To a great extent, our ultra heavy flannel (UHF) shirts define Iron Heart: heavy, rugged, but amazingly wearable. The 12oz fabric is woven with Aspero cotton from the foothills of the Andes mountains. We double brush it on the inside and single brush it on the outside, resulting in a very soft yet substantial, thick, warm and windproof flannel. 

New for FW26, this over shirt represents a first for Iron Heart: an over dyed UHF in a solid colour way. To achieve this rich camel-brown shade, the shirt is first made using a regular yarn-dyed UHF fabric before being over dyed in the same colour after construction. This process deepens and intensifies the hue, softening the fabric further while retaining the signature UHF heft.

Designed as an over shirt, this cut is an ideal winter layering piece, worn either as an outer or mid layer. Like our traditional work shirt, the cut includes classic patch chest pockets (complete with a pen holder) and button fastenings throughout. Where it differs is in its looser fit, straight hem, and split side-seam gussets, which are more characteristic of our mechanic shirt cut. Wear true to size for layering or a casual, relaxed fit, or size down for a more fitted silhouette.

 Made In Japan

12oz Japanese Ultra Heavy Flannel (Overdyed)

- 100% aspero

Aspero is a naturally occurring wild cotton that is found in the foothills of North East Peru, and being a tree, is not farmed, and so is one of the purest most organic cotton available. As it cannot be mass-produced, it has been highly prized for generations by the indigenous Peruvian population for its qualities of fineness, softness, volume, and also strength. Iron Heart use Aspero cotton in their famous Ultra Heavy Flannel (UHF) shirts (eg. IHSH-232).

cotton

- Single brushed face / double brushed reverse

- Twill weave
- Reactive-dyed warp

In weaving, the weft is the term for the thread or yarn which is drawn through the warp yarns to create cloth. Warp is the lengthwise or longitudinal thread in a roll, while the weft is the transverse thread. A single thread of the weft, crossing the warp, is called a pick. Terms do vary (for instance, in North America, the weft is sometimes referred to as the fill or the filling yarn).

and weft

In weaving, the weft is the term for the thread or yarn which is drawn through the warp yarns to create cloth. Warp is the lengthwise or longitudinal thread in a roll, while the weft is the transverse thread. A single thread of the weft, crossing the warp, is called a pick. Terms do vary (for instance, in North America, the weft is sometimes referred to as the fill or the filling yarn).

- Fade-resistant finish to ensure a steadfast colour

- Post-construction, this shirt is over dyed using the same colour as the original yarns to deepen and intensify the hue

Cut & Features

- Work shirt
- Oversized fit
- Button fastenings
- Chest pockets with pen holder
- Straight back yoke
- Straight hem with split-seam gussets

Optional Upgrades

This shirt is fitted as standard with four-hole buttons.

Constructional Stitching

- Single and double needle stitching
- Poly/cotton thread for enhanced strength
- Bar tack pocket reinforcements
- Chain stitched side seams
- Felled internal seams

One-Washed & Over dyed

- Post construction, we wash the completed garment in an aggressive industrial washing machine. This process removes most of the potential shrinkage

- Following this, a high-temperature over dyeing process removes any remaining potential shrinkage
- No further shrinkage is expected if washed in accordance with our guidelines

Care Guidelines

• We recommend washing this garment at 30°C with a low (or no) spin cycle. Hang dry, do not tumble dry