Design methods may vary, but regardless of the approach taken, several key technical points must be considered.
1. Design must adhere to the anatomical characteristics of the foot when determining the proportions of various upper sections.
If the positioning of upper components on the last is incorrect, the finished shoe will suffer in both aesthetics and wearability. For example, a rear quarter that is too high causes heel chafing, while one that is too low fails to secure the heel. A vamp that is too long digs into the ankle, whereas one that is too short detracts from the product's appearance. A rear-quarter height that is excessive causes ankle bone irritation; an overly long toe cap cramps the toes; a poorly positioned cross-strap makes the shoe difficult to put on; and an opening that is too small hinders entry and risks cracking during last removal. Furthermore, if the junction between the front and rear upper sections does not align with foot anatomy, quality issues such as broken stitching or cracking may occur during walking. Therefore, the placement of upper components must account for physiological foot characteristics and wearability requirements, while also considering factors such as durability, aesthetic appeal, and rational layout.
2. Attention must be paid to the relationship between design dimensions and the actual dimensions of the finished shoe.
While leather shoe production involves diverse materials and manufacturing methods, every design must suit the processing technology and meet consumer needs. Materials used for uppers vary in properties, characteristics, and elongation rates. Crucially, during the lasting process, the upper is stretched into a curved shape; components such as linings, insoles (or half-insoles), heel counters, and toe puffs are inserted between the upper and the last. Consequently, significant shifting of components occurs during lasting. Thus, the dimensions of the upper pattern do not equate to the dimensions of the finished shoe; the latter will be larger than the pattern itself.
3. The relationship between the last shape and the lines of the upper pattern must be handled appropriately.
During pattern design, the interplay between the last's form and the pattern's lines requires careful handling. Through the manipulation of lines on various lasts, the positioning and function of the finished shoe's components must be harmonized with the anatomy of the foot and the shape of the last.
4. Appropriate shoe lasts must be selected during the design process.
Leather shoes fall into two main categories: closed-upper shoes and sandals. Sandals can be further classified into fully open styles, styles with closed front and back sections but open sides, styles with closed toes and open heels, and styles with closed heels and open toes. Closed-upper shoes include slip-on, lace-up, high-top, and low-top varieties; the corresponding shoe last should be chosen carefully during design to ensure the shoe meets standard specifications.