UHR and how it came about.

Iron Heart’s UHR (an acronym for “Ultra Heavy Raw”) denim enjoys virtually legendary status amongst aficionados and fans of the brand, due to its fading potential, and the density of the weave.

Haraki san’s original 21oz double yarn weft denim, quickly became (and remains) extremely well loved, but the purists were looking for something more intense!  Haraki rose to the challenge and created a single weft, single warp unsanforised, “loomstate” (raw) 21oz denim, which becomes (approximately) 23oz after shrinkage.

Iron Heart’s UHR denim is actually produced in only one mill in Japan - a husband and wife team with a ‘house’ factory with just four looms, only two of which can weave UHR denim. On top of that, as it is in a residential area, they can only run 8 hours a day, producing 0.8 rolls a day (50m). When you consider it takes 2.8 metres of denim to make a single pair of jeans, you begin to understand how our UHR denim has become super limited and sought after!

UHR denim is not for the faint-hearted, the jeans are shrink to fit, sizing is a little trickier compared to sanforised denim, but the end result is definitely worth the effort.  We now produce all our core Iron Heart cuts - super slim, slim, straight and tapered - in UHR denim.


UHR being woven - sacrificial lengths of warp are used to start the process, each of these is hand knotted to the real warp and then teased through the loom before the weaving actually starts... (notice the indigo dust everywhere!)


To view our range of UHR denim, click below.

Shop All UHR

To learn more about other aspects of denim and Iron Heart products

WHAT IS SELVEDGE? WHAT IS THE M65? WHAT IS LHT? WHAT IS A DRIZZLER? WHAT IS A TYPE 3? WHAT IS XHS?

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