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Thread: Restoring and restaining 17 year old Nubuck leather couch

  1. #1
    Join Date
    Sep 2017

    Default Restoring and restaining 17 year old Nubuck leather couch

    Roger - I am looking to restore my 17 year old Nubuck leather couch set, which has various kinds of stains, scratches, color fading etc. The leather itself feels supple to touch, and does not have any cracks or peeling.

    I tried to hire leather restoration professionals locally, but most of them declined to accept the work, or were not experienced enough handling Nubuck leather to confidently predict positive outcome for the effort.

    I stumbled upon your site, and forum, and am impressed with your scientific approach and positive results that other members of the forum seem to have achieved.

    I am planning to start with the smallest piece, completely restore, and stain it to a darker color.

    Here are the details with pictures -
    Soiling type:
    6. Accumulative

    Stain type:
    7. Penetrated oil, grease and sweat on all pieces
    10. Protein based: Milk, body fluids (urine on 1 piece - abt an year old)
    11. Tannin based: juice

    18. Urine
    19. Sweaty

    Finish problems:
    22. Sun fading
    24. Nap renewal (?)

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  2. #2
    Join Date
    Feb 2007
    Greater Vancouver, Canada.


    Use this Nubuck Problem Solving Guide to solves your multiple problem.

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    Basically in a restoration cleaning there is a combination of “Dry-Process” and the “Wet-Process”.

    A- “Dry-Process” would include dry soil removal with nubuckBrush-2 in combination with leatherEraser-4 and vacuuming, and after the “Wet-Process” that ends with with a “Dry-Process” by renewing the nap again with brushing, erasing and 320grit sanding if necessary to even out the nap. Then final “Dry-Process” is after Protector-S/S+ for a “finger-writing-effect”.

    B- “Wet-Process” is to follow the Matrix/Guide sequence of process accordingly. Various “Soiling” type, “Stain” type and “Odor” type may be combine one after another before introducing Hydrator-3.3 > Fatliquor-5.0 Hydrator-3.3 system.

    C- Examples of “Wet-Process” combination of sequence before Hydrator-3.3:

    Order Problem #18 Urine and #19 Sweaty may use the same process as sweat has a trace of urea as well.
    Thus the sequence is as follows:
    CleanPro-1.5 > Acidifier-2.0 > KillUrine-2.1 (wait till it dries to inspect the odor - otherwise repeat until odor dissipate).

    “Stain” type problem of #7 (Penetrated oil, grease and sweat on all pieces) and #6 (Accumulative soiling) is combine clean with:
    Degreaser-2.2 > Acidifier-2.0 > Hydrator-3.3.

    “Stain” Type #10. (Protein based: Milk, body fluids) removal is by:
    CleanProtein-9.9 > Acidifier-2.0 and leave dry, any fermenting odor is treated with KillBacteria-3.7 and leave dry.

    “Stain” Type #11. (Tannin based: juice) removal is treated with redox (reduction-oxidation) reaction with CleanTannin-3.5 when dry and leave to dry to inspect for result.

    D- Examples of “Wet-Process” combination of sequence for the Hydrator-3.3 > Fatliquor-5.0 > Hydrator-3.3 system:
    When all soiling, stain and odors are taken care of satisfactorily the leather rejuvenating process begins with Hydrator-3.3 > Fatliquor-5.0 > Hydrator-3.3.

    E- “Dry-Process” again to remove surface wick-up soiling and the above (D) may be repeated until all soiling and stains is resurfaced to be physical removed by brushing, erasing or sanding.

    F- Protector-S/S+ is applied.

    G- Brushing to raise the nap for a “finger-writing-effect”.

    Let me know if you have any questions.

    Further readings on the urine killer kit, other mentioned products are available as individual items

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    Leather Doctor® nubuck urine killer kit is specially formulated to decontaminate urine problems. Aged urine is detectable with its characteristic ammonic odor. The presence of ammonic odor may indicate the shifting of pH value up to 10. The leather will most likely feel sticky or slimy when wet finger testing it. This sticky feeling is a sign of leather denaturing and reverting to rawhide. Stabilizing this sticky phenomenon is done with pre cleaning with CleanUrine-1.5 follows with Acidifier-2.0. KillUrine-1.2 treatment is to neutralize the urine turning ammonic and is let to soak in contact for chemical reaction to take place and is very noticeable with a strong sour odor. This odor diminishes as it slowly evaporates. At this stage, the leather should feel squeaky after returning to its chemistry integrity of pH 3 - 5. Stiff leather is relaxed and sticks together fiber separated by Hydrator-3.3. The penetrated stain removing process continues with hydrating until complete satisfaction during a dry inspection prior to fat and oil replenishing with leather scented Fatliquor LS-5.5. In severe cases color refinishing is the last resort for a pleasing appearance. Note that the mentioned products suffix numbers denotes its pH value in this holistic approach for perforated-leather urine decontamination process. This kit comes with reduced weight option to save on shipping thus all have to be cut and filled up with distilled water prior to use.

