Knitwear Design 101 | Drape, Loft, and Lustre

This is really part 3 of my fabrication series-within-a-series (you can read part 1 and part 2 at the links), and it’ll also be the last Knitwear Design 101 post of the year at least.

Drape, loft and lustre are three properties of fabric and fibre that aren’t always understood or exemplified, and I wanted to share my take on them today. In short, they show the following:

  • Drape – How reactive fabric is to gravity
  • Loft – How reactive fabric is to air
  • Lustre – How reactive fabric is to light

All three properties are, in some way, a measure of how matter interacts with forces or elements; the environment.

Drape

In my mind, drape is best understood on a sliding scale because all fabrics, never mind all things on planet Earth, will react to gravity.  Using the notion of a scale – maybe even a circular model or points-based system – also allows you to take into account numerous qualities of fibre type and construction.  Heavier fibres, such as alpaca, can confer drape when worked to a looser tension or in lace; somewhat counterintuitively, lofty fibres or lightweight yarns such as pima cotton can exhibit drape because of their weightlessness. 

Assessing drape can be complex, especially if it’s crucial for your design, but I promise you don’t have to be a physicist! – you just need to be prepared to experiment.  If you’re designing patterns to sell, pass on as much information as you can to your knitters so that they understand how drape affects your design, and always leave tolerances to accommodate individual tension and yarn choice.

To assess a fabric’s drape, it’s best to work with a square shape.  Pick your fabric up by the corner and note how it behaves when held between a thumb and finger.  If you’re holding a knitted or crocheted swatch, pick any corner you like; if you’re holding a dress fabric, make sure your piece is cut on the straight grain. If it’s not, do your best to find it before you do this test. The more drape a fabric has, the more readily it will form a vertical shape when dangled by a corner.  Fabrics with very little drape – typically described as having ‘body’ – will remain hanging perfectly square; fabrics with drape will curl and form waves or folds.  The quantity of curls, waves or folds formed is proportional to the drapey-ness of the fabric.

Loft

Close up of two lofty fibres and fabrics. A mint ball of organic brushed cotton is nestled against some cerise mohair/silk knitted lace.

Mohair and other fluffy yarns have an interesting quality known as loft.  Whilst drape is a measure of how fabric reacts to gravity, loft is a measure of how fabric interacts with air; buoyancy, in some cases.  Lofty yarns are often lightweight, and this typically bestows amazing meterage.  You will get a lot of yarn per gram!

Spinning and fibre construction technology has developed enough to create lofty yarns that contain no mohair, so it is possible to find cotton, cashmere, wools, or other blends that have a lofty mohair look and feel without irritating the skin.  If mohair is used, lofty yarns are spun with a core fibre that comprises a long filament – usually silk, but synthetics are a cheaper option – and the relatively short fibres of mohair are bound to this core filament.  This contrast creates loft – and the halo that so many knitters and crocheters love!  If wool, cashmere, or cotton is spun to create a lofty yarn, the spinner can vary the techniques used and use fibres of different lengths for the core and ‘fluff’ (yes, that’s a technical term 😉).

I like exploiting loft for layered pieces, or those times when the weather is warm during the day and drops to a mild chill after sunset.  You want the benefit of warmth without the heaviness or additional bulk in your bag for several hours.  One of the best things about lofty fabrics and fibres is their capacity to trap air as they react to it, which is as close as you can get to a portable radiator.  Loft is knitting and crochet’s answer to secret pyjamas!

Lustre

On the right, a pale mint matte organic cotton; on the right, a peach wool/silk. Although this isn’t a like-for-like comparison (different textures on each swatch, not to mention different hues), the wool/silk has more lustre on account of its smoothness, sheen, and clean reflection of light. The mint swatch also reflects light, but it is more dappled due to the matte texture of the yarn, textured broken rib fabric.

Lustre is important to bear in mind if you’re planning to knit or crochet something textured because it adds another layer of complexity to the way that light hits the surface.  If you’re into photography or another visual arts discipline that involves working with and controlling light, you may appreciate this discussion!

By itself, lustre indicates a fibre’s capacity to interact with light.  All fibres will do this, of course, but a highly reactive fibre (e.g., mercerised cotton) will have more lustre – sometimes described as gloss or sheen if particularly reflective – and a lowly reactive fibre (e.g., brushed cotton) will reflect very little.  In the middle you’ll find various instances of dappled or scattered light.

This is important because adding texture – or changing the surface – creates another opportunity for light to interact.  For that reason, I always begin with a stocking stitch or stockinette swatch when knitting; if crocheting, my default stitch is a UK treble (US double), which sits nicely in the middle of the stitch height scale.  These two fabrics are as smooth as it gets for me, so if lustre is important, I start there; the yarn or fibre’s capacity to reflect light will be at its best.

If you’re assessing a yarn’s lustre, take care to work in one colour as you swatch.  Colour itself is light, and will add another dimension or possibly confusion.  Lighter or darker colours will affect how well the eye perceives texture, which is why Aran sweaters are typically photographed in a light-coloured yarn – and note that these yarns are matte, or poorly reflective.  A lustrous yarn would fight with the beautiful textures knitted into each stitch, and your photographer may have a hard job on their hands – especially if you’ve chosen a colour with a fast wavelength like red or pink!

A final word on scale

It’s easy to get lost in a world of little squares when testing out ideas, but always remember to keep a close eye on things when you’re knitting your final sample – especially if it’s a garment. Any properties of the swatch (please make sure you take finishing or laundering into account) will be magnified in the sample.

For example, some drapey fabrics hold a lot of water when being washed. If care needs to be taken when finishing or washing, or if there are signs that the garment may lose its shape, you may need to add seams for stability. This could be the difference between picking up stitches for the neckband as opposed to leaving them on hold – or it could be knitting something flat instead of in the round.

I will add more posts whenever the mood takes me, but I hope you’ve enjoyed this monthly series to date! Again, you can read part 1 and part 2 if you need to catch up – and if you’ve found my posts helpful, please feel free to buy me a Ko-Fi or share as you like. It’s much appreciated 😊

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