Do Knit Fabrics Have a Bias?

Tiramisu- a dress cut (mostly) on the bias

When this question comes up in classes, I used to reply “The short answer is, no.  Knit fabrics behave differently to wovens, only wovens have a true bias.”  That’s not inaccurate, as far as it goes. The long answer is a little more nuanced, and it’s taken me the better part of a year to satisfy myself about whether knit fabrics have a “bias” grain or not.  I think they do, even though the nature of the fabric is different than a regular woven.

I run a few regular searches on google, to find any new blog or forum posts on the topic.  I never found much information online or off about whether knits have a bias grain.  Opinion varies widely on the topic of knit bias, so I knew I would need to experiment on my own to find an answer that satisfied me.
Earlier this year, I made the Bow Tie Tee, a hack of the Blank Canvas Tee and also available as a pdf pattern.  The jersey I chose to use is a relatively beefy cotton t-shirting with moderate stretch.  It’s pretty stable, a good place to start playing with knit grainlines.  When I worked with the pattern, I didn’t approach it as a “woven” or a “knit” pattern, but as a kind of hybrid.  For most woven patterns, you want at least an inch or two of wearing ease to allow you to move and laugh and jump around.  Most knit patterns tend to have “negative” ease, which means the fabric is cut smaller than the body’s measurements so the fabric will stretch and cling to the body.  For the Bow Tie Tee, I worked with 0 ease- neither extra fabric like a woven, nor “negative” ease like a knit.

I did this because I wanted to play with stripes.  Why else?  The front yoke is cut with horizontal stripes, and the stretch runs the direction it should in a typical knit pattern- that is, the stretch lies around the body.  For the lower front piece, I turned the fabric on its side.  I wasn’t sure this would work, because it’s not usually the way knit fabric is used.  Turns out, it works just fine- probably because I only did this on one section of the garment, not the entire shirt.  This is one of my favorite tops, I’ve been wearing it for months now and I find no problem with the cut or the grain.  It doesn’t bind or ride up, in fact when I put on this shirt I cease to remember I’m wearing clothes.  That’s always my aim.

The back uses another kind of grain altogether- a “bias” grain.  I did this because I have an undying love of back interest and chevron stripes.  Again, I had no idea if this would work because it’s not usually done, but it turned out well.  I noticed that the back seems to have a different kind of “give” and “hug” than a regular knit top.  When I wear the shirt backwards for a plain v-neck front (this works well!), I notice the fabric molds and skims over my bust and waist in a pleasing way.

front, “Lamington,” a work in progress

I tried a similar back bias treatment when working up samples for another upcoming pattern.  (I make and wear samples extensively before working them into a full multi-sized pattern.) This time, the front is quite plain with the stretch running around the body as it would on a normal knit pattern.

I left this one unhemmed to see the effect of the CB downward “growth” more clearly.  You can see that the back has indeed grown longer than the front, and as it stretches downward it gently pulls the side seam to the back.  This is quite clear when I lay the garment out flat, but when I put it on my body fills the shirt and the seams lie where they should.  The back “bias” pieces behave almost exactly the way I would expect a woven bias cut to behave, but with the knit fabric the bias effect is somewhat more pronounced.  Interesting!

The stripes show you clearly that the side seam is cut on the “straight” of grain, and the CF is “bias.”

I took it to the next level with my samples of the Tiramisu dress.  The skirt is cut with the straight of grain at the side and a “bias” seam at the center front and back.  When I first started playing with this concept, I had no idea if it would work in a knit.  I know that “straight” sides and “bias” CF and CB seams works to make a very flattering silhouette in a woven, and I was keen to try on a knit.

thats some good rippling…  The jersey is one of those “modern” jerseys that stays wrinkled… Not sure I love the effect… But I do love this dress.

I’m happy to say it does work quite well on knit fabrics.  I’ve tested it on rather light weight (striped version), medium weight (several muslins), and even a double-layered jersey (red version) to see how the fabric behaves when treated in this manner.  I couldn’t be more pleased with the gentle rippling effect, though I have discovered that a knit bias dress should be hung unhemmed overnight so it can “settle” the same as a woven.

Tiramisu front bodice piece

The bodice for Tiramisu was also interesting.  I liked the stripe placement on a similar woven dress (1950’s pattern I made for Mother’s Day) and hoped it would work for a knit.  It does.  However, I discovered that due to the way the stretch lies on the body (nearly vertical) and the weight of the skirt, the top bodice section tends to stretch.