    Tips on Urine:
    Urine is a compound waste discharge, comprises of urochrome, uric acid and the ammonium salt to deal with. When deposited urine attracts the natural bacteria from the atmosphere and starts to ferments, a putrid odor will develop from the protein component of the urine and ammonic odor will develop from the ammonium salt. When ammonic odor becomes present, the pH of the contamination would have shifted to 10. Such high pH above the neutral average 3 to 5 of leather causes the amphoteric protein fiber to shift ionic negative (-ve); that causes the protein fibers to repels its other ionic negative (-ve) constituents like the tanning agent, fatliquor and dyestuff. Behaving just like the attraction of a magnet, like poles repel. When the leather constituent breaks hydrogen bond with the protein fiber, the leather starts to denature and revert to rawhide. A typical appearance of an aged or compounded contamination is a darkening effect from the fugitive tanning agents, a whitening effect from the fatliquor. Fugitive dyestuff or bleeding is only apparent from a white towel detection and yellowing from the urochrome. The denaturing or reverting to rawhide effect of the leather is further confirmed by tackiness or in worst-case sliminess in the present of moisture. The leach out fatliquor results in stiffness and fugitive dyestuff results in discoloration. A systematic sequence of decontamination approach includes surface residue removal with CleanUrine-1.5 (pH 1.5), and rinse with Acidifier-2.0 (pH 2.0) recharging the protein fiber ionic positive (+ve) and neutralizing the ammonium salt with KillUrine-2.1 (pH 2.1). Utilizing such a low pH treatment retards bacteria activities from off gassing putrid odors, a natural pH control without the need to use bactericide or fungicide for mold prevention. Therefore, urine is a type of soiling that will require a biochemistry approach to decontaminate it. Restoring the leather begins after decontamination with Hydrator-3.3, a pH 3.3 multifunctional product that has ionic positive (+ve) charging abilities, an active surfactantcy essential for foreign water movement within the inter-fibrillary spaces to redistribute the leather constituents and purging foreign contamination to resurface. This is the last of the wet cleaning process to remove suspended urochrome yellowish compound through visible white tissue paper as an extension of the leather in the wicking process as the leather dries naturally. Only then, without a trace of the urine stain that Fatliquor-5.0 (pH 5.0) replenishing commences. The emulsified fat and oil encased water molecule breaks free when hydrogen bond attraction takes place between the fat and oil with the protein fiber, leaving a breathing space essential for leather transpiration to function naturally. The fat plumps the leather with fullness from easily collapsing into creases and wrinkles during stress or flex, while the oil lubricates the fibers so that they slide over one another like millions of inter-connecting hinges with smoothness. One important unique characteristic of leather is suppleness with strength and much depends on the fatliquor, in this holistic approach to effective leather urine decontamination and restoration. For severe neglected cases with finishes damages as seen in this picture, refinishing commences after leather suppleness restoration.


    Restoration Cleaning:
    1. Dry surface soiling is removed with NubuckBrush-2 and Eraser-4 vacuum off. Remaining soiling is removed with CleanUrine-1.5 (pH 1.5) in conjunction with detailing NubuckBrush-2, Eraser-4 and terry towel extraction until towel shows clean. The remaining residue is further rinse off with Acidifier-2.0 (pH 2.0) and towel extraction until towel shows clean. Leather surface is inspected for any tackiness and should return to a healthier squeaky feel after rinsing.

    Urine Treatment:
    1. Apply KillUrine-2.1 and let it soak until natural dry. Sour odor will dissipate once it evaporates completely.

    1- Hydrator-3.3 is applied to soak into the leather to relax stiff and stick together fibers and to wick out suspended foreign contamination. 2- Wrapping the leather with paper towel and wet it out with Hydrator-3.3 is an advance technique to let the leather soak up the hydrator for slow absorbent leathers. 3- The paper towel is left on the leather to dry naturally; this technique allows the wick soiling particulates to be trