Worth knowing about leather

Core leather:

The oldest and most natural leather form. Core leather is strong, durable, often untreated leather with the "right" leather touch. Used mostly for expensive designer furniture, where the leather is often uncoloured, such as Børge Mogensen's Spanish chair. May be dyed with a color which penetrates the leather, and may be waxed.

Aniline leather:

Core leather that is treated with color and softened. Natural soft colored leather without surface protection with the "real" leather toe. Aniline leather is often found in the expensive end of furniture, i.e. Arne Jacobsen The Egg and the Swan. Aniline leather is very susceptible to stains and it is recommended to treat with leather grease. It is the type of leather that continuously gets a beautiful patination.

Semi-aniline:

Is dyed as aniline leather but has a lighter coating / cover layer to make the leather more durable. Semi-aniline can behave either as aniline leather or colored leather. In simple cases like both and cover-colored leather on seating surfaces and as aniline leather on the sides of the furniture.

Cover colored leather:

Cover-colored leather is the most common type of leather and is sold under many names. Cover-colored leather has been given a strong surface protection or cover color. It is more stiff, completely smooth and can be shiny. Cover-colored leather is very resistant to spills and stains. It is leather which over time becomes worn and crackles and is used for e.g. Arne Jacobsen 7s chairs.