Using fusible interfacings made for knit fabrics is a great way to add structure and stability to your knit garments. There are several knit fusibles to choose from and it is important to pick the right type for each project. So I thought I should do a guide on common knit interfacings and how I use them. I’m personally a big fan of using fusible interfacing for knits, especially since I like to add structured details to a lot of my garments, such as collars, buttonholes and pockets. And to put it bluntly, knit interfacings are pretty much a necessity in those instances for a satisfactory result.
Examples of when fusible knit interfacings can be used
- Collars
- Plackets
- Cuffs
- Pockets
- Necklines
- Sleeveless openings
- Facings
- Hems
- Buttonholes and eyelets
2-way stretch fusible interfacing for knits
This is my favourite knit interfacing, and I always buy a lot when I can find it. It often has a chevron type of knit structure and stretches lengthwise, crosswise and diagonally. This one has never caused me any wrinkled or puckered situations. It is fairly light and gives the perfect amount of stability, especially great on medium to heavier knits.
Vliseline H609 is a version of this interfacing (Amazon affiliate link)
Use
- Facings
- Collars
- Cuffs
- Hems
Don’t use
- Button plackets
- Buttonholes and eyelets
- Anything where you want to eliminate stretch
Facing stabilised with the 2-way stretch fusible
1-way stretch fusible interfacing for knits
This is similar to the 2-way fusible in hand and weight. But it only stretches crosswise (and diagonally) and has a slightly firmer hand too. I use this for button plackets, collars and cuffs on medium to heavier knits, where I want to eliminate stretch in only one direction. Also if you cut it on the bias you will also get a fair amount of stretch. Not as failproof as the 2-way chevron and sometimes I feel it doesn’t fuse as well, but that could be me getting a bad batch occasionally.
Use
- Facings
- Collars
- Cuffs
- Button plackets
- Necklines
- Shoulder seams
- Buttonholes and eyelets (on knits that only has 1-way stretch, by placing the non-stretch direction of the fusible in the stretch direction of the fabric you will stop the fabric from stretching in any direction)
- Pocket openings
Don’t use
- On very lightweight knits as it will change the hand and make the fabric rigid. I also don’t like it on hems
Cuffs stabilised with the 1-way stretch fusible
1-way stretch light-weight interfacing for knits
This interfacing is very similar to regular featherweight fusible interfacing. It only stretches crosswise and is so thin that it doesn’t change the hand of the fabric much. Best for interfacing the second, underlying layer, of the fabric as this interfacing is the most likely to be distorted when stretched out a lot, especially on spandex knits. But smaller areas such as buttonholes are usually fine. You can also cut strips on the bias for just a smidgen of stability when needed.
Use
- Facings
- Collars
- Cuffs
- Button plackets
Don’t use
- Eyelets
- Avoid big areas on outer layers of fabrics, especially if the fabric is thin
Buttonhole stabilised with non-woven 1-way stretch. The non-stretch side is placed in the same direction as the buttonhole.
Iron-on bias tape with reinforcement
If you need to stabilise necklines, sleeves openings and other rounded or diagonal edges, but also want to retain some stretch this is the best product among fusibles. The strips are cut on the bias but thanks to a chain stitch in the middle (which also works as a stitch guide) this tape is the perfect combination of stretch and stability.
Use for
- Necklines
- Sleeveless openings
- Shoulder seams (if you want them to stretch a little)
Sports lycra knit neckline stabilised with bias iron-on tape
Brand names
Vlieseline bias stay tape (Amazon affiliate link)
Some suggestions on pressing knit fusible
Use dry heat (unless stated otherwise) and always do a sample. When fusing on synthetic knit fabrics you might need to lower the temperature a bit, otherwise, the fabric might be ruined. Around 10 seconds is enough and let the fused piece set for at least 30 minutes. But I actually like to fuse and leave it until the next day as per an advice I was once given by a very knowledgeable person.
Final thoughts
Hope you found this guide was useful. Of course, there might be more knit fusibles out there, but these are the ones available in Sweden and I assume that it doesn’t differ too much from country to country. And if you are new to using fusibles with knit fabrics I highly recommend that you try it, as they can vastly improve the outcome, especially if you are sewing more structured knit garments.

This post contains Amazon affiliate links, meaning that a commission is earned from qualifying purchases.
20 Comments
COREY
April 13, 2018 at 1:34 amJohanna, I have a few questions for a topic not covered in your book. I am guy, no surprise there and I would like to make up some underwear for myself. The underwear I currently purchase is made by jockey, and its a sports boxer brief, making up a pattern based on a pair if fine, i can do that. What I want to know is what fabric should I use, for comfort, stretch that comes back, easy to wash for example, when i travel i often have to wash my things in the sink/tub in the hotel room, and what kind of elastic do i need for a waistband that won’t roll and is comfortable, that won’t bit into my sides. Further, the fabric has to have moisture wicking properties since sweating and chaffing are very uncomfortable. Thank-you in advance.
