Friday, January 25, 2013

Make A Bag Chapter 4: Design -Layers, Closures and Finishing


Welcome back to the Make A Bag series! So far, we've covered basic structural bag shapes and some typical straps. We mentioned that straps, being an integral part of bag design, affect what the bag pattern will look like when it is drafted. Once you've decided on the design of your bag (size, shape, straps, etc.), you'll need to decide on its layers - how many? What kind? How thick? The layers of a bag will determine how you actually sew the pieces together. Today, we'll be dissecting and analyzing bag layers, broaching bag closures and suggesting some approaches for finishing a bag in the presence or absence of certain layers, particularly the lining. There will be many disparate ideas to cover, so expect it to feel a little "all over the place"!

LAYERS

These are some typical layers of a bag, not all of which are always present:
  • Outer layer 
  • Stabilizer (interfacing)
  • Inserts
  • Lining
Let's break them down individually.

1  Outer Layer
This is the main bag, the part that people actually see. In an unlined bag, this is the entire bag. Now, in garment sewing, the garment is often left unlined, especially if it is a casual garment or one in which thermal insulation is not important. In use (i.e. being worn), only the outside of a garment is visible; nobody needs to see its underside. So it is common for garment seams to be serged and left exposed . Bags, however, subject their inner surfaces to scrutiny every time the bag is opened to access its contents. A lined bag provides a very neat and finished view of these inner surfaces. An unlined bag doesn't - it has seam allowances and bottom-stitching, for instance. We can't do much about the bottom-stitching but we are obliged to finish those exposed seam allowances, both for strength (fraying edges are weak edges) and aesthetic appeal. Some ways to finish the seam allowances on the WS of an unlined bag are
  • Ignore them completely - possible for fabrics that don't fray, like felt, fleece, nylon, leather, vinyl.
  • Pink, serge or zig-zag them. If you're making a tote with your kid, serged edges are perfect. And there are many occasions when, to save time, I've mass-produced light carrying pouches with serged seam allowances. However, if we're making a bag that is intended to bear substantial weight or that we're planning to sell for more than, say, the cost of a Happy Meal, maybe the bar needs to be set a little higher. See next few points -
  • French seams or fell seams. I will use this method whenever I can.  Sometimes I even use these externally on lined bags, for texture. You get to see this later in this post. These aren't suitable for all fabrics, though -some really thick fabrics (like packcloth) don't allow this. 
  • Bind the SA with tape (twill tape is common) or bias tape, or just random strips of fabric. Sometimes, this is even used in lined bags in which the outer bag and the lining are sewed together as a single layer, leaving exposed SA on the inside of the bag. This seems to be the method of choice in commercial bags e.g. backpacks and others with zippered openings. See picture below:


2  Stabilizers
Also known in some circles as interfacing. Stabilizers are so called because they um.. stabilize the fabric i.e they make fabric stiffer, stronger or less likely to rip, shear or stretch in any particular direction. Many materials can be used as stabilizers; some are commercially-prepared stabilizers, while others are just other fabrics found in your stash that have a more suitable weight than the one you are trying to stabilize.

Here are some materials I've used as stabilizers in my bags:

Some notes:
  • Nylon packcloth is just lovely. It comes in many weights. Some are even coated impervious on one side, making it a naturally waterproof sew-in stabilizer.
  • Those crib mattress protectors are my best-kept stabilizing secret. They are the best ever stabilizers for fabric backpacks - just the right puffiness, thickness and stiffness and with a middle waterproof layer, besides. 
  • I use canvas/twill as a sew-in stabilizer. It's soft in a way that commercial stabilizers are not, while still lending a nice weight to the fabric it stabilizes. Sometimes I use it as a non-batting (i.e. non-puffy) alternative for quilting, like in this bag.
  • Commercial interfacing - here's what they might look like on bolts:

These are the two kinds I use a lot- 
  • heavy weight sew in stabilizer, which is slightly puffy and which is sewn to the SA on the WS of the fabric pieces. It's lighter than canvas. 
  • craft-fuse, which is fusible (i.e. iron-on) interfacing that is craft-weight. Craft-weight= stiff. Not for garments, unless it's a robot suit. I know that lots of people hate craft fuse. I hate it, too, and for the same reasons: it wrinkles, it's crumply, it feels unnatural etc. However, I also love it because it makes gloriously stiff straps. I will share two tips for preventing wrinkling with this heavy fusible stuff:
  1. Only use it with fabrics that are heavier than it e.g. duckcloth, canvas, some homedecs. Never use it on regular cotton, satin, flannel, gingham, etc. If you're needing something as heavy as craft fuse to stiffen something as floppy as quilting cotton, you're clearly using the wrong weight fabric for your project. Go shopping for something heavier. All that said, I do that, too - love a designer print in quilting cotton weight and try to stiffen it to death. It's hard to fight a good print. See next point. 
  2. If you insist on sewing with a lightweight fabric and need it stiff, you can still use craft fuse (or any heavy fusible interfacing). Just don't fuse it to that lightweight fabric. Cut another piece of heavy material (e.g. some canvas, batting or even sew-in interfacing) and iron the craft-fuse to that. Then sew that composite layer to the WS of your lovely lightweight fabric. That way you get all the stiffness you want but without the wrinkling.

3  Inserts
are additional materials that I include for special functions. Some of these are:
  • Heat-insulation and deflection inserts (Therma-flec, Insul-bright) etc.
  • Waterproof inserts
  • Base inserts - for making rigid bases of bags without having to resort to cardboard. You all know I love cardboard, but it doesn't survive washing. I've used template plastic (very light and flexible), plastic canvas (medium flexibility) and flexible cutting boards (much heavier).


4 Lining

Forgive me for climbing onto my soapbox now but I really like lining my bags. It isn't just for aesthetics. Remember that once you introduce interfacing or inserts, they are visible from the inside of a bag, so you will need to conceal them under a lining or else flash them to the world each time you reach in for your wallet or breath mints. The same goes for anything - like the pouch of a welt pocket, for instance - that visibly protrudes from the back of the outer layer into the bag cavity. Let me share some other advantages of lining a bag:
  • robustness and structure
  • reversibility
  • aesthetics
  • concealing the backside of stitches
  • adding pockets
  • possibility of interfacing
  • possibility of base inserts
  • installation of hardware
  • possibility of waterproof inserts
  • possibility of heat-resisting inserts
  • natural casings and channels between layers, for drawstrings etc.

Of course, there are instances when I will choose to leave a bag unlined. Most common are:
  • I'm mass-producing them for a party and I don't want to take the time to cut double of everything.
  • The fabric is already very heavy and the bag is relatively featureless, so that it neither requires interfacing nor the concealment of innards of pockets, for example.
  • I was already planning to finish the seams externally (e.g. bound or french seams) for some aesthetic value.

FINISHING A BAG
The presence of absence of a lining greatly affects how the bag pieces are assembled and how the bag is finished. 

Without a lining, you'd have to finish the seam allowances. See Section 1 (Outer Layer) above for some ways to do this.  And while we're on the topic of finishing SAs, let's discuss french seams:

They're quite popular on bags because they reinforce and emphasize the edges of the bag and square out its overall shape. 

This is a fold-up shopping bag I made. See the blue arrows indicating those side seams that emphasize the angularity of the bag. 

These are actually bound seams. Externally bound by a strip of the same fabric, to be precise. 

Bound seams -internal and external - are not limited to unlined bags. You can also do them in lined bags - just sew the lining and outer fabric together as a single layer and then bind the SA like the bag above. Remember this earlier photo?

But those aren't french seams -they're just bound seams. 

Here's a diaper bag I made years ago. Those are the french seams that the blue arrows are pointing at.

I dug this bag out of abandonment (it's never been used) to show you how I do french seams in a bag with a lining, when all the fabrics involved are thick and bulky.

See? Self-explanatory. Make the lining smaller than the outer bag. Or, more specifically, make the lining have regular flat seams and let the outer bag have extra allowance that ends up being pinched like a pleat to make that french seam.

