20’sと30’sと40’sの506XX
同じ品番だけど違う年代

（襟）
20’sの頃はまだ襟に角度が付いておらず四角になります。着用するとワイドスプレッドの様に横に広がるのが特徴です。
30’sになると襟に角度が付いてるのが確認取れます。生地の地の目は20’sと40’sが同じなのが確認出来ます。
因みに20’sの襟、生地を捲らないと見えないですが耳使いになります。

■Collar
In the 20’s, the pattern of the collar was still a complete rectangle. When worn, the collar goes wide spread and how the collar looks is very archaic in a good way, which you rarely see in the clothings of today. After the 30’s, the cut pattern was revised and the collar sits with some angle.
There’s one more interesting detail in the weaving direction of the fabric used on the collars. If you look at the collars on the 20’s & 40’s jacket, the fabric was cut vertically whereas the collar on the 30’s jacket was cut laterally. When the jackets are in a new state, it might be difficult to tell the difference but it’ll be obviously different once faded. By the way, the selvedge is used only on the collar of the 20’s JK but it’s hidden underneath so that you can’t directly see it though.

（スクエアステッチ）
プリーツを留めるスクエアステッチも年代でバラバラです。（もちろん個体差は有ります。）
20’sはとても細い四角30’sは少し大きくなり私が所有する大戦期の40’sはとても太い四角ですよね。大戦が明けるともう少し細くなる傾向が多いと思うので面白い所です。

■Box pleats stitching
They vary greatly and it has a wide range of individual differences. If you look at the vintage jackets, 20’s has very narrow ones and they become wider and larger on the 30’s, and they go much wilder, even misaligned, on the 40’s. After the 40’s, the size and the width of the box pleats become narrower again.

（ボタン）
20’sに使ってるボタンは501で言う所のボタンフライに使われる小さいボタンが採用されております。
30’sになると現在と同じ大きさのボタン。40’sは月桂樹のドーナツボタンになります。

■Buttons
The fly buttons, the smaller ones, are used on the 20’s Jacket. On the 30’s Jacket, the button size become the same size as the standard ones. In the 40’s, the buttons are of the laurel wreath without the brand name because of the regulations on the manufacturing under the time of war.

（ポケット）
ポケットの大きさはサイズがバラバラなので比較にはになりませんが…。
まずミシンの入れ方です。ポケットを付けるのはどの年代も二本針ミシンを使ってると思うのですが20’sは角を止まらずに回るため内側の軌道が無理矢理になってます。でもこのステッチの乱れがこの年代の魅力では有ると思います。
30’sと40’sはミシンを一度角で止めて角度を変えて縫ってるため内側に三角のステッチが発生してます。
フラップも面白く20’sは丸く30’sになると角が出ます。縫い方も20’sの頃は1本針で縫われてます。30’sになると二本針でポケットとフラップの糸を切らずに縫製してます。40’sは国からの指示でフラップの存在が有りません（涙）
写真に収めてませんが20’sのフラップ裏は同じ生地30’sのフラップ裏はライトオンスになります。
レッドタブがまだ付いてないのも20’sの特徴です。

■Pocket
The pocket size depends on the size of jackets so we’d like to focus on talking about the sewing details here.
When it comes to the stitch work on the front pocket, the two-needles machines were used for the 20’s ~30’s Jackets so that the distance between the two stitches should always be the same regardless of the skills of sewing person. But in the 20’s, I assume that the two needles machines that can lift up either of the needles were not developed or they were not prevalent yet. As a result, the sewing pitch of the inner stitch at the corners gets finer because you need to forcefully sew the corners, which I think is one of the interesting details. On the other hand, looking at the same pockets on the 30’s or S40’s Jackets, the sewing machines developed. So, it became possible that we stop right before sewing the corner, lift one of the needle on the inner side, change the direction nicely, and then put back the needle again. As a result, you can see a nice little triangle at the corners.

Speaking of the flaps, the stitches on the flap on the 20’s Jacket are more roundish but they are more sharply sewn with an angle on the 30’s. On the 20’s, the sewing was done separately between the pocket and the flap but on the 30’s, they were done in one-go, which you can see if you see the back side of the flap. The 40’s jackets don’t have the flap again because of the said regulations.
Some might find it sad but 20’s Jacket didn’t have the iconic red tab yet.