Denim is divided into two groups, selvedge and non-selvedge.
The only different between these two are the cotton is loomed with a different process. This gives them a different seam and arguably a different level of durability.
So what's the difference between a shuttle loom and projective loom?
A shuttle loom is the same loom that you see in movies with tons of strings looking all crazy.
(Cool Irish lady explaining a old school shuttle loom, 2:45)
New shuttle looms operate in the exact same way.
They've been modernized and automated. Making them look different but the concept is the same.
The weaving motion for any loom is pretty similar. Yarn goes up and down and locks down yarn that is been shot across perpendicular to it.
(video describing the general way every loom works)
A shuttle loom is different from that video in that the shuttle carries the yarn across then is turned around and shot back.
To do my best to describe how it works.
- Many threads of yarn are run parallel with each other.
- These threads are alternated up and down.
- This alternating creates a gap.
- A boat shuttle, with yarn inside of it, is ran through that gap.
- After the boat shuttle goes through the yarn alternates from up to down
- This creates a weave.
- Then the shuttle turned around and shot back across repeating the process.
(It creates this weave pattern)
In the denim world this process creates a very clean edge to the denim. This the selvedge.
It is created because of the "weft' turn in the yarn.
(Denim selvedge inseam create by the weft)
The problem with shuttle looms, even the industrial ones, is that they are slow.
A 'pick' is one time across the loom. In a shuttle loom the boat goes across the shuttle making one weave 150-200 times per minute.
Some of the more modern looms can great 5 times that amount. They just won't have the same sharp looking selvedge.
A shuttle loom uses a boat to shuttle yarn back and forth as it is weaved down by yarn running perpendicular to it.
It creates a very clean selvedge seam in denim. This is considered to be more durable then a non-selvedge edge.
These looms are much slower making it hard to meet the demand of denim or other cotton products.
I'm going to use the term 'projective loom' as a general term for all other types of looms.
This will include:
- Air jet
- Water jet
I'm doing this because in the denim world all of these create the same outcome. An inseam without a selvedge.
(Not a great video but it has some side by sides of selvedge and non-selvedge)
All these main difference to the shuttle loom is that they shoot a single piece of yarn across. They don't weave a long piece of yarn back and forth like a shuttle loom.
Cutting the yarn every time create a more rough edge which is seen in the inseam of a pair of jeans.
This rough edge is sewn to reinforce.
(Great video explaining all the looms, a little boring though, 5:57)
These looms can create over 1000 picks a minute. Meaning they create 1000 weaves per minute. A shuttle loom can only get to about 200.
This makes them much more cost effective.
The bottom line:
More modern looms, such as the projectile, create fabric faster and cheaper. It's arguable if the edge they create is more durable or not.
It definitely isn't as clean looking.
In the denim world selvedge denim is selvedge denim is preferred. This is because the shuttle loom create a very nice inseam and a very durable denim.
The projectile loom still creates a great denim. It's inseam is going to be rougher but in theory it should be just as durable.
Here at Washington Alley we create a raw selvedge denim created completely in the U.S. including the shuttle loom
You can shop for those, here
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