To maintain a beautiful shape for a shirt collar, an interlining must be inserted inside to give the fabric firmness. There are two ways to do this: "fused interlining" and "non-fused (floating) interlining." It is said that 90% of shirts in Japan use fused interlining.
Fused interlining refers to a method where the interlining is semi-permanently bonded to the fabric using an adhesive. While it has the advantage of making care easier, the collar becomes stiff, causing the fabric to lose its natural texture.
This is why Shuttle Notes shirts utilize non-fused interlining.
The soft texture of a traditional non-fused collar cannot be replicated with fused interlining. Furthermore, the comfort of how it contours to the neck is incomparable.
Non-fused interlining is an inefficient construction method that can only be executed by factories with highly advanced sewing techniques. We choose to use it nonetheless because we want to create a first-class product, not just in terms of fabric, but also in construction.