Keeping the leather clean is referring to the leather finishes maintenance for aesthetic, appearance or look, basically this finishes is a soft and strong urethane coating over a pigmented coating; and assuming that this coating is also non-pervious as micro creasing may have not developed yet, fully molded without seams or stitching holes, and non-perforated. Yet if you take a surface reading of it pH value, it will still shows that it is acidic, below pH 7. The leather structure reading from the reverse side will probably average between pH value 3 and 5. So we are still talking about “coated leathers”. In most cases you’ll see “uncoated leathers” in “coated leathers”. And it is these “uncoated leathers” areas that begin to manifest into the “coated leathers” that wakes up the owners. Have you take a close look at stitching holes to monitor the health of your leathers. The original needle holes at its prime health should be a perfect round. Original fatliquor evaporates or leaches out at these weak points and these are the areas where leather rejuvenating is all about, keeping the leather with perpetual suppleness and strength is to have a periodic top-up of fatliquors from a bottle. A slanted needle holes when wet and dry again will be stiff and when flexed will develop into cracks.
Most of leather care products are waterbased and will have a pH value when read with a pH meter. Cleaning products that have a reading between 3 and 5 will be leather safe both to above surface and below surface. So an acidic cleaner is safer than an alkaline cleaner. Acids will contracts the finishes tighter, while alkaline will wedge the surface and weakens it. Alkaline cleaners may streaks the topcoats and yellow it when compare to acid cleaners; that’s why such non-leather-safe cleaners’ instruction is to foam cleans it, to reduce the inherent streaking possibility. Leather-safe cleaners can be applied any how you wish and yet will not streaks the finishes.
Solvent or alcohol contents are never wise to be used to “keep them clean”. It’s used primarily to remove oily soiling with its solvency. Bad for finishes too as it weaken it, thus a heavy conditioner is used to hide the damages. Keeping them clean with alkaline solvent content cleaners will erode the original OEM finishes and replacing it slowly with weaker alternatives.
“So it seems that the key is being sure to keep them clean.”
So besides the pH value of products used, acidic or alkaline with solvency; the next consideration is to check its residue contents, and this is a testing recommendation.
If you apply your chosen product to your glasses (spectacles) or glass panels, see if you can clearly see thru it; if you can’t, that is not the right product to use on your leather as the residue will accumulate and distort the leather original appearance; besides all the grooves and stitching holes and perforated holes will be filled with these unwanted residues.
Leather Conditioner above Surface.
Since the modern OEM topcoating is such a soft and strong protection over the colorcoating; is it necessary to further condition to coats it?
Check the ingredient of conditioner or protector and ask yourself, is this protection stronger than the OEM topcoat?
Yes it could be a useless layer that begins to attracts more soiling – apply such conditioner or protector over a plastic sheet and test it out to verify what I have said.
But we also have seen finishes wears out with friction rubs very common on booster that we slide in and out.
To reduce such friction wears a “rub-resistant” protection will be most ideal, that impart a buttery feel without the leather sticking to our body especially when wearing shorts that also reduce overstretching the leather too; would be of benefit to the finishes worth considering.
Leather Conditioner below Surface.
The below surface conditioning takes care of the chemistry integrity of the leather, that provides us with practical usefulness in suppleness and strength. As the leather ages with diminishing fatliquor it need to be periodic replenish just like periodic checking and topping up of our car engine oil. Products that caution on applying on suede are questionable. What is suede, it’s the reverse side of leather; rather the needle holes and the perforated holes are suede from the cross section. Leather suppleness is derived from the millions of connecting fibrils working together like a long chain of hinges; and each has to be separated and lubricated for it to be compress and stretch when flexed. Much of the leather suppleness depends on the fatliquor (ionic charged fat, oil and water). The lifeblood of leather, the fatliquor now comes in a bottle. Different between rejuvenating oil and fatliquor is first its appearance; oil appearance looks no different from cooking oil; while fatliquor appearance looks no different from fresh milk; and there are some conditioner that looks in between cooking oil and fresh milk. So you may have 3 level of conditioning to choose from, all will soften the leather to a degree.
Oil:
These are the traditional stuffing oil that fills the inter-fibrillary spaces; retards transpiration; darkening effect; yet contribute to softening the leather. Pour it onto a clear bottle, will remain stable in appearance.
Popular Conditioner:
Instructions cautions on applying to suede, sulfuric fragrance that tends to yellows; yet contribute to softening the leather. Pour it onto a clear bottle, you will see the separation of the oil to the surface - pretty unstable.
Fatliquor:
Its ionic negative charged (-) fat, oil and water that is design to hydrogen-bond with the positive charged (+) leather protein fibers for a more lasting effect. Fat contents plumps the leather with fullness, Oil lubricates the individual fibrils for suppleness and the water that encase these fat and oils evaporates to leave the leather with the desired transpiration. It’s the universal conditioner for all leathers including nubuck and fine suede with no darkening effect and the classic leather scented fragrance to choose from. Pour it onto a clear bottle, looks like fresh milk and remains stable even chilled from fridge.
Try all of these classes of conditions to experience the difference – you would find the good from the bad and knows the ugly ones too!
Roger Koh
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Right now, I'm not in the market for any leather conditioners, but just wanted to point this out.