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Shoemaker's story #09 | About materials, sole edition

Blue over sample craftsman. The shoes are made by hand, from the pattern to the sewing and shoemaking. We also handle factory arrangements and material setup.

This series is a compilation of several notes I wrote in order to explain my work, namely making shoes, as clearly as possible.

About insoles

What is sole?

Sole is the general term for the bottom of a shoe.

The sole is mainly divided into three parts .

  • insole
  • midsole
  • outsole

All of these words come up often in our blueover, so I would like to have the opportunity to explain them one by one.

And today is the insole.

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You may be more familiar with the term insole . It comes into direct contact with the foot inside the shoe, acting as a cushion that protects the foot from impact when walking, improving the fit of the shoe, and supporting the foot.

our insoles

At blueover , we mainly use two types of insoles.

The first is a cup insole made of leather, the same material as the lining, laminated with felt fabric and partially covered with urethane. It is used in models called marco and PHOLUS.

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The second is a flat insole made of low-resilience urethane laminated on the back of a canvas fabric with the brand name printed on it.

I'm printing a lot of blueover, blueover, blueover, blueover.... Used in mikey, bobbed hair, and some SHORTY TRs.

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We ask a domestic insole shop to make our insoles.


No matter what type of shoe you have, even if the insole has too much cushioning, it can also make it difficult to wear. Please keep this in mind when fitting. *When trying on shoes, be sure to walk around the store with both feet on! !

We recommend choosing shoes that have good moisture absorption properties to absorb sweat from your feet.

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Also, if you use your shoes for a long time, you may find that the insoles start to sag and you want to replace them. You can purchase them at 100 yen shops or Tokyu Hands, but if you consult with the shoe brand, you may be able to purchase new insoles from the brand's official brand. (Maybe around 1000 yen to 2000 yen.)

About midsoles (Part 1: From a sneaker perspective)

Today we're going to talk about midsoles. This will be long, so I will write it in two parts.

What is midsole?

It is located inside the outsole, midway between the upper and outsole. Although the name is true, sneakers and leather shoes give a slightly different impression.

Midsole perspective from sneakers

It absorbs the shock that is applied to your feet when you walk, reducing the burden on your feet. The key to midsoles in sneakers are cushioning, resilience, lightness, and durability.

The white part of the sole in the photo below is the midsole.

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History of sneaker midsoles

In sneakers, the midsole runs from the toe of the shoe to the heel. The impression is different from the midsole of general leather shoes.

This specification was developed in the late 1960s and 1970s, and along with it, EVA (ethylene vinyl acetate copolymer resin), which was highly cushioned and lightweight, was born and evolved. Ta.

Since then, the development of cushion materials other than EVA is also progressing. A revolution has occurred in sports shoes.

What is EVA?

At blueover , we use EVA .

It has more flexibility and elasticity than polyethylene. Also, compared to urethane, it is less prone to deterioration. (*Urethane may change over time due to moisture, but if you handle and store it carefully, you can make it last longer.)

When you open the shoes that you have stored in a shoe box for the first time in a long time, you may find that the soles are crumbly or sticky.This is called hydrolysis. EVA does not undergo hydrolysis.

It is a material that does not harden even in cold places, has excellent durability, and does not deteriorate even when exposed to wind, rain, and UV rays. It also has a low specific gravity and is extremely light compared to vinyl chloride and rubber.

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In the SHORTY TR from one season ago, colored EVA was layered on the EVA part to play with color.

blueover EVA

Hardness can be adjusted by adjusting the EVA composition. At blueover, we design our shoes to be just the right hardness for everyday wear and street wear. They may seem a little stiff compared to running shoes.

In order to reduce fatigue when walking for long periods of time, the hardness is slightly higher and the shoes have more rebound than running shoes.

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A processing sole shop in Japan cuts the EVA sheets and outsole sheets one by one, glues them together, and carves them out. This is a very time-consuming process. Our shoes are made with the support of many people.

About midsoles (Part 2: Leather shoes perspective)

Yesterday we talked about the first part of midsoles. From a sneaker perspective, it was on the outsole. Today I would like to talk from the perspective of leather shoes.

Midsole for leather shoes

It might be a bit of a misnomer to say it's from the perspective of leather shoes. The midsole that I would like to explain here is deeply related to the bottom seam of the shoe .

sewing the soles of shoes

There are many methods for making shoe soles. Many Japanese brands use a cemented manufacturing method. The upper part of the shoe, called the upper, and the outsole are bonded together using adhesive. (More details will be discussed in another session.) This method does not involve sewing the bottom .

There are other manufacturing methods, such as the Goodyear manufacturing method and the Mackay manufacturing method, in which the bottom is sewn after the upper part and outsole are attached. Many shoes with leather soles, especially those with sewn soles. It also prevents the bottom from peeling off and adds to its cool appearance.