Johanna
April 15, 2018 at 1:36 pmHi Corey! My favourite underwear material for the kind of purpose you describe are microfiber knits. It is very soft, almost like cotton but is usually a poly/spandex mix, quick drying and easy to wash. It can be kinda tricky to find sometimes, I have bought mine from underwear notions companies, so that should be the first stop, but I’m sure there are more stores internationally. A quick google search shows me that Jockey uses that fabric too for their undies. I love that material!
Adrianne
April 13, 2018 at 2:20 pmThanks for all the info! I will definitely save this for future reference! For Corey: You should check out Thread Theory. You said you have your own pattern, but they also list sources for materials https://threadtheoryblog.wordpress.com/2014/05/02/looking-for-elastic-for-your-comox-trunks/. Good luck!
Johanna
April 15, 2018 at 1:37 pmAwesome! The Thread Theory is truly doing a great job in an underserved market
Jevonique Edwards
December 29, 2019 at 9:45 pmCan non-stretchy interfacing be used for knit material? For example using pelon interfacing on liverpool knit material?
Phil
March 16, 2019 at 4:54 pmThe standard way to talk about stretch is 2-way (what you call 1-way) and 4-way (what you call 2-way). I know it’s dumb, but that’s how stretch fabrics are described by manufacturers.
Sporty Fleece Jacket | Last Stitch
April 2, 2019 at 4:27 pm[…] If you want to learn more about different fusible interfacing options, you can check out my post about fusible interfacings for stretchy knits. […]
dee
August 11, 2019 at 3:04 amGood Afternoon,
Is the guide for sewing fusible interfacing for sewing knits still available? I am vision impaired and it’s easier when i can touch something and highlight to come back to. Thanks Excellent article/teaching
Video: How To Sew Knits – A Beginner's Guide - The Last Stitch
September 24, 2019 at 8:14 am[…] Interfacing for Knits […]
Sewing Drawstrings on a Leggings waistband: Aila tutorial - The Last Stitch
November 19, 2019 at 9:45 pm[…] Fusible interfacing (it should be thin and only stretch in one direction, see my guide to knit interfacings) […]
Video: 8 Game-Changing Tips for Sewing Knits - The Last Stitch
July 15, 2020 at 12:30 pm[…] Stretch fusible interfacing for knits – a guide […]
8 Great Tools and Notions for Sewing Jeans - The Last Stitch
November 12, 2020 at 2:26 pm[…] Guide to stretchy fusible interfacing […]
Complete Guide To Sewing Knits with a Twin-Needle - The Last Stitch
April 28, 2021 at 10:35 am[…] This is extremely effective when it comes to preventing tunnelling. It will not work as well on synthetic fabrics or on super stretchy Lycra knits, but it’s worth testing out. To learn more, check out our guide to fusible stretch interfacing. […]
Sew a Knit Collar with a Hidden Seam - The Last Stitch
November 12, 2021 at 6:40 pm[…] to give the collar enough stability to make the assembly process relatively easy (check out my guide to stretch interfacing for knits to learn more about this […]
Eivy Sew-Along: Interfacing and Overcasting - The Last Stitch
December 13, 2021 at 7:59 pm[…] To learn more about stretch interfacing and the different types, check out our Complete Guide To Stretch Interfacing For Knits. […]
polly matzinger
January 2, 2022 at 9:29 pmcan you use this kind of fusible fabric on wool? i would like to use it to stabilize some fleeces, straight off the animal, to make “living pelts”: meaning something that looks like a sheepskin, but from which no animal died. the wool holds together fairly well, but it really needs something more stable to hold it all together.while being washed, walked-on etc.
Eivy Sew-Along: How to Sew a Belted Cardigan - The Last Stitch
January 17, 2022 at 10:40 pm[…] This is especially important when working with knits as it will provide stability and sharp corners. But interfacing is great for wovens too, especially the belt. To learn more about interfacing stretchy knit fabrics, see The Complete Guide to Using Fusible Interfacings for Knits. […]
Eivy Sew-Along: Hemming the Cardigan - The Last Stitch
April 5, 2022 at 9:22 am[…] Using stretch interfacing on the hem allowances is a very effective way to prevent wavy, stretched out hems. Just make sure the interfacing is lightweight with some cross-wise stretch and always do a sample before attaching the interfacing to the actual garment. To learn more about fusible stretch interfacing, read the Complete Guide to Stretch Interfacings. […]
Discord
July 24, 2022 at 1:45 amDiscord
Hey check this discord
A Crafty Mix | How to Turn a Sweater Into a Handbag - Easy Sew - A Crafty Mix
November 21, 2022 at 3:46 pm[…] Fusible Interfacing […]