Adding Structure to a Bag
The idea for #zwwwave2 came during a sleepless night in June. (To my fellow insomniac sewists: forget counting sheep and try visualizing cutting layouts!) Three months and eight samples later, the design remains relatively unchanged from the original paper prototype, but the challenge has been ensuring that the bag was structural and held its shape. I wanted it to behave like a little leather envelope bag, but made of fabric, so I felt that if the bag was flimsy the success of the design would collapse alongside it.
There are two main methods for creating structure in bags. The first is using a material that is strong enough to function as both the bag’s expression and its structure. A perfect (and perhaps extreme) example of this is the L.L.Bean tote made out of 24oz canvas. I'm pretty sure it would remain upright in 100 mile-per-hour winds. Unfortunately, #zwwave2 has curves and sharp corners that would be impossible to achieve in a heavy-weight fabric. Plus, sourcing a 24oz canvas seems almost as hard as sewing with it. The second method is expressing one material and relying on another hidden layer to provide structure. Playing surgeon on several vintage designer bags has taught me that this method is widespread in bag-making, especially when the bag is constructed from leather. Watch this video to see how leather hides are often split open to laminate a plastic or cardboard interlayer to give it more structure! Similarly, quilted bags like a Vera Bradley, use a foam stabilizer to stiffen otherwise flimsy, outer cotton layers, not unlike putting batting inside a quilt or coat. It’s all a bit dishonest, but satisfying, isn’t it? With little previous knowledge about what’s available, I pursued many options for interlayers and this is what I learned.
This is an overview of the different types of interlinings you may encounter, based on my experience.
INTERFACINGS
Most sewists will be familiar with interfacings: they are a type of fabric interlayer usually fused to the wrong side of fabric to reinforce, stabilize, and stiffen it. It’s for this reason that the #zwwave2 pattern calls for interfacing only if the fabric you've chosen to use is a lighter weight than recommended. A somewhat light and limp canvas, for example, once interfaced, should behave similarly to an oilskin or waxed canvas (the recommended fabrics) which are both intrinsically stiff and structural.
STABILIZERS
A stabilizer is similar in principle to an interfacing but it’s not a fabric, but rather another material designed to give structure to fabric, either temporarily or permanently. (I won’t get into this whole other subset of temporary stabilizers that are cut-away, wash-away, heat-away, etc.!) Like interfacings, bag-making stabilizers are available as either fusible and sew-in, and they’re generally heavier and thicker, and therefore less prevalent in garment sewing.
#ZWWAVE2 SAMPLES
My first three bag samples used various forms of plastic and chipboard. The plastic gave the bag a brittle feeling like the brim of a baseball cap, which is apparently what this product is designed for. Chipboard, or thick and dense cardboard, worked moderately well except for a resilience factor: I worried that the force of opening the front flap repeatedly would create a permanent fold/crease at the magnet. Both were successful in creating structure but I suspect they’d benefit from being laminated between a more durable material like leather.
I will say that while it’s possible to get away with not trimming the seam allowance away when working with interfacings, it’s super important to do so with these stabilizers, otherwise the edges and corners will be either extra bulky or just impossible!
For my next two bag samples, I used a 8.25oz/280 gsm cotton canvas that I double interfaced. This was an experiment to see the results of omitting a stabilizer. The result wasn’t bad by any means but certainly lacked the “I can’t believe it’s not leather” effect I had been going for.
Last but not least, I tried a foam stabilizer for my last two samples. My local sewing store happens to stock byAnnie’s “Soft but Stable”, which was developed specifically for bag-making and lives up to its name. It provides structure without being stiff and it makes opening the front magnetized flap just feel good! It worked perfectly with oilskin but it felt a little more foamy or “crafty” with a thin wool.
“Soft but Stable” can be elusive so my pattern testers have helped me identify alternatives, outlined below. I’ve also assembled a limited quantity of kits which include a zwwave2 portion-sized piece of foam stabilizer, as well as the magnets and ring hardware. They will be available in my shop upon the release of the sewing pattern.
Although I ultimately recommend using a foam stabilizer and following the pattern’s fabric recommendations for the best results, the spirit of this bag is to be as zero / minimal waste as possible. If that means using whatever fabric scraps you have on hand, please do so! If that means sourcing a stabilizer that’s locally available to you, or improvising—one tester used felted wool and another, an old yoga mat, both to great success—do that too!