Second sole/triple sole

Some shoes have a piece of leather or rubber sheet sandwiched between the upper and outsole when sewing the bottom to make the entire bottom thicker. Tricker's is manufactured using the Goodyear method, but the midsole is sandwiched between the thin leather called welt that wraps around the upper and the rugged outsole , and is sewn in three layers.

The result is a shoe with a solid feel and presence.

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When I was working as an individual before joining blueover, I only made shoes with leather soles. At that time, I was sewing the bottom using a method called Black Lapito. The method was to sew it out after making the muckay, and the midsole was essential at that time.

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The photo shows shoes from that time. I like how the midsole adds volume to the bottom. Leather soles also add durability and water resistance.

However, compared to a single sole with only one layer pasted on, the entire sole feels harder. The ``burr'' is inferior to single soles, so single soles are better in terms of foot comfort.

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The dashi stitch is a bottom stitch all the way around the upper, as shown in the photo above.

Midsoles commonly found in boots

This is often seen in work boots, etc., but sometimes the midsole is glued together, the bottom is sewn, and then the rubber outsole is glued on. In the photo below, the welt and midsole are sewn together in two layers, and the outsole is glued.

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blueover midsole

Blueover has models using the Mackay manufacturing method and the Goodyear manufacturing method, marco and PHOLUS.

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marco uses the Mackay method to sew the midsole and then glues the outsole.

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PHOLUS is made using the Goodyear manufacturing method, with understitching and outstitching, and then the outsole is pasted on. Both have a sewn midsole and an unsewn outsole, which is glued together.

Even though it's a sneaker, the midsole and bottom seam are used so that when the outsole wears out, the sole can be replaced without affecting the upper. The midsole allows you to change the sole without touching the upper.
We have adopted this product with consideration for long-term use.


Midsole, which I talked about twice. I think the content was a little difficult, but I hope you understand.

In summary, at blueover, we use both EVA midsoles from the perspective of sneakers and midsoles with bottom stitching from the perspective of leather shoes.

We would like to continue to seek out better shoes in the future by taking advantage of the merits of both past and new technology.

Until the outsole is made

Mainly, there are two types of outsoles.

Although there are many different materials, there are two main types of outsoles used during mass production.

  • molded bottom
  • Processed bottom

An exception would be things like custom-made shoes. In many cases, each bottom material is cut out and processed at the same time as the bottom attachment work, so there are cases where neither of the above methods can be used.

What is a molded sole?

Molded soles are made by pouring a material (rubber, urethane, EVA, etc.) into a mold shaped like the outsole, then baking or inflating it. Molds are often prepared according to design and size, and although the initial cost is high, production efficiency is high and a large number can be made in a short period of time. The soles of boots and vulcanized shoes are also types of molded soles.

Although it's not Blueover, the women's shoe brand I founded called AROA uses the same urethane molded soles used in nurse shoes. When you order the bottom from the factory, it will be ready quickly compared to the processed bottom. There is no problem with the cushioning properties.

Materials are often made from one material. (There are also shoes that have several parts made from molded soles glued together. It reminds me of Reebok's Pump Fury.) It looks like it was made from about 3 different materials and several parts put together. )

Vibram's famous sole unit #1136 is also a molded sole (though the material is a brand-specific combination called VibramTront).

What is processed sole?

The outsole used in blueover is a processed sole.

The outsole here refers to the unit that the sole factory recognizes as the sole material. The EVA parts of the sneaker sole are sometimes called the midsole, and the rubber is sometimes called the outsole. I previously explained the midsole and outsole separately.

There are many types of processed soles. Making a leather sole unit is also a processed sole.

This time, we will introduce the process of making our processed soles along with photos.

①Create a cutting die for each type and size of the shoe sole design and cut out the EVA sheet and rubber sheet. Cut in the same direction so that the pattern on the rubber is the same. While also thinking about how to handle it.

② After performing an adhesion test, attach the EVA cut in ① to the rubber. If there is a wedge (heel), the EVA seat is slanted or two sheets overlap so that the heel is high and the front is thin.

③Depending on the gauge of the outsole, remove the excess with a buff, clean the sides, and add an angle (flare angle). Much of the work is done by hand, and the skill of the craftsmen shines through. Each item requires a lot of effort, so delivery times are long.


The outsole has a very strict design, both molded and processed . If it is too large even by 1mm, the feeling of the adhesive will be misaligned when attaching the sole of the shoe. Of course, the results will also change.

Therefore, when making bottom samples, it is necessary to have detailed discussions not only with the processing sole shop but also with the bottom attaching factory. Since each bottoming factory has different habits, we will consult directly with the factory requesting mass production. I made samples, bottomed out, made samples, bottomed out, and repeated the process over and over again.

We are finally adopting it in a new model.

Well, what do you think? I'm currently looking for a new outsole. The first sample finally came out about 4 days ago, and although it still needs some modifications, it looks like it's going to be very good.

We are looking forward to seeing you in the spring, so please look forward to it.

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