Leather Rejuvenating BMW Z1 from 1990 – leather condition is very dry becoming flat, but now, after hydrating and fatliquoring, the leather have become significantly softer and “plump”.

I am in the process of restoring the leather interior (door panel, dashboard, and various trim pieces of a BMW Z1 from 1990. The leather condition is very very dry, becoming flat (2Dimensional), but overall in good condition, i.e. no crack or tears.

I did not take photos of the before condition, but now, after hydrating and fatliquoring, the leather have become significantly softer and 'plump',

My further question:
When should I stop fatliquoring?
What is the sign of too much fatliquoring?
As with some trim pieces, it appears that they keep absorbing the fatliquor.
After all the process is done, will the restored leather be as good as new leather in retaining the fatliquor, or will I have to replenish the fatliquor often?

>>> When should I stop fatliquoring?

When the moisture level reads up to 14% with a moisture meter when the leather is dry to the touch.


>>> What is the sign of too much fatliquoring?

When it is up to 14% (modern tannery standard) or becoming too soft and it may spew out when the leather becomes too cold below 10 degrees Celsius. This cloudy or milky appearance can be reactivated with a warm hair dryer or clean off with d’Spew-4.8. See: http://www.leatherdoctor.com/servlet...pew/Categories


>>> As with some trim pieces, it appears that they keep absorbing the fatliquor.

Vegetable-tanned leather is more thirty for fatliquor, while chrome-tanned leathers need less for the same softness.
A moisture meter reading when dry will determine its condition.


>>> After all the process is done, will the restored leather be as good as new leather in retaining the fatliquor, or will I have to replenish the fatliquor often?

This is a fatliquoring process similar to the modern tannery process where the ionic negative (-ve) fatliquor is hydrogen bonded with the ionic positive (+ve) leather protein fiber. One purpose of Hydrator-3.3 with a pH value of 3.3 helps protonate the amphoteric protein fiber by increasing the ionic attraction between them, just like magnet unlike poles attracts. Fatliquor is a volatile organic compound, same as the tannery original will evaporates as gases and will require periodic replenishing – similar to our car engine oil that require frequent top up as well.

It would be better if you show some pictures of your concern, answers given are general and may not be specific to your peculiar situation. An objective answer relies on a moisture meter.

Roger Koh
Leather Care Consultant
www.LeatherDoctor.com


Roger Koh
Leather Care Consultant
www.LeatherDoctor.com