The process of building up a bag from its individual pieces continues until only one, final seam remains. This is often, but not always, the seam at the top/opening of the bag. There are two common ways to finish this last part of a bag:

  1. Turn the whole bag RS out through a hole in the lining (TTWBRSOTAHITL) 
  2. Topstitch the rims of the bag and its lining together.

I wanted to show you those external french seam pictures in support of my next statement: I don't do the TTWBRSOTAHITL deal if I can help it. It's like the Whole-Bag equivalent of the Slow Death by Chopstick thing (see this post for explanation) that I don't do with straps. If you aren't familiar with TTWBRSOTAHITL, it's that method that involves a bag and its lining being sewn together at their rims, inside out, to make that top seam. Then everything is turned RS out through a hole in the lining and maybe that top seam is additionally topstitched on the RS. And maybe (if the sewist is not lazy) that hole in the lining is hand-stitched closed, or else it's just machine-run-over. Quite a few bags have been made that way on sewing blogs. It is not an unorthodox method, by the way. However, if you use thick fabrics, interfacing and/or inserts, TTWBRSOTAHITL just isn't practical. Interfacing crumples, canvas gets stuck and frays, plus you spend an inordinate amount of time ironing and re-ironing the bag each time you pull it through the hole in the seam. It can be quite the nightmare. Plus - and I'm finally getting to the point - you can't fully do raised seam finishes like that external french seam in the picture above. 

My first choice method for finishing lined bags is topstitching their openings together. In the picture below, the outer bag (green fabric) and lining (white fabric) are individually complete and ready to be sewn together at their rims. The SA of their rims are folded to their WS, the rims pinned (or hand-held) together 

and topstitched (or edge-stitched). Here is the lining side of the bag

and here is the outside of the bag.

While the topstitching method is my first choice, there are times when I will choose TTWBRSOTAHITL over the topstitching method to finish a bag, for example:

  • When there's piping involved at that opening seam.
  • When that opening seam is curved. 
We will be seeing both situations in later chapters.


CLOSURES
To round up bag design, we must look at the closures of bags. Some bags don't have a closure- they are just left open at their tops. Those aside, there is no limit to the ways you can close a bag (and these are just a few):


Ties;

Elastic;

Drawstring;

Purse frame that squeezes; 

or twists;

Looped straps;

Zippers;

Buckles, snap hooks and other hardware;

Flap, 
which may be full

or partial

and which may or may not have a device for fastening it shut. Here are some common ones:


So: shape, straps, layers, closures, finishing - basic elements for consideration when designing a bag. We're ready to start reconstructing the different kinds of bags now but before that, we'll be spending a little time on reversibility. I was going to include it in this post because of its relationship with layers but I think it deserves its own chapter where I can analyze it to death. That's coming up next!

25 comments:

  1. Very useful information! Thanks

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  2. Really enjoying the series! I too try to use the topstitch method to finish a bag vs the through the hole way and haven't seen many other blog/tutorals that do.

    looking forward to the rest!

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  3. While sewing a bag to its lining at the opening is probably less of a headache, I've found that turning a bag right-side out really isn't a problem if the hole is sufficiently large. If you only leave yourself 3", then yes, it's going to be a wrinkled mess and you're probably going to have broken stitches no matter how many times you backstitched at the edge of the opening (or possibly even rip your fabric, if you were really diligent about backstitching). I leave 6-8" and really don't have a problem.

    As I think about this more, I think the reason I don't have an issue is that I try to leave a hole that's larger than the narrowest dimension of the bag. You're not going to get serious crumpling if it's not being compressed in all directions.

    As far as interfacing goes, a while back I switched to using Pellon's Decor-Bond instead of Craft-Fuse. I do prefer the finished product over Craft-Fuse, but the fact that Decor-Bond is 40" wide and folded makes cutting things out much faster and was probably the deciding factor.

    Have you ever used fleece bias tape? I made a laptop sleeve a little while back using fleece tape to encase the seams. Loved the stuff. It was so easy to work with.

    And for anyone reading the comments, if you're new to a closure like magnetic snaps that involve cutting the fabric to install, I like installing them before assembling the bag. But if you're going to do that, be really, really sure you're installing them on the correct pieces. You don't want to learn this one the hard way.

