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Leather Ski Boots Construction (Part I)

Posted: Fri Dec 15, 2017 4:06 pm
by Johnny
Ski Boot Construction.jpg
How a ski boot is made at Andrew's
Leather Boots Construction
Source: David Mann / Andrew Footwear
There are 3 basic construction types used today for backcountry touring boots. Understanding them is key to choosing the right type of boot for your uses. Here they are from lightest to heaviest.

Injection Welted
These boots have leather and fabric uppers. This means that their performance primarily comes from the construction of the sole and welt, which is the manner in which the sole is attached to the uppers. Injection welted boots have rubber soles that are typically stiffened with a nylon or plastic shank. They are joined to the leather uppers by way of a gluing or injection type of process, hence the name. Most lightweight hiking boots seen these days also use an injected welt construction. So, one way to identify an injected welt is that they look something like modern hiking boots. Injection welted boots do not have visible stitches along the welt.

Some have questioned the durability of this type of boot type and it is unclear if they can be resoled in a cost effective manner. Still, the injection welt and modern nylon reinforced shank make these boots lighter, more watertight and better turning boots than their Norwegian welt counterparts. In general, I would recommend a injection welted boot over a comparable Norwegian welted boot for these reasons.

Norwegian Welted
These leather boots look like old fashion hiking boots with big stitches around the welt. This used to be the primary construction type and today this type of boot is still being produced by Garmont and Alico. Typically, the boot derives its torsional strength from its midsole. While these boots can be resoled in a cost effective manner, they have a well earned reputation of being torsionally soft. An old timer once advised to not use leather boots to ski hard pack with skis any wider than 65mm at the waist for just this reason.

Norwegian welted boots are also prone to getting wet, even when used with glued on rubber-randed super-gaiters. The reason for this is that it is practically impossible to entirely waterproof the welt and mid-sole (between the outer sole and the stitches). If you do decide to use a Norwegian welted boot and keeping your boots dry is important, there are some things you can do to minimize (but not eliminate) water intrusion. First, seal the stitches with good sealant. My favorite goop for boots is Seam Grip. It stays flexible for years and resists being pulled away from the boot. Before you apply the seam grip, clean the stitches and leather thoroughly with a solvent like acetone to remove any grease or wax from the leather, which prevent the Seam Grip from bonding with the leather. Note, the heavy solvent may permanently strip or change the color of your boots. Pour the Seam Grip into a syringe style infant medicine dispenser which are available and most pharmacies. This will allow you to lay the seam grip into the seams accurately with a minimum of mess.

The second thing you can do is to use rubber-randed super gaiters, which are available in both insulated and non-insulated versions. I glue mine on at the beginning of every season with Shoe-Goo to prevent them from pulling off of the toes of the boot and to create a more water-tight seal. The gaiters are tight, they may curl the boot toes upward toward the sky. Some folks don't glue their gaiters on for this reason. Personally, I get so annoyed by gaiters popping off in the field, that the risk of curling my boot is worth it. I glue my gaiters on at the beginning of the season and leave them on till the last of the spring skiing. Note, removing glued on gaiters will almost certainly mar the finish of your leather boots.

A good Norwegian welted boot will last for many, many, many years, especially if they are repaired and resoled by a good cobbler. But, their weight, the general lack of torsional stiffness and lack of waterproofness compared to injected welted boots makes it hard for me to recommend them.

Norwegian Welt Boots.jpg
This prestigious handicraft technique is characterised by an exposed double seam that binds together the upper, lining and insole. The first seam connects the upper to the insole and the second one anchors the upper to the midsole that shall subsequently glued to the sole. This is an especially difficult process, that requires a lot of time and a lot of precision, and is therefore characteristic of only a few companies who still have very skilled master shoemakers in their staff. The final result is a vintage-looking shoe, exceptionally long lasting and completely reliable.
Norwegian Welt Telemark Boots.jpg
A closer look at how the Norwegian Welt is made
Plastic Double Boots
Back in the day, the ultimate in warmth was provided by double leather boots. These had a inner bootie that was placed inside of a outer leather shell. While heavy, these boots had good reputation for being warm. Today, these boots have practicly disappeared and have been replaced by plastic double boots. The plastic shells of these boots are generally lighter and more durable than their older leather counterparts. They are also waterproof.
Alico Double Telemark Boot.jpg
The Alico Double boot
In recent years, thermo-modable liners have become more widely available. These liners are heated up so they will mold to your foot and give you a custom fit. They also have the reputation of being even warmer and, get this, lighter too. In fact, the lightest plastic double boots now rival some single leather boots in weight.
Scarpa T4 boot and liner.jpg
The Scarpa T4 Double Boot
These boots derive their torsional stiffness and power from their plastic shells. Of all of the boot constructions available, they provide the most turning power due to this. However, the 75mm duckbill on plastic boots is stiffer. While this helps provide more turning power, this can also impede striding efficiency.

