With the unwanted product information we may skip the pH Neutralization process mention in post #4.
And we may proceed with this holistic approach with cleaning to removed the unwanted products, rejuvenating the leather for suppleness to control existing cracking and lightening the vachetta leather for appearance.
1 - Cleaning:
The unwanted products has to be removed with Degreaser-2.2 > Acidifier-2.0 system, without using Stripper-2.3 for further drying up the fatliquor content (ionic charged fat and oil) as shown by picture #11. Besides the dried ‘mud cracking’ effect, stitch tears are visible as well that shows weakness of the leather from diminishing original fatliquor. Leather is not allow to be 100% dry at this stage but continue with at least 25% moisture content with Hydrator-3.3.
2 - Leather Rejuvenating:
While the leather is towel extracted after Acidifier-2.0 until towel shows dry or about 25% total moisture content, Hydrator-3.3 further cleans and continues to relax the leather structure, preconditions it for Fatliquor-5.0 for a more even distribution and appearance. The leather is left to slow natural drying.
3 – Leather lightening:
Leather lightening process is with Vachetta-2.8, a pH 2.8 redox (reduction-oxidation) reaction that will lighten up vachetta leathers.
4 – Repairs and Protection
Non-stick draggy-feel protection against sticking soiling and sealing of surface scuff and micro cracking is performed with Protector-D.
>>> The 2 products I'm looking at is Vachetta leather browning removal kit and Vachetta leather tannin remover kit. For my situation, what would be recommended?
With reference to the above holistic sequence of process and products systems mentioned are found in this Kit-V4
http://www.leatherdoctor.com/kit-v4-...g-removal-kit/
Leather Doctor® Kit V4 specialty problem solving kit include Vachetta-2.8 for browning removal and Degreaser-2.2 for body contact decontamination systems in a holistic approach. Kit V4 is a combination kit from Kit V3 and Kit V5.dr without duplicating of products for these common related problems.
Darkening appearance from body contact and browning from liquid stain are two main inevitable common problems associated with naked unfinished vachetta leathers. Leather being absorbent absorb and accumulates body moisture from contact and when neglected resulted in a darkening appearance. Besides appearance the sweat with traces of urea may cause the protein fiber from shifting ionic negative (-ve) manifesting as tackiness and reverting to rawhide.
Degreaser-2.2 solves the darkening effect by penetrating, lubricating and suspending the soiling particulates and simultaneously protonate the protein fiber ionic positive (+ve). The amphoteric protein fiber is further rinse and ionic positive (+ve) charge with Acidifier-2.0 to strengthen the ionic attraction between its other non-amphoteric ionic negative (-ve) leather constituents like the tanning agent and the fatliquor. This dual duty removes the unwanted soiling particulates and pH balance the pH chemistry integrity of the leather at the same time.
Leather rejuvenating is mandatory and comes next when appearance become satisfactorily. This is accomplished with Hydrator-3.3 > Fatliquor-5.0 system. Hydrator-3.3 plays a significant role in absorbent leathers like vachetta where stains are usually penetrated. The hydrator’s surfactancy helps internal leather structure colloidal movement by moving suspended soiling particulates to the surface at each wicking process until exhausted and is often used as part of the rinsing process. Besides hydrator is used to check for surface tension and relax the leather fiber prior to ionic negative (-ve) charged Fatliquor-5.0 replenishing. Natural slow drying in between application until saturation produces a softer leather.
Browning of vachetta leathers is associated with alkaline over-exposure, vachetta being a lower pH value than most other tanned leathers averages pH 4 is more sensitive to alkaline cleaning or stains and even water at pH 7 will cause discoloration and browning. Another browning or seasoning effect is associated with UV lights typically exposed to sunlight, just like our light colored skin being sun tanned. Yet another browning association with unknown products absorbed and even too much moisture content will affect the appearance one or two shade more intense just like the color of the clouds. To keep the leather supple with softness and strength from developing cracks, a well season (up to 14% of fatliqiuor content) leathers is highly recommended over appearance. Vachetta-2.8 with its low pH works by oxidation-reduction reaction to reduce the discoloration or browning effect to a more even appearance when the leather is left to dry naturally.
Protecting the leather with Protector-D impart a natural draggy-feel and reduces wear to the grain of the leather, conceal scuff with its healing properties that also allows transpiration to take place or breaths naturally. Note that the mentioned products suffix numbers denotes its pH value in this holistic approach to removing the common problems associated with vachetta, saddlery and veg-tan leathers.