The Interfacing That Makes Fabric Behave
Hey everyone. Corey here. If you sew garments, bags, or t-shirt quilts, this is the bolt that quietly makes the whole project work. Pellon SF101 Shape-Flex is a woven cotton fusible interfacing. You iron it to the wrong side of your fabric, and that fabric suddenly has body. Collars stand up. Cuffs stay crisp. Stretchy t-shirt knits stop stretching and sew like quilting cotton. This guide covers what SF101 is, the ten jobs it does best, what it pairs with, how to care for it, and the questions we hear most at the shop. It comes on a 20 inch by 10 yard bolt in white, so one bolt covers a whole lot of sewing. New to interfacing altogether? Start with our Pellon interfacing and stabilizers guide. For fabric too delicate for SF101, see the Pellon 911FF featherweight guide. And when a bag needs to stand up on its own, that is foam territory — read the Pellon FF78F1 Flex-Foam guide.
What Is the Pellon SF101 Shape-Flex?
SF101 Shape-Flex is an all-purpose woven fusible interfacing made from 100% cotton. That word "woven" matters, y'all. A non-woven interfacing is pressed fibers, and it can feel stiff and papery. SF101 is woven on a loom just like fabric, so it moves with your fabric and keeps a clean, natural hand. It firms things up without turning your shirt into cardboard.
One side carries the fusible adhesive — little slightly rough, bumpy dots you can feel with your fingertips. That dotted side goes against the wrong side of your fabric. Press it with a hot, dry iron and firm pressure for several seconds, section by section, and the bond is permanent. Pellon rates it light to medium weight, which is the sweet spot for most garment and quilting-cotton work.
This listing is the bolt: 20 inches wide and a full 10 yards long. That is 30 feet of interfacing on one roll. A single shirt takes well under a yard for collar, cuffs, facings, and placket. A t-shirt quilt with 20 blocks takes a few yards. So one bolt handles a season of projects, and it costs far less per yard than buying small packages one at a time. If you sew regularly, the bolt is the way to buy it. We're not reinventing the wheel here — every experienced sewist keeps a bolt of this within reach of the iron.
Top 10 Uses for Pellon SF101 Shape-Flex
- T-Shirt Quilts -- The classic SF101 job. Fuse it to the back of each t-shirt block and the stretchy knit behaves like quilting cotton. No wavy seams, no stretched blocks.
- Shirt Collars -- Fuse the collar and collar band so points stay sharp through washing after washing.
- Cuffs and Sleeve Plackets -- Crisp cuffs that fold where you want them to fold, every time.
- Facings -- Neckline and armhole facings lie flat against the body instead of rolling and peeking out.
- Waistbands -- Skirts and pants waistbands keep their shape and stop folding over at the crease.
- Pockets -- Back patch pockets so they hold their shape, and support pocket openings that take daily wear.
- Bag Bodies and Flaps -- Gives tote bags, pouches, and purse flaps real body while the bag still feels like fabric in your hand.
- Embroidery Backing -- Stabilizes fabric behind machine embroidery so stitches sit clean instead of puckering the ground fabric.
- Appliqué Support -- Firms up the background fabric so appliqué edges stitch down smooth and flat.
- Dress Bodices and Yokes -- Adds gentle structure to bodices, yokes, and button bands on dresses and blouses.
What It Pairs Well With
Thread
SF101 adds no special thread demands. Sew your fused pieces with the same quality all-purpose or quilting thread you would use on the fabric itself. Because the woven interfacing moves with the cloth, seams stay flexible and your regular stitch length works fine. No changes needed at the machine.
Fabric
Pellon designs SF101 for light to medium woven and knit fabrics. The product page names oxford cloth, chambray, gingham, flannel, quilting cotton, and cotton-poly blends, and every one of those is a great match. Quilting cotton is the daily driver in our shop. T-shirt jersey is the other big one — that is exactly the fabric SF101 tames for memory quilts.
Backing
Think of SF101 as the first layer of structure. When a project needs more, layer up: SF101 on the fabric, then a fleece for softness or a foam for stand-up shape. In bags, many makers fuse SF101 to the lining and let the outer fabric carry a fleece or foam. Completely up to you — test on a scrap and see which hand you like.
Care and Washing
Once SF101 is fused, it is machine washable and holds its bond through normal laundering. Garments and quilts made with it go through the wash like any other cotton project. Two habits keep the bond strong for years. First, fuse it right the first time: hot, dry iron, firm pressure, several seconds per section, and let each section cool before you move the piece. Second, press — do not slide. Lift the iron and set it down on the next section. Sliding a hot iron across unfused interfacing shifts it, and a shifted piece wrinkles where you cannot fix it. Slow down right there and you will never fight bubbles. And if a corner ever lifts after washing, just press it again with the hot iron. The adhesive reactivates and bonds right back down. Just like that.
Frequently Asked Questions
Which side is the fusible side?
The fusible side is the one with the slightly rough, bumpy adhesive dots. Run your fingertips across both sides and you will feel the difference right away. Place the dotted side against the wrong side of your fabric and press with a hot iron to bond.
What fabrics is SF101 best for?
Light to medium woven and knit fabrics. Pellon names oxford cloth, chambray, gingham, flannel, quilting cotton, and cotton-poly blends. In our shop it earns its keep on quilting cotton and t-shirt knits more than anything else.
Is SF101 washable?
Yes. Once fused, Shape-Flex is machine washable and holds its bond through normal laundering. That is one reason it beats sew-in interfacing for garments and quilts that will actually get used and washed.
How do I apply SF101?
Cut it to size, place the adhesive side down on the wrong side of your fabric, and fuse with a hot, dry iron using firm pressure for several seconds across the whole piece. Work in sections, lift and press, and let it cool before handling. A test fuse on a scrap first is always a good idea — take your time, it is not a race.
Can I use SF101 for a t-shirt quilt?
Absolutely — it is the interfacing most t-shirt quilters reach for, including us. Fuse a piece behind every shirt block before you trim it to size. The knit stops stretching, the blocks come out square, and the whole quilt sews together like a regular cotton quilt. If I can do this, y'all can do it.
What is the difference between SF101 and a non-woven interfacing?
SF101 is woven 100% cotton, so it drapes and moves like fabric and never feels papery. Non-woven interfacings are pressed fiber sheets. They work, and some are lighter for delicate fabrics, but they can feel stiffer and can crease. For most garment parts, bags, and t-shirt quilts, the woven hand of SF101 is the one folks prefer.
Shop the Pellon SF101 Shape-Flex 20 Inch Bolt
We stock SF101 by the 20 inch by 10 yard bolt because that is how our customers actually use it — a bolt on the shelf means collar, cuff, bag, and t-shirt quilt emergencies are already handled. Thanks for reading, y'all. We'll see you next time. Bye.
Shop Now: Pellon SF101 Shape-Flex Cotton Woven Fusible Interfacing 20" x 10 Yard Bolt, White
