Originally Posted by ajv
DWFII, I am not sure to fully understand and in order to improve our deconstruction methodology I would be grateful if you could explain what the gemming exactly is and how it differs from cememting.
According to J.H Thornton there are 12 recognized methods of bottoming and attaching an outsole. Not all of them are applicable to high quality...or perhaps better to say...high priced shoes. Among the foremost is "Goodyear welted." (Parenthetically, no one, including myself, seems sure if this applies to hand inseamed as well as machine inseamed shoes). Shoemakers, trained in Traditional techniques, attach the welt directly to the insole in a process that cuts a channel into the insole and then hand stitches the welt to the leather "holdfast" that is created in the substance of the insole. Done properly this is the most secure and long lasting means of attaching welt. It will never compromise the fit and the welt can be replaced whenever wear or overzealous repair has left it too narrow to be usable. There are even machine techniques that can create the holdfast from the substance of the insole and the welt can subsequently be sewn, by machine, to it. All of this is, of course, predicated on a high quality insole with some thickness that can be incorporated into the inseam. But if done by hand, it takes time...far more time than almost any other production method...which is why it is almost never found in anything other that really high quality shoes (forget about price and the cache of brand name...I'm talking quality
not $$'s). That said, there simply is no other method that creates a better, more stable shoe. Although to be fair, Blake/rapid probably comes close provided it is done with the same high quality materials. Gemming is a process that involves laying down a canvas rib around the perimeter of the under-surface of the insole. The rib is called gemming. And its purpose is to substitute for the leather holdfast...and to do it cheaply and quickly. It can be recognized by the white strip you see in most of those photos...sometimes "pinked" sometimes not. The gemming is cemented to the insole. That is the only thing holding it (and the shape of the shoe) in place. The welt is machine stitched to the gemming and the resultant insole cavity is filled with cork. Now, it bears repeating...in almost all instances, the gemming is held in place solely by cement. And that is its first weak spot. The cement will
fail, probably even before the shoe is in need of a resole. When the cement fails the gemming slips and the shoe will walk out of shape. And anyone attempting to resole without the original last, faces the nearly impossible task of trying to re-position the gemming. Moreover, canvas is far more fragile than leather. If cotton canvas is used, it is subject to bacterial action--rot, in other words. Stitches pull through, the welt itself comes loose, and moisture and dirt enter the shoe. Gemming also frees the manufacturer to select thinner and cheaper grades of leather for the insole...or eschew leather altogether and use fiberboard insoles. Nothing visible, nothing immediately apparent will alert the customer to this further debasement of sound shoe technologies. Many manufacturers put a Poron or other cushion insole on top of the fiberboard insole and tout the whole as a "comfort" insole. If an insole is made of good leather it will last for literally decades. If the shoe is inseamed directly to the leather, the inseam...and therefore the shoe...has the potential to be worn frequently, repaired regularly and might still be passed onto the next generation. What is more, a leather insole will form a "footbed" under the foot that will ensure comfort for the life of the shoe. Gemming creates the need for cork filler. That cork is fugitive and will move away from pressure points. Insoles filled with cork are nearly always bare of cork under the ball of the foot. And if the insole is fiberboard or thin, poor quality leather, the insole itself may wear out (developing a hole)...it certainly will not provide any cushioning to the foot nor will it mold itself to the bottom of the foot. Gemming is the cheapest and quickest way to get a shoe together. It literally is the default method for bottoming on the cheapest (think $40.00 a pair) shoes on the market--think Walmart. Even cement construction is a better alternative simply because it is not masquerading as anything other than what it is--quick and easy...and ultimately short-lived. And everyone knows it--you cannot pass off a cement construction as a really high quality shoe.