - in solid fabric, please let me know!

    1. Unknown: I am planning to list this in the shop at some point after the series is finished. But I won't be making a new one - it will be this sample shown in this post.

    2. That's great to know! Thank you!

  8. Absolutly love it! I was just wondering why you didn't just put a separating zipper at the bottom to expand it? Wouldn't that be easier to install but still have the same functionality? But if I ever find myself with a non-separating zipper, at least now I have the way to use it =)

    1. Aafke: Excellent question! You can use a separating zipper if you want to. But I don't. Several reasons:
      1 This is a zipper whose zipper tapes are always going to be connected at the tail end; there is no time at which they will ever need to come apart. The zipper, after all, MUST close at the tail end in order for the expansion panel to work. It is true that with a separating zipper, you can connect/engage the retainer box whenever you want to compress that panel, but it's an extra step, and requires you to manually bring the two edges of that panel together. With the zipper permanently in this "V" position, all you need to do is begin zipping, and the panel automatically closes.
      2 Separating zippers tend to be harder to find in stores than regular non-separating zippers. Therefore, this techniques simply makes it easier to introduce an expansion panel without the need for harder-to-find supplies.

      Hope this helps!

    2. Thank you very much for your response. I have both separating and non-separating zippers and I'm happy to have now the information to add them both and be able to choose =)

  9. Absolutely love this bag, it is a marvel of engineering. Fabric is awesome also. Thanks for the tutorial.

  10. where can we purchase this pattern? Can't find it in the patterns for sale. It is fantastic.

  11. You are simply amazing! Beautiful bag! Cute little model. Can't believe your girls are getting so big.

  12. This post just confirmed something that I have been thinking for awhile... you are a genius! Amazing bag!


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