Made of a heavy weight double layered jersey, works quite well.

Further, I discovered that it’s more or less a standard amount of stretching regardless of the weight of the fabric used.  Lighter fabrics usually stretch more than heavy ones, but the lighter dresses don’t weigh as much as the heavier ones, so it seems to come out even.  In this case, we’re working with the nature of the fabric (stretch), the weight of the fabric, and gravity.

This means that for the underbust seam to lie under the bust, the pattern itself must be quite a bit shorter that the shoulder-to-underbust raw measurement.  If I hold the upper bodice pattern piece up to my own body, it doesn’t seem like it will work.  However, comprehensive testing and understanding how the fabric will behave has shown me how to produce a consistent result.

I also use a carefully-calibrated piece of neck binding to help “snug up” the neck opening to prevent tumbling out of the dress.  I hate having to think about my clothes after I put them on, especially having to worry about that particular issue.  The short binding works well for keeping the neckline in shape without using another kind of stabilizer.  The binding itself is cut on the cross-grain (without much stretch) and about 3/4″ shorter than my neckline opening.  I eased it in, and the result is solid and light.

I have satisfied myself that knit does have a “bias.”  While the nature and structure of a knit fabric is quite different than a woven, I can not deny that knit fabrics behave differently on the body (and with a pattern) when cut on the bias than when cut “straight.”  Furthermore, I think that when a knit is cut on the “bias,” it behaves in much the same way as a woven bias, but more so.

What do you think? Have you ever experimented with knit bias?  Do you know of a great blog post, article, or book on the subject?  I haven’t really found much that was helpful, just a handful of forum postings and a few about.com pages that rambled about knit fabrics.  I’d be quite happy to hear any and all thoughts on this!

(Also… I have some fun sewing for Stephen coming up… I made him some long-sleeved linen work shirts years ago, he gets compliments from the other ecologists whenever he wears them and has requested a few more!  Cool.  I’m planning to use Negroni, I’ve been dying to make it up!  And Lila could use a few new pieces, I’m designing some girlie versions of my ladies’ stuff to try on her.  Should be fun!)


35 comments

  1. This is very interesting and I am fascinated to hear the bias stretch is more or less standard across the various weights of knit fabric you tested out. BTW the fact that each test garment looks fab and are forget-you-are-wearing-them comfy is rather a bonus.

    I was wondering how the bow tie T hack would stand up to regular wearing and washings. Very interesting indeed.

    One question about the binding for the neck – did you apply it from bodice front all the way around to the bodice front cross-over? I’m assuming yes… Oh and cute seal pup :o

    • It’s not just the stretch inherent to the structure of the fabric, it’s also the weight and gravity… Gravity is constant… The lighter skirt doesn’t weigh as much, but the lighter fabric has more inherent stretch… The heavier fabric has much less stretch, but the weight of the skirt makes the bodice creep down.

      It’s a really interesting effect, and I used that knowledge in the pattern making… I’ve been wearing my Tiras for about 4-6 weeks now, and they’re holding up quite well to abuse. I get cranky when they’re dirty and I have to wear something else.

      Bow Tie has been quite good, one of my favorite makes from earlier this year. The neckline is a trifle low, but it’s not bad. Just not the depth I’d usually wear…

      I think you mean the binding on the dress? Yes, it’s one piece across the front and the back neck. With notches for snugging up..

  2. Did you get your striped jersey for Tiramisu from The Fabric Store? I think I bought the exact same fabric yesterday in Melbourne. Very interesting to see how it makes up. It is quite crinkly isn’t it. I was going to make an oversized tee and play with some chevron effects.

    • I did get the striped gray jersey from the Fabric Store…. Their stock is head and shoulders above others in Brisbane for wearability and selection, I don’t go much of anywhere else for apparel fabric. :) It’s kind of a b*tch fabric to work with, likes to curl and stay wrinkled. But I’m pretty fond of the final dress, and the fabric washes well. Would love to see your shirt when you’re finished… :)

  3. Steph I love your dissections of fabric properties like this. And the ‘Lamington’ (love the name) – that’s looking fabulous, I love the neckline at the front. Any chance of a back option that’s more in keeping with the front??

    • Aw thanks! This one will have a pair of moderately wide-leg jeans/trousers with it, I’m just refining the sizing system… I have every intention of making patterns with a little potential for quirk, as well as an “escape hatch” to make the cut plainer. So yes, it’ll have the chevron back or a plain one, I love this cut.. Its based on a 30’s knitting pattern for a top I found… Anyway, enough about that, I might as well just post all about it right now.. ;)

  4. There are patterns for hand-knits (neckties and scarves esp.) that call for knitting “on the bias.” The fabrics do behave differently than those knitted up “as usual.” It does not surprise me that machine-knitted yardage also has a bias.

    • Yes, also shawls and washcloths, right? I looked into that a bit, but it was basically about constructing “bias” knit fabric rather than cutting an existing fabric in a certain way… Quite interesting, I really want to play with knitting bias sometime, too. Not enough hours in the day, right?

  5. The patterns look great so far!
    I’ve never thought much about knit bias. I do have a dress that crosses over in the front similar to your Tiramisu dress, but never noticed anything too weird going on. That might also be because i left it unhemmed so I wouldn’t notice any growth anyways.

    • Thanks Molly… Most of my work for Tiramisu is over, the pattern is with the digitizer and my artists and I are working on the envelope and instructions…

      I think most dresses like this would be cut in the normal way, on the “straight.” The only reason I turned the bodice on the “bias” grain is to play with the stripe placement, but it’s pretty pleasing aside from that, too.

      My tiras are unhemmed right now, I wanted to see how much they’d grow. :)

  6. Very interesting post. I never really thought that much about it, but now, yes, it does have a bias. I am remembering a shirt I made a few years ago and I was running short on the fabric and cut a piece on the bias. It was a yoke piece and even though it was stabilized it always rippled a bit. It was never quite right. It ended up being a top for a pair of PJ’s since it was not public worthy. Thanks for the info, I will pay more attention now. Your Chevrons are lovely.

  7. I love knit fabrics – they are so fascinating to me, and I never get to play with them enough. I did notice the slight ripple in my first Renfrew I sewed up (the one with the bias stripes that chevron at the center). Anyway, this post was extremely interesting, so thanks for giving me something to dwell on today :)

    Also, it just makes me want that Tiramisu pattern even more – I was thinking about it this morning (does that make me a weirdo? lol) and how I want to make it in a deep jewel-toned emerald green wool jersey. I may try to source fabric while I’m in Chicago next month – do you have a ballpark yardage I should try to buy? I wear a 0-2 in Colette & Sewaholic patterns.

    • Well, since you’re so teeny, I’d say 2 yards, 2 and a quarter if you want to be careful. That’s of a 55″-60″ wide fabric. :) (and not weird, if I could I’d speed up production and have the patterns out tomorrow!)

      Oh yes! Renfrew has the chevroning, too. How does it wear for you?

  8. Coolio—really intereting! And probably the best way to figure something out. The Tiramisus look smashing (especially love the red, gee, what a surprise! :)

    • Heheheh. I like wearing red… I always feel sharper… This red is just a little bit warm, I was worried I might not be able to carry off so much of a slightly off shade of red but I think it works ok. :) Stephen likes it, too.

  9. This post is genius – and I really do love that dress. I think it will suit my shape well as I have a large bust, short waist and a narrow frame. It’s almost impossible to tell how something will fit from a photo of another person wearing the garment. However, you appear to have a “deep bust”, much as mine is. I usually find that (unaltered) empire lines do not work because there isn’t adequate depth in the draft of the bodice. I am very intrigued to read about the bias cut of the bodice leading towards length in light of the grain and gravity. I don’t have enough experience of sewing a bodice on the bias but I’ve very interested to explore that. I wonder if your pattern might fit me without adjustment in light of that.

    Can you tell us a bit more about the kind of bust fit you’re leaning towards for your slopers?

