One of the most common things I see when teaching bag making at MHS Studio is interfacing.
Some bags don’t have enough structure. Others have so much interfacing that they become bulky and difficult to sew.
After teaching bag making for the past few years, one thing I’ve learned is that the interfacing listed in a pattern isn’t necessarily a one-size-fits-all solution.
The right interfacing depends mainly on:
- The materials you’re using
- The style and size of the bag
- How structured or slouchy you want the finished bag to be
So today I’m sharing a quick guide to the five interfacings we always keep on hand at MHS Studio and how we use them.
Our 5 Go-To Interfacings
If you’re using quilting cotton for an exterior, accent, or lining, we almost always start with SF101.
For a structured cotton exterior, our favorite combination is:
Cotton + SF101 + Decovil Light
Apply SF101 to the entire cotton piece first, then add Decovil Light for structure.
We usually cut the Decovil Light smaller than the pattern piece so it stays out of the seam allowance. This reduces bulk and gives you cleaner, neater seams.
If you’re using cotton for the lining, we recommend interfacing it with SF101 as well.
Decovil Light – Our Favorite for Structure
If there’s one interfacing we reach for constantly in the studio, it’s Decovil Light.
It gives bags beautiful structure without making them excessively stiff, which is why we use it for so many bag exteriors.
We also use Decovil Light with many of our vinyls and faux leathers. Mora, Rex, Embossed, and Lace Faux Leather are examples of materials we carry that can generally withstand the heat needed to apply interfacing.
Always test a small piece of your vinyl first. Different materials react differently to heat, and you want to make sure yours won’t melt, shrink, or become damaged.
Another option is to apply Decovil Light to the lining pieces instead of the exterior. If you do that, you can usually skip it on the exterior.
Most of the time, one layer of Decovil Light is enough.
There are exceptions. For our Demelza Handbag, for example, we wanted a very sturdy finished bag, so we intentionally used two layers.
Decovil Heavy – For Firm Bases, Wallets & Clutches
Decovil Heavy is one of our favorite ways to add firm, substantial structure where a project really needs it.
For bags, we often use it for the base and gussets rather than throughout the entire bag.
For bags such as the Fancy Tote and Waterlily Tote, we use Decovil Heavy on the entire section at the bottom of the bag. This is especially helpful with larger totes, where the weight of everything you put inside can cause an unsupported bottom to sag or collapse.
We also love Decovil Heavy for bag gussets. It gives the sides and bottom of the bag a sturdy, professional finish and helps the finished bag stand on its own instead of collapsing when it’s empty.
And bag construction isn’t the only place we use it. Decovil Heavy is also one of our favorites for wallets and clutches, where you want a firm, crisp structure. We use it in projects such as our Classic Wallet and Ashley Clutch to help them hold their shape and achieve that polished finish.
Soft & Stable – For Quilted Bags
If you’re quilting the exterior of your bag, Soft & Stable is one of our favorite choices.
It provides structure while giving the quilting beautiful dimension.
We use it for projects such as the AnnaBelle and Konin Bowler Bag.
If you’re quilting vinyl, consider cutting the Soft & Stable smaller than the exterior pattern piece so it stays out of the seam allowance. This makes assembly much easier and helps reduce bulky seams.
Fusible Fleece – For a Softer Finish and Quilted Accents
Not every bag needs to stand perfectly upright!
When we want a softer or more slouchy bag, fusible fleece is a great option. It adds body and softness without creating the firmer structure you get from Decovil.
A great example is the Krystal Convertible Backpack, where fusible fleece gives the bag the softer structure and flexibility that works well with that style.
We also like fusible fleece for quilted accents when we want a little dimension without the additional bulk of Soft & Stable.
What About Linings?
Your lining choice matters too.
Two of our favorite lining materials are Water Resistant Canvas and Bonded Poly, and one of the reasons we love them is that they generally don’t require interfacing.
They already provide more body than quilting cotton and help simplify the construction of the bag.
If you choose quilting cotton for your lining instead, we recommend adding SF101.
The Most Important Tip
Choose your interfacing based on your materials and the finished bag you want, not simply because that’s what the pattern calls for.
A pattern designer has to recommend interfacing based on the materials and structure they used for their sample. Change the exterior from cotton to vinyl, change the lining, quilt the exterior, or decide you want a firmer or softer bag, and your interfacing needs may change too.
Think about the entire combination:
Exterior + Interfacing + Lining + Bag Style + Desired Structure
That’s how we choose interfacing when we’re making samples and teaching projects at MHS Studio.
And remember: more interfacing doesn’t automatically make a better bag. The goal is to add enough structure where you need it while keeping unnecessary bulk out of your seams.
Shop Interfacing
