The Twisted Truth: Leg Twist

Superfuture reader maxbit posted the following question: I just bought my first pair of vintage Levi's 501 jeans. They fit perfectly, with one caveat: The jeans seam twists on one side. So much so that the side sam is in the front at the bottom of the right side. I'm just curious what causes this and more importantly, are there any fixes?

Although maxit doesn't like the look, many do. 
AS the look of vintage jeans has become more prized, so has the phenomenon of leg twist - a property of older twill fabrics that was originally seen as a drawback or irritation. 

Pre -70s jeans suffer from Leg Twist, to differing degrees. Leg Twist is simply a natural adjustment of the fabric, which tends to follow the direction of the weave as the fabric moves or shrinks after washing. Stefano Aldighieri, who was Director of Fabric & Finishing at LS&Co. explains it thus: “Levi’s denim were mostly right hand twills; the twill line rises to the right. During the weaving process you basically ‘force’ the fabric to be straight, perpendicular to the selvage, but at the same time you give it this direction in the construction. You lay and cut the fabric; in the early days LS&Co. patterns were cut straight along the selvage. When you wash the garments, the fabric will try to follow the direction of the weave and will pull in that direction.... hence the twisted legs, the result of the movement of the fabric. Because Lee started to use left hand weave denims, their legs would twist the other way.” 

As Stefano points out, Leg Twist is much more noticeable on jeans than on other fabrics because of the construction, with the selvage edge used on the outseam. 

Leg Twist was eliminated in the 1970s by skewing (which contorts denim to its after-wash shape) - and later revived with Levi’s Red and Engineered twisted seams jeans!

What's intriguing abut Leg Twist is that is seems to vary so much between different examples of vintage jeans. I've seen it more often on early 1970s Levi's - although, of course, I've worn more original '70s Levi's and, sadly, only one original pair of '50s. Some vintage jeans have marginal leg twist, but on the odd example, you can have the seam on the left leg rotate so it's almost on the front of the jean. So what are the variables that would cause leg twist, some but not all of the time? I asked Ralph Tharpe, who oversaw the development of many of Cone's finest fabrics and now oversees the Artistic Fabric Mills in the US, what causes so much variation in leg twist. 

"That's a good question. I think partly it has to do with the type of seam that's sewn on the inside. I think the way the jean is sewn when the operator is sewing the jean, when she sews up the right leg and down the left, if she's pulling too hard coming down the left, then she's accentuating what the fabric want to do and making the skew worse. It can be really, really bad. 

"I also have another theory, which I've never been able to prove. When I started working at White Oak I was in the quality area, and we were grading loomstate denm. They had a defect they call long sides. Long sided means one side of the denim was stretching out or was longer than the other. Maybe this was something wrong with the loom, maybe the crank arms weren't adjusted exactly the same on both sides, so the pick is going in slightly at an angle. If that were the case, and again this is totally theory, than if that were the case the skew the fabric wants to move to would be really accentuated. On the other hand, if the pick is in the opposite direction it would be reducing the skew. Anyway - it's just a theory."

So, leg twist is a product both of fabric movement, and the garment construction. 

I didn't ask Ralph whether it's possible to alter jeans after they're sewn to eliminate the leg twist as, in practical terms, it's impossible. You just have to live with it, taking comfort from the fact it's a mark of cool, old jeans. 

When my LVC '47, both pairs, started showing heavy leg twist  after their first wash, I was pleased. But plenty of people will comment that I'm twisted already.