This is a tanning process which uses aromatic polymers such as the Novolac or Neradol. This process came to be invented during the time of World War II, when vegetable tannins were in extremely short supply.
The leather resulting from this process is white in colour. Melamine and other amino-functional resins fall into this category as well. They often provide the filling that modern leathers require.
Like with aldehyde tanning, Urea-formaldehyde resins were also used in this tanning method until the spreading awareness of the dangers of formaldehyde was realised, and the process was adapted to exclude it.