    • Yeah, short waist, deep bust, narrow frame sounds familiar to me!! The deep bust is such a dignified way to describe the issue, I have been known to go for other terms, myself… ;) So yeah, I’ve always found that unaltered empire lines end up along my mid-boob region, and I hate that… Empire (especially when teamed with a midriff section) can be quite flattering on a larger bust when done well…

      I think it’s likely you’d fit without an alteration. I’ll write a full post on the sizing and what I think about it soon… But basically, there’s 5 “high bust” sizes between 30″ and 50″. Each of those has 4 “cup” sizes, though they may not correspond to someone’s exact cup size… It’s more a way to say “30D has more room in front than 30A.” This means Tiramisu basically has 20 different options for the front bodice piece. I have a chart I’ll share soon, the math is cool. :)

      On top of that, I sketched the alteration lines on the pattern pieces and the simple bust alteration is one of the support tutorials I’ve been working on for Tiramisu in the Cake Shop. (Shhh! New website I’m building, should be great fun! Lots of top content..) I want to make patterns that feel friendly and accessible to a variety of body shapes, so the patterns themselves are created in order to be easily customizable. I’ll write a proper post about it soon, I love the way the pattern work came out on this project.

      I’ve struggled since I was 13 to dress my deep bust, so undoubtedly I’m bringing that to the table when I make my patterns. But I hesitate to say I draft for busty ladies only because that’s not the case…. But being busty definitely informs my process, there’s all kinds of boxes I tick (like- am I going to tumble out of this? Does this design sufficiently divide my bulk? etc)

      Other patterns I’m working on aren’t so “fitted”… They’re separates combinations, and the tops are modeled on the Blank Canvas Tee, which seems to work well on a variety of body shapes. But I do want to use specialized fitting (like cup sizes, and I’m working out a pants system…) where it’s appropriate. And I’ll always explain what’s going on… Does that make sense?

      • Oh, this is terrific! Deep bust is not just a term :-) As a bra aficionado, I’ve learned how 2 women with the same bra size can have radically differently shaped breasts. A woman with wider set, proportionately flatter breasts will fit that bodice totally differently than I will. The deep breast is an interesting challenge – but it means (as I’m narrow) that I’m not totally screwed when it comes to wearing RTW. I make up for the length required in the bust because I don’t require the width.

        I have to say that I haven’t been so excited to make a garment in a long time. I think the dress is fantastic – so elegant, but simple. And I think it’s going to work incredibly well on women with my frame.

        • You’re right, a deep bust is more S-shaped… That’s definitely what I’m dealing with myself… Though like you said, it works with some RTW and etc…

          I’m pleased you’re so excited! She’ll be ready soon, I just want everything to be “just so” with the instructions etc… :) It’s a really interesting process, and I’m glad I started with a nice simple dress like Tira.

    • Thanks! I just get curious, then experiment… Sometimes the experiments don’t work out, and sometimes I figure out something interesting… :) I like my Bow Tie Tees a lot…

  10. Funny, but I’ve always assumed that bias would behave like bias, regardless of jersey/knit/woven properties. That said, each fabric seems to have it’s own bias properties, but I always like to play it safe and treat a knit bias carefully, as it already has stretchability, and I really don’t want things to grow exponentially. I love your Tiramisu – what a perfect name for a dress that works! Pick-me-up, indeed! Your red version is wonderful. Funny, I’ve found myself gravitating to a similar silhouette recently for a couple of dresses.

    • I like this silhouette, too..! It’s flattering and feminine and easy to wear. So easy to wear. hehehe, yes, I like the Pick-Me-Up meaning, too. Mmm, reminds me I want to make a Tiramisu to eat soon…

      Some knits are a little more prone to growing, like bamboo… But I agree, discretion is always the better part of valor. ;)

  11. I have DEFINITELY noticed a bias behavior from my knits! I’m glad to see someone acknowledge it, since as you noticed, there doesn’t seem to be much discussion about it.

    BTW, I just bought the perfect fabric for my future Tiramisu! I hope three yards is enough, because by the time November rolls around I doubt the discount store will still carry it!

    • I would think 2- 2 1/4 yards of a 55″-60″ wide fabric would suit you, Cindy. 3 is being very careful! I’m so excited to get this pattern out and see what happens, I can’t wait to see yours. :)

      Definitely a bias, but it seems more pronounced… I’m sure there’s more to learn about knit bias.. Very interesting.

  12. Oh my goodness, I really love the red version.

    I was thinking of doing something like the bow tie tee (with a less open neckline!) because the jersey I have has a noticeable slub. I’ll have to keep your observations in mind. :)

    (PS. I’ve been making pants and shorts galore, and have some across some… problems. I’m still sewing, though!)

    • Let me know how the tee goes, I really like the way your mind works. :) You can drop me a line about the problems, I’d be interested to problem solve a bit… :)

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