carved shape of the insole in handwelt construction through which the upper is inseamed
Holdfasts are made by carving out grooves or trenches on the undersides of insoles, leaving a rib of leather standing proud through which to sew. The edge of the insole between the holdfast and featherline may or may not also be carved out to form a feather.
Width
Holdfasts are usually 5 to 10 millimeters wide.
Holdfasts must be thick enough to hold stitches without tearing out during inseaming or wear. On the other hand, they must be narrow enough to pass an awl through holdfast, upper, and any welt all at once, so the maker can pierce all the needed holes at one go.
Height
The grooves or channels on the insides of holdfasts are usually one third to one half the thickness of the insole.
The carving must make a holdfast high enough to pierce, sew, and hold without tearing out. On the other hand, the carving should not undermine the strength of the insole or create ridges felt by the feet during wear.
Shape
The shape of the outside of a holdfast is determined by any feather or edge beveling of the insole. Makers differ in how they carve the insides of holdfasts.
Some cut simple grooves using a groover or gum tool.
For example:
There are also handcrank machines for gouging out grooves:
- White’s Boots Drifter using a handcrank machine
- Viberg blog post on “Channeled Insole Goodyear Welt”
Some makers cut triangular trenches, usually startinb by incising a line at the inside edge of the holdfast they intend to make. The outside incisions may be perpendicular to the face of the insole or angled either in or out. For example:
The inside incisions may be made freehand with a knife:
They may also be made with a guarded-blade tool like a feather plough, welt knife, or French edger:
- Marcell Mrsan’s “How to Make a Shoe”, using a feather plough
- Siroeno Yosui Embossed Cordovan Derbies using a welt knife
The inside incisions may be steeply angled and close to the outside incisions, yielding narrow, triangular grooves that minimize leather removed, much like a round groove. They may also be shallowly angled and further from the outside incisions, yielding wider, more gently sloped trenches that require more cork or other filler, but make it easier to pass bristles or needles through during inseaming.
Some makes don’t carve out leather at all, but only make one incision and spread it away from the surface of the insole, creating a flap to sew under. For example:
Examples
- Carreducker “Learn Handsewn Shoe Making”
- Kustom Kraft (Dennis Kieback) Red Ankle Boots
- Kustom Kraft (Dennis Kieback) Tall Brown Boots