Does the '5–10mm manufacturing deviation' written in the detailed guide mean that the shoe size changes?

In shoe sizing, 5mm is usually the standard that divides a single size. Therefore, coming across the phrase of a 5–10mm deviation can make one confused about whether the foot size changes significantly. In the detailed descriptions of various products, Blanc Sur Blanc states that an error of around 5–10mm may occur due to the nature of the handmade shoe process^[3][4]. However, detailed standards on whether this figure refers to the foot length itself or is an error encompassing heel height or circumference measurements have not been presented^[5][6].

Handmade shoes differ in process from machine production. Unlike shoes molded all at once by machine, handmade shoes undergo a process where leather is placed over the shoe last and pulled and fixed by hand. Not only does the elasticity of natural leather vary by section, but fine differences also accumulate according to the worker's touch during finishing steps such as attaching the heel and trimming the edges of the outsole. In shoe manufacturing, the manufacturing deviation indicated often encompasses external deviations such as heel height, outsole circumference, or edge margins, rather than the foot length measurement itself.

When choosing a size, it is common to use your usual regular size as a standard. If the foot length itself differed by as much as 10mm, it would be difficult to wear the shoes normally; thus, the indicated deviation can be interpreted as an allowable range for external dimensions resulting from the hand-finishing process of the leather. hmmm, the indication of deviation in the handmade shoe notice is closer to an honest disclosure of the subtle differences that arise while handling leather by hand, rather than a warning that the foot size varies wildly.