    (By the way, I consider myself more or less expert at bag making, but I've learned a few things already in this series! So thanks for that. :) )

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    1. Thanks for all the info, Anna, and for sharing your methods! I've considered Decor Bond, too, like the one time when the shop was out of Craft Fuse. DB is quite a bit more expensive, especially when buying by the bolt the way I do. I try to avoid using fusible whenever I can - I'd rather use packcloth to stabilize or a really good weight fabric to start. But sometimes a person just has to cave and use a fusible. Since I've never actually bought DB, I hadn't realized it was double the width of CF. Whoa! That IS a good reason to buy DB, especially if one regularly uses large pieces of fusible for bags (I don't). So thanks for sharing that useful fact!

      No, I've never tried fleece bias tape. Do you make it yourself or do you mean the sort you buy on cards at the fabric store? I've seen them before but always thought they were for baby blankets. Such a one-track-mind way of thinking, I know :( I've learnt something new today!

      I hear you about the magnetic snaps and cutting holes. Ugh. Been there. For that reason (and aesthetics), I use the invisible magnetic snaps whenever I can rather than the regular ones. They're stronger and install by sewing within the inner layers (interfacing and such) of the bag, so no holes. Plus they feel like magic. Do people really install magnetic snaps AFTER the bag is sewn up? Really? I never knew. Is this common? How does one do that without exposing the backside of the snap? Blows my mind. I'd always thought one should install magnetic snaps (and purse feet) before assembling the bag, so the backsides can be then concealed within the lining layers. Do you mean they actually leave the backsides exposed inside the bag? Wow. Um.

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    2. Ack! No, no, no, I meant before assembling the lining! Wow, did I misspeak there. I prefer to install them on a piece that hasn't been attached to anything (but the fusible) because it's just easier to manage that way. I'll have to look into the invisible snaps, though. I'd prefer the appearance of no hardware.

      Fleece bias tape is the packaged stuff, yes. I found it really useful for covering up the seams in a heavily padded laptop sleeve. The stretch of the fleece combined with the stretch from the bias made it really easy to cover the thick seam allowance.

      And finally, which I perhaps should have mentioned first, Decor Bond appears to be about twice the price of Craft Fuse because you get twice the interfacing. Plus half the cutting. In reality they're the same price.

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    3. trish
      thanks so much this has really helped me i have been making everything the hard way again thanks so much

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  4. I am really loving this series! I have already learned so much. Can't wait for the next chapter!

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  5. Dear LiEr,
    Thank you for your generosity on sharing ALL this! I really appreciate the time you put into it...
    Have a great weekend!!
    xo
    Bea

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  6. That was super informative! I love this blog.
    I'm guilty of using the TTWBRSOTAHITL method on a lot of bags. Once I made the mistake of doing that to a knit material and it got really stretched out.

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    1. Sydney: Don't feel guilty! I use it, too. I think many people like this method because it guarantees that the circumferences of the two rims (outer bag and lining) will match. The topstitching method works only if the circumferences match already and one hasn't, say, stretched during handling. I try to measure the final circumferences before I topstitch, to rule out that headache. But sometimes I get unmatching circumferences regardless, (i.e. if one fabric has more give than the other), in which case I have to ease the circumferences to match so I don't end up with pleats (ugh).

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  7. I've always wondered why the "TTWBRSOTAHITL" method didn't have an official name...

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  8. Oh how I love this series!
    Thank you so much LiEr for all the time you spent on it!
    I already learned so much!

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  9. I am raising my hand in the "TTWBRSOTAHITL" group. I thought that "TTWBRSOTAHITL" was great. But, I did always end up with wrinkles and they were wrinkles that did not want to press out! Thank you so very much for the time you are taking with this series. I have been making purses for over 30 years....but I am learning so many useful things from you that will surely have my next bag looking great and now wrinkle free!
    Deb

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  10. I have two questions, forgive me if they are lame, I'm still a beginner and several of these techniques/elements are new to me. You mentioned the inserts can be machine washed can they be dried too, or just hang dry? On the french seam diaper bag, I am not clear how it was top stitched. Did you insert the lining and just top stitch up to where the french seam starts?