For more detailed information about boot construction, check out Part II of this article right here.

Re: Leather Ski Boots Construction (Part I)

Posted: Fri Dec 29, 2023 2:00 am
by JB TELE
If you seam grip the stiching on a norwiegan welt will that cause any issues with resoling them in the future?

Re: Leather Ski Boots Construction (Part I)

Posted: Sat Dec 30, 2023 5:09 pm
by lilcliffy
My very limited understanding is that wax-based waterproofing products (eg snowseal) can interact with certain adhesives- making resoling (etc) challenging.

What are you going to seal the welt with?

Re: Leather Ski Boots Construction (Part I)

Posted: Mon Feb 05, 2024 4:50 am
by randoskier
lilcliffy wrote:
Sat Dec 30, 2023 5:09 pm
My very limited understanding is that wax-based waterproofing products (eg snowseal) can interact with certain adhesives- making resoling (etc) challenging.

What are you going to seal the welt with?
Berghaus Yeti Gaiters- end of problem!

Re: Leather Ski Boots Construction (Part I)

Posted: Wed Feb 07, 2024 11:24 pm
by phoenix
I came across a recommendation for Seam Grip to seal the stitching a few decades ago; used it on a couple or few pairs of leathers and it help up flawlessly. I had a pair of 25 year old Alicos sealed with it, and they were in excellent shape, never any hint of de-lam.

Re: Leather Ski Boots Construction (Part I)

Posted: Sun Feb 11, 2024 11:54 am
by blitzskier
excuse the slight off topic, but what do you guys do when the 3 pin holes in the boot sole get damaged?

Re: Leather Ski Boots Construction (Part I)

Posted: Mon Feb 12, 2024 1:48 pm
by phoenix
"excuse the slight off topic, but what do you guys do when the 3 pin holes in the boot sole get damaged?"

Pertinent question! Answer is: 'Smile Plates'. a pair of stamped metal plates with the standard 3 hole placement. You need to grind a slight depression in the sole so the plates are flush with the sole, then pre-drill a few holes in the sole for the plates to screw into (with some epoxy to the insatallation also - but don't clog the 3 pin holes!)
A few places have carried the Smile Plates over the years, and they're getting harder to come by. I think Telemarkdown has some, otherwise Aker's xc catalog. 'Bluebird Day', I think part of FreeHeelLife had them a couple of years ago, not sure if they still do.
Those plates have been around for decades, and they work.

Re: Leather Ski Boots Construction (Part I)

Posted: Sat Feb 17, 2024 12:24 pm
by blitzskier
why thankyou i never knew about those plate. i'll file it away in my head for future use...

also another question...

my 3 pin bale clamps seem to be getting softer , at the higherst setting on the ratchet clamp. i'm guessing its the new enviromentally-friendly recycled rubber they used on these modern 3 pin boots.. any idea how to increase bale clamp pressure ?

Re: Leather Ski Boots Construction (Part I)

Posted: Wed Feb 21, 2024 9:07 pm
by phoenix
"my 3 pin bale clamps seem to be getting softer , at the higherst setting on the ratchet clamp. i'm guessing its the new enviromentally-friendly recycled rubber they used on these modern 3 pin boots.. any idea how to increase bale clamp pressure ?"

Does it still hold firmly enough the highest setting? And by highest, do you mean just the first click on the binding... meaning not the tightest? I don't really recall my bale tension changing noticeably with any of my boots (softer leather xc boots with molded soles, medium or heavy leathers with Norwegian welted soles, or any tele boots). It wouldn't be difficult to add thickness (there was a thread about that on the main forum), but before doing that, what boot and what binding are we talking about?

Re: Leather Ski Boots Construction (Part I)

Posted: Tue Mar 12, 2024 12:39 am
by blitzskier
i concluded its the new thinner duck bill design and maybe cheaper rubber that's become a bit soft, thus why the clamp tension is not the same as when i first used the alpina montana boots, with voile 3 pins..

i'm saving up for scarpa t4 to remedy the issue