It is very unlikely that the topcoat stays intact if the cleaning is done from the smooth surface that we see.
If done on the suede side may reduce damages to the finish, but looks like there is no way to reverse the leather, do you?
To get the penetrated oil, grease and perspiration out would require a deep degreasing, probably all the way through the thickness of the leather.
This degreasing process is done by using an acidic water-based pH 2.2 degreaser both to remove the contamination as well as for bleeding control follows by either a pH 3.0 or 2.0 rinse to stabilize the chemistry of the leather.
In situation where perspiration is concern, it is more damaging to the leather than merely the oil or grease.
Leather protein fiber is amphoteric; that is, it will either shift ionic positive (+ve) below or ionic negative (-ve) above its isoelectric point of pH 4, depending on the influencing prevailing pH. In this situation, the pH would have shift alkaline (more than 7) when perspiration ferments. When ammonia smell is detected, the contamination pH would shift to almost pH 10 and shifting the protein fiber ionic negative (-ve).
Leather protein fiber may shift from ionic positive (+ve) to ionic negative (-ve), but the other leather constituents like the tanning agent, dyestuff and fatliquor remain consistently ionic negative (-ve).
When protein fiber shift ionic negative (-ve), it repels the other ionic negative (-) leather constituents, behaving just like magnet; “like poles repels”. Stickiness result when tanning agent breaks hydrogen bond with the protein fiber, bleeding result when dyestuff breaks hydrogen bond with the protein fibers and stiffness result when fatliquor breaks hydrogen bond with the protein fiber.
I will continue the recommended sequence of process:
Roger Koh
[email protected]