    Thank you so much for this series, I cannot tell you how many light bulbs have gone off in my head. My mind is swirling with ideas!

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    1. Kerry: No, not lame at all! And I'm happy to answer them -

      Inserts: It depends on the inserts. I would probably hand wash and hang-dry bags with the softer inserts (e.g. the template plastic) if the bags also are made of soft fabric. If they are made of much heavier fabric (e.g. duckcloth), I'd say the heavy fabric will provide enough of a cushion against the squeezing and twisting of the washing machine. The heavier inserts (cutting board, for instance) should be okay to machine wash and dry. I think (but I haven't tried yet myself) that the issue is more the twisting/crushing danger from the washer than the melting of the plastic in the dryer. Then again, I've never dried template plastic in a dryer, so if anyone has tried it, do share!

      French seams: Yes, I topstitched (and backstitched) around the french seam in that case and left the french seam alone to continue standing out.

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  11. everything is very nice!!!:):)

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  12. I had a question about stabilizers. Do you ever use light weight fusible interfacing like you would use in garments? Could it be ironed onto the back side of lighter quilting weight cottons to bring them up to home decor weight? If so, do you think it would stay fused though lots of handling/washing? I guess it stays fused to clothing...

    I never knew there were invisible magnetic closures! I need to spend more time in the notions aisle! :) Would they work for reversible bags? Or would they end up repelling themselves? Maybe a double layer?

    Thank you so much for these posts!!! I have a bag all drawn out that I am going to make.

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  13. WOW!Thank you for posting and sharing. This is a treasure of good information!!!

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  14. I was wondering if using canvas as a bag stabilizer, does the outer fabric have to be equal or heavier than the canvas? In my case I want to reinforce medium weight linen. Thanks for all the information :D

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    1. Jessica: Only for fusible interfacing. If it's sew-in, it doesn't matter which fabric is heavier than which.

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  15. Good Morning -Which bag style would you recommend to carry a Feather Weight machine and case, Thank you , Cindy ... nrsi2000@aol.com

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  16. Dear Ikat,
    I am so glad I found your site: I was always looking for a "special" bagpattern, but once its too big, some stripes don´t please me, a second inlay-bag ist missing.... an so on. But I am not as talented, as you are. So I finished some bags, not yet "the one".
    Right now, I arrive on chapter 4, I have an idea of realizing my bag. When I finished your classes I need time to design my bag. When its sewed, I let you know.
    Thank you so much for explainig the theory, this ist what realy helps in sewing!
    Bye for now
    Elektra

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  17. I have a question about lining. I always sew bigger seams in my lining so that it fits better inside the bag, but too often I still have baggy linings what just seem too big inside. Do you have a method or technique or set system for measuring and cutting your lining to fit perfectly?
    I'm really interested in your answer because you have so many ideas for construction that I hadn't considered before. I've been making bags for years, but getting just the right the fit of the linings confounds me.

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    1. Unknown: I do not have a special technique for fitting lining layers, at least not one that I would consider a "secret tip" type of technique. I always make my lining layers
      (i) exactly the same size as the outer bag layer to begin with, although I measure the openings of both layers just before I sew them together. Sometimes this requires taking in an eighth of an inch in the lining's circumference and sometimes not.
      (ii) in as robust a fabric as I can. This means homedec rather than quilting cotton. Or else I stabilize it with a sew-in interfacing. The softer the fabric, the more it will sag.

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  18. Hello! First THANK YOU sooooo much for this series! You have helped me in so many ways!!! I was wondering if you were by chance planning on doing a Zipper closure series or something of the sort? You have an upfront no holds bar type of teaching style that not only speaks to my inner bag maker, it screams to it lol. Your tips and thoughts are streamlined and perfect for my brain to comprehend. I can guarantee that you would change at least my life in a great way if you chose to do something on different types of zippers in bags! Thanks! Lauren

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Thank you for talking to me! If you have a question, I might reply to it here in the comments or in an email.