1] Seats feel like cardboard.
This cardboard stiffness is due to diminishing of original fatliquor (ionic charged fat, oil and water). Fatliquor diminishing through evaporation as VOC (volatile organic compound) and leaching through breaking of hydrogen bonding; where a non-leather-safe alkaline solution is used and by degreasing with solvent contents solution like alcohol. Caution is to check the products used; its pH value and its alcohol contents, as the usage of such products will further harden the leather when dry.
Leather protein fibers shift poles and if a pH value of a cleaning solution is above the isoelectric point of the leather it will shift the protein fiber negative (-); all other leather constituents are mostly negative in nature too; thus the other constituent especially the more sensitive ones like the fatliquor will repel like magnet “like poles repel” and leach out during cleaning. When dry without the fatliquor that separates and lubricates the individual fibers acting like millions of connecting hinges becomes stick-together and the result may be stiffer than before.
Pure solvent will be without a pH value, most alcohol cleaners will still have a pH value; and if the pH is alkaline it will make the leather even stiffer when dry.
The answer to this leather cardboard stiffness is using “leather-safe” cleaning strategy with hydrating to relax and separates these stick-together leather fibrils prior to fatliquor replenishing it.
Why is it so?
This original non-absorbent leather now behaves just like aniline absorbent leather found commonly in the Ford King Ranch.
What solution used will affect the secondary leather structure, which will cause further denaturing of the leather by breaking of hydrogen-bonding and leaching them out.
We are no more just cleaning the mere coatings of the leather anymore; but the leather itself.
2] Seem to be a bit darker than other Volvos of same year (REALLY dirty?); Should I just scrub away with a scrub brush?
Scrubbing is done with the “physical mechanical action” sure contribute to the result; but should caution of doing over its threshold (most novice may be oblivious) and may cause more damages to the texture.
The ideal cleaning technique is to utilize contribution from these 4 factors, Chemical, Heat, Physical Action and Dwelling-Time:
A] Chemical – Leather-safe is using product range that has a pH value of between 3 and 5 (that is also the neutral pH of leathers); another consideration is the strength of the product and it can range from a prep-cleaner to super-cleaner to strong-cleaner to cleaner. In this situation is recommended to use a prep-cleaner within the pH of 3 and 5.
B] Heat – Heat is recommended to be done at room temperature, although the power of cleaning may double at every increment of 18 degrees; excessive heat may further shrink the leather causing lost to the fatliquor; resulting in further stiffness when dry.
C] Action - Scrubbing sounds too harsh for leather, agitation sound more like it; it is recommended to use a horsehair detailing brush and limit suedeing to the leather exposed grain.
D] Time - Products instructions that emphasize on dwell time usually works by “Penetration, Lubrication and Suspension” – you have paid for the products, shouldn’t you allow the products to take its time to do the dirty work safely for you instead?
3] What is the best (most efficient, safest) product to use?
Everyone will swear to you that the products they have mentioned works!
Anyway these are the general structure sequence of structural and finish restoration for your consideration.
Leather-Safe-Restorative-Cleaning > Hydrating > Fatliquor-Replenishing > Wet-Prep > Dry-Prep > Adhesion-Coating > Pigment-Coating > Topcoating > Rub-Resistant-Protection
“I haven’t worked on a car that is this age and this level of filth.”
And if this is your first attempt; you want to make sure you “Do It Right the First Time”.
You need to borrow someone’s “hindsight to become your foresight”.
Roger Koh
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