Today I had my custom liners made. We refer to the practice as "foaming" because the liners are made from an expanding chemical reaction that forms a dense foam once inside the liner. Previously I had performed this peculiar and somewhat esoteric practice on unsuspecting customers in spite of never having had it done to me.
The principle is as follows. Ski boots need to be made of a stiff material in order to drive the ski with sufficient force. Due to it's weight, relative flexibility, price, etc, plastic has been chosen for the manufacture of ski boots (polyether to be precise). Plastic, it turns out, is not the most comfortable footwear in the best of conditions. Now take this vise-like, generic plastic hull, shove your foot into it and subject yourself to subzero temperatures, water in all forms, and high-force impacts. No small wonder skiers' feet aren't happy at the end of the day. Traditional liners are basically layered foam that breaks down quickly (pack-out) and do little except keep the foot warm and protect it from the nefarious plastic. The foam liner is custom-made to the user's foot, allowing the material to be more dense, last longer, and actually improve the performance of the boot. Because the liner contours to the foot and holds it snugly, energy is transmitted rapidly to the ski. OK, now for the fun part.
The un-injected custom liner looks like a mutant octopus--no fewer than 6 plastic tubes protrude from it's surface (see photo below). Two tubes run into the liner just above the ankle near the achilles, one runs into the tongue, and three exit tubes run from the top of the foot where the tongue of the liner meets the foot. Foam runs into the top tubes, fills all the empty space in the boot and exits through the tubes at the bottom.
Succinctly, the process of foaming is medieval. It's painful, involves brute strength, severely decreased circulation, pliers, hair-pulling, sweat, physical exertion, and a highly exothermic chemical reaction (explosions are highly exothermic, fyi.) People pay lots of money to have this done.
Step 1) The bootfitter places very sticky pads over the ankle bones (if they're hairy prior, they won't be afterwards). The pads are followed by a sock, then a toe cap, then a plastic bag. The toe cap keeps the heel pushed back in the boot (ie crunches your toes) and the plastic bag protects the foot from the foam if something goes wrong. The pain begins here.
Step 2) The bootfitter yanks on the liner with pliers to remove wrinkles, then buckles the boot to obscene tightness. On top of this, a strong velcro strap is wrapped around the tongue of the boot as tight as it can be pulled. This keeps the tongue from getting too fat with foam and doubles as a tournakit.
Step 3) The game of seconds begins. The bootfitter mixes the chemicals and shakes for 15 seconds. Too long and the bottle will explode--make no doubt about it. After 15 seconds the lid is removed and QUICKLY screwed into the injection tubes on the tongue. At this point the customer feels as if all the blood is being pushed from his/her lower leg (it squeezes like a blood pressure test on 'roids).
Step 4) Buckles are tightened even further, more chemicals are mixed and the heel section of the liner is foamed. For two minutes the customer is asked to pull downwards against two steel bars positioned on either side of the foaming stand. This is crucial to keep the heel set firmly in the boot. The foam pushes with enough force to move the foot if the person does not pull hard enough.
Step 5) The process is repeated for the other foot.
Step 6) The customer stands in the boots for five minutes before the buckles are loosened and circulation can return to the feet.
Bottom line? I will be much more sympathetic when customers complain that the process is uncomfortable. It is.
The principle is as follows. Ski boots need to be made of a stiff material in order to drive the ski with sufficient force. Due to it's weight, relative flexibility, price, etc, plastic has been chosen for the manufacture of ski boots (polyether to be precise). Plastic, it turns out, is not the most comfortable footwear in the best of conditions. Now take this vise-like, generic plastic hull, shove your foot into it and subject yourself to subzero temperatures, water in all forms, and high-force impacts. No small wonder skiers' feet aren't happy at the end of the day. Traditional liners are basically layered foam that breaks down quickly (pack-out) and do little except keep the foot warm and protect it from the nefarious plastic. The foam liner is custom-made to the user's foot, allowing the material to be more dense, last longer, and actually improve the performance of the boot. Because the liner contours to the foot and holds it snugly, energy is transmitted rapidly to the ski. OK, now for the fun part.
The un-injected custom liner looks like a mutant octopus--no fewer than 6 plastic tubes protrude from it's surface (see photo below). Two tubes run into the liner just above the ankle near the achilles, one runs into the tongue, and three exit tubes run from the top of the foot where the tongue of the liner meets the foot. Foam runs into the top tubes, fills all the empty space in the boot and exits through the tubes at the bottom.
Succinctly, the process of foaming is medieval. It's painful, involves brute strength, severely decreased circulation, pliers, hair-pulling, sweat, physical exertion, and a highly exothermic chemical reaction (explosions are highly exothermic, fyi.) People pay lots of money to have this done.
Step 1) The bootfitter places very sticky pads over the ankle bones (if they're hairy prior, they won't be afterwards). The pads are followed by a sock, then a toe cap, then a plastic bag. The toe cap keeps the heel pushed back in the boot (ie crunches your toes) and the plastic bag protects the foot from the foam if something goes wrong. The pain begins here.
Step 2) The bootfitter yanks on the liner with pliers to remove wrinkles, then buckles the boot to obscene tightness. On top of this, a strong velcro strap is wrapped around the tongue of the boot as tight as it can be pulled. This keeps the tongue from getting too fat with foam and doubles as a tournakit.
Step 3) The game of seconds begins. The bootfitter mixes the chemicals and shakes for 15 seconds. Too long and the bottle will explode--make no doubt about it. After 15 seconds the lid is removed and QUICKLY screwed into the injection tubes on the tongue. At this point the customer feels as if all the blood is being pushed from his/her lower leg (it squeezes like a blood pressure test on 'roids).
Step 4) Buckles are tightened even further, more chemicals are mixed and the heel section of the liner is foamed. For two minutes the customer is asked to pull downwards against two steel bars positioned on either side of the foaming stand. This is crucial to keep the heel set firmly in the boot. The foam pushes with enough force to move the foot if the person does not pull hard enough.
Step 5) The process is repeated for the other foot.
Step 6) The customer stands in the boots for five minutes before the buckles are loosened and circulation can return to the feet.
Bottom line? I will be much more sympathetic when customers complain that the process is uncomfortable. It is.
The sock, the pads, the toe cap, and the plastic bag. Have fun!
This shot is taken by a customer of someone using pliers to remove wrinkles from the liner.
Here is a boot with the custom liner in it. The foam is visible flowing into the tongues of both boots. Notice the exit tubes coming from the toes and the tubes at the rear of the boot. The chemicals can be seen in the background. The small dark bottle is poured into the large pink one before shaking.
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