Full-grain leather is regarded the top level of smooth leather, however they can be divided into two grades further: full aniline-dyed and semi-aniline-dyed.
(Full) Aniline Leather
Leather with the best quality and the least processed content comes from cattle with rich sebum oil, and the leather does not need to be over-processed.
The dyes used are mostly pure natural plant dyes without any pigment.
Aniline was used to dye the whole leather with the same color, and the whole leather was dyed by low temperature dip dyeing. Aniline dye can penetrate into leather without changing the surface texture or destroying the natural protective layer on the surface.
This kind of leather is called aniline leather.
(Full) Aniline-dyed leather is the most attractive in texture, and its skin-friendliness and meticulous touch are unparalleled. Cowhide is dyed in the drum, and the surface layer is hardly colored or treated, so the pores and surface texture are clearly visible.
(Full) Aniline-dyed leather is usually expensive, mainly because it is not easy to obtain the crust leather. Because there is no grinding treatment, when selecting the cowhide, the fewer defects, the more expensive it is.
Semi-Aniline Leather
The cortex of cattle’s complete pores is preserved, but it still needs to enter the whole skin soaking and dyeing process to make the whole body more shiny.
Although semi-aniline leather is not completely natural, it still retains the natural touch of cowhide after slight processing. There is surface coating while it is not excessive though.
Semi-aniline dyed leather not only has a natural texture close to aniline leather, but also has a protective effect on the surface after surface treatment, which can be said to be the most popular high-end leather on the market at present.
Summary
My love to dress shoes drives me to find out what grade of leather they are using, the answer is semi-aniline. The choice is probably based on scratch-resistance.