Spiral Trousers: The Holy Grail of Pants

Funky pants, the result of much trial and error

These trousers are based on the work of New Zealand Fashion Designer Holly McQuillan’s zero waste pattern cutting method. I was inspired to try them out after watching her give a really great lecture on youtube. As part of her higher education at Massey University NZ McQuillan created an open access  modular zero waste fashion system called make/use.

The crux of zero waste fashion design is that all the pattern pieces of a garment are nestled creatively within a larger rectangle which fits standard fabric roll lengths. To put it into perspective here is a comparison between a standard pants pattern layout and McQuillan’s zero waste pants layout.

Traditional vs zero waste pattern pieces. Zero waste image sourced at: https://fashion-incubator.com/zero-waste-fashion-design-an-interim-report/

You can see that the standard pattern layout generates lots of negative space no matter how well you try to butt the pieces up together – an average pants layout could require from 1.5 to 2.5m fabric with a significant portion of that left over as odd shaped strips, points and other annoying shapes which are hard to re-purpose. The zero waste pattern is just a rectangle cut in half diagonally, and its under 1m wide!

Economy and waste aside it is the unique forms that evolve from zero waste pattern cutting that appeal to the artist in me.

Unfortunately while most projects on make/use are well supported with diagrams, downloadable patterns and written advice the spiral trousers project are not. There is no construction information for some reason. This led me to try and backwards engineer a pair based on what I could observe in photos and a technical drawing I saw in the aforementioned lecture on youtube.

I am really grateful for the generosity of young designers like McQuillan and Julian Roberts mentioned in my last post on subtraction cutting who break the mold be sharing rather than shielding their discoveries and techniques.

In the spirit of sharing creativity here is what I learned about constructing spiral trousers:

1) You can make them from just one rectangle bisected with a diagonal through
the middle but it only works if your fabric has no right side – meaning  it is exactly
the same on both sides.

2) If your fabric has a pattern or noticeable colour shift between right and wrong sides
you will have to make a bigger rectangle yielding two pairs of pants. This is
required in order to get a left and right leg in matching fabric.

3) Paper models are really helpful as McQuillan suggests in her lecture. Especially in the beginning when I was struggling to compute how a triangle can become a trouser leg, it was breaking my brain!

A model helped me wrap my head around how the diagonal seam connects to make a trouser tube

A further note on paper models: After stuffing up…ironically quite wastefully…on full size fabric versions a few times I finally started making scale models in paper so I could
double check the measurements at key areas like hip, thigh, knee, calf, ankle. I measured these on myself then made sure that the model reflected the dimensions in miniature form – for example 60cm width needed for thigh circumference was reflected in a 6cm measurement just below the crotch on the model pant leg. Also making a model allows you to check the overall length so you don’t get unexpected results like I did as you will see.

4) The fit is modified by darts at the waist which are standard but also at the back of the leg which is an uncommon construction method but it works surprisingly well.

5) The crotch curve can be achieved by tracing off the front and back curves of a pants pattern you like – or copy it from a pair of commercially bought pants you own. This piece becomes a patch pocket later in the process.

Crotch curve template – a template like this gives very high waisted pants.

On to the prototypes.

I started by following McQuillan’s recipe of 75cm wide x 150cm long for a size 10 pair of pants but I must have more junk in the trunk than I thought because I could not get them fastened over my thighs and hips nor could I get my feet through the lower legs. I had to cut slits at the cuff to get them on.

First attempt – way too tight!

I made the waist wider the next time 79cm and cut the rectangle to 116cm thinking that would give me pants 116cm long.  It was a revelation to me that I lost length when sewing up the seam – the finished length was 32cm shorter than planned. I think this happens because the seams travel somewhat horizontally around the leg. Moral of the story is make the pants longer than the finished size you desire. The hips area was looking promising here despite the shock of making unexpected knickerbockers.

Second attempt. They’ve got a bit of a Louis XIV thing going on.

Because I got sick of making pants that I couldn’t get my foot through I made sure that my next attempt factored in 5cm extra width at the cuff end of the triangle. These ones were made from a rectangle which was 84cm wide tapering down to 5cm wide, the length of the rectangle was 148cm which ended up as roughly 120cm long finished pants.

Last attempt

I had a length discrepancy of about 5cm in one of the pant legs – one was shorter than the other – and I put it down to uneven drawing and or cutting of the fabric. I think one triangle had a bit more girth possibly stemming from my method of finding the diagonal through the rectangle which involved folding the fabric over on itself and eyeballing it..I’m sure there is a better mathematical way to do it. I evened the leg length out when I hemmed the pants making them more of an unusual  cropped bootleg shape.

As you can see in the photo above left – I chose to thread trace the darts at the waist because as mentioned earlier one side is “right side up” and the other is “wrong side up” if you thread trace you can see your markings on either side. The guidelines down the back are thread traced too, I used these as the basis for stitching up the long darts at the back of the leg. I waited till the fitting stage to pinch out the dart in the back of the legs. I used an elongated diamond shaped dart which was 67cm long tapering from 0 to a width of 8cm at knee height then down to 0 again.

Zipper, pockets and seam details

With this method the seam lines become a design feature. I retro-fitted a punky exposed metal zip at centre front. The waist band did involve some wastage in order to get the cute curves that the zipper ends follow but I thought I was allowed a little splurge after being so otherwise mindful.

The crotch pieces get sewn on as patch pockets, you could do some decorative folds to decrease their length for a more conventional look but I left them as is in a truth-to-materials gesture.


I’ve been watching Spaghetti Western’s lately…can you tell?

Final thoughts:

They look good but to be truly comfortable I need to factor in a bit more
ease next time. Using a very narrow 0.5cm seam allowance grants more
ease compared to the 1.5cm seam allowances I used in this example. I
think 0.75cm seam allowance might strike a better balance between
contoured shape and ease.

**18/06/2020 Update**

I’ve been developing the idea of spiral trousers further by incorporating a sporty stretch panel into the spiral seams. See my full process and modeled outcome here.


3 thoughts on “Spiral Trousers: The Holy Grail of Pants

    1. Thank you Liz, yes I’m with you, breaking up the triangle panel with further seams does allow you to use the same side, I tried it on my “tracksuit overhaul” project. I’m interested in using amalgamated triangle panels too, ie. a bit of stretch fabric thrown in the mix.

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