BASIC-Various shoe construction
As we explained in our previous lesson, there are various ways to construct a shoe. The type of shoe constructions we will use will depend on the type of shoe we want to construct, the comfort, and the ability of the shoe maker. There are some simpler ones like the cemented constructions and the more complicated and time consuming ones like the goodyear welt construction. The price of the shoe will depend on the quality of the materials used the time it will take to make the shoe and the level of skill of the technician.
We can classify three major types of shoe constructions which depends on how the upper is attached to the outsole; Cemented, Stitched and Injected/vulcanized.
Lets’ start with the easiest one which is the Cemented construction. As the word says, the upper and lining will be pulled around the last and glued or cemented to the bottom part of the insole. Afterwards, the outsole will be glued to the bottom part closing the shoe. A special glue is used which gets activated with heat so both outsole and lasted upper are placed in a special heated oven to activate the glue and then united together. In some cases, small nails can be added to reinforce the bonding mainly with leather shoes. A press will also help in bonding these two parts forming the shoe.
Second type of construction is where the outsole will be first glued as explained above, then stitched to the upper, lining and insole with a vertical stitch from the exterior to the interior of the shoe. This construction is called the Blake Mackay construction or simply Blake stitching. This will give a added value to the shoe since it will be almost indestructible so long lasting. Some shoes will have a fake sole stitching and so to identify a real blake construction, you can look inside the shoe or in case of a moccasin by bending the outsole or upper. In order to construct a shoe with blake stitching, you will need a patented sewing machine with a double threaded strong needle called Blake sewing machine.
Another type of stich construction would be the Stitched-out construction also called Ideal construction. In this type of constructions, the upper and lining will cover the last but will not turn under the insole and stop on the outer upper side of the insole. The stitching will be vertical as well in two different types. One way is to stitch the upper and lining to the insole, then gluing everything to the outer sole. A second type is the stitching will perforate also the outsole making it much more durable. This type of construction also called flexible construction makes a very casual and comfortable shoe by adapting to the owner’s foot.
A more advanced stitched out construction is called San Crispino where the upper and lining will be stitched as a stitched-out then go under the insole and stitched as well. This vertical stitch will catch the upper at the top edge position, go through the insole and finish at the bottom part of the insole. Once this operation is completed, the outsole then can now be glued. For additional solidity, the outsole can also be stitched to this construction.
Opanka construction is also part of the stitched construction. The sole used for this type of construction is often called a cup sole because of its shape like a cup. The upper and lining will be assembled to the insole just like the cemented construction, then this cup outsole will be wrapped at the bottom and side part, then glued and additionally be stitched horizontally to the upper. This is a more expensive construction so again this stitching could be fake and to see if it is really a opanka construction, we need to see the inside of the shoe. A more expensive version of the opanka construction is when the outsole is made of leather because the leather is more expensive and the sole manufacturer will need special machines to bend the leather in a cup shape.
Finally, we have the Goodyear construction also said the welted construction. This is a very expensive construction because mostly done by very skillful craftsmen by hand. The insole is not flat but has a T section like a lip, so when the upper and lining will curve under the insole and stop on this lip. On the other side of the upper, we have the welt. The stitching will go from the insole lip through the upper and through the welt. The outsole can then be lightly glued to the welt, which will then be stitched just like a blake construction. It is the welt stitched to the outsole which holds it in place. This construction is very elaborated and uses almost no glue so at the beginning the shoe will be heavy and stiff but then will adapt to the wearer and be one of the most durable and comfortable shoes. Because this special insole has lips to allow the stitching of the insole to upper and welt, the middle part will be empty so we will need to fill it with cork past which will harden but still be bouncy like cork.
In all these types of stitching construction there is a channel on the outsole which acts as a guide.
The third family the outsole is made of rubber either natural or synthetic. We have the vulcanize construction and the injection construction. Many sneakers will have this type of construction. In the vulcanized, the outsole is constructed around the shoe by gluing these parts to the upper then inserted in a autoclave where high pressure and hi heat will fuse them together as one piece. Another type of vulcanization is what is often used for safety shoes where the outsole and all its components are placed inside a heated mold, then the upper with heated metal last is pressed on it. The heat for several minutes will bond them together by vulcanizing them together.
The direct injection on the upper construction will insert the upper which is usually constructed as above in a Strobel sock, into melted material. This way we are making the outsole by injecting the compound directly around the upper. We have safety shoes, sport shoes and other type of formal light weight shoes.
FUNCTION: Depending on the type of construction we can obtain various durability, comfort, and functional shoes. As we already said in many occasions, the construction of the shoe will depend on the good quality of all its materials and manufacturers making those materials.
Italian Footwear Solution will utilize all type of construction depending on the final function a particular shoe. We will also ensure to work with manufacturers who are specialized in a particular type of construction. The Comfort and Perfect Fit is our main objective, so each type of shoe will have the best construction to perform that comfort feel.