Synthetic tanned

Synthetic tanning is frequently used as an alternative to chrome tanning.

Synthetic tanning agents (aromatic syntans) are produced artificially, so have no counterpart in nature. Examples of these include formaldehyde, glutaraldehyde, phenols and acrylates. The synthetic tanning method is not employed as an isolated tanning process, but mostly as part of a combination tanning process with either chrome tanning or vegetable tanning. Chrome leather production ensures retanning with synthetic tanning agents as they provide the necessary “fullness" to the leather. It is estimated that annual production of synthetic tanning agents amount to 200,000 tonnes (2008).

After tanning, when the leather is still wet and not dyed, it gets a bright colour and hence is also referred to as wet white.

Synthetic tanning agents - Wet white

A disadvantage of chrome-free (FOC) synthetic tanned leather is its sensitivity to moisture in the leather, plus heat. Approx. 50% of all car leather is FOC. If a convertible is rained on, a liquid runs out and if a wet towel or a wet swim suit remains too long on the leather, moisture migrates through the finish, the seam holes or the perforation holes. If sun shines on such wet leather, the matrix water (chemically bound in leather) starts boiling and the leather hardens and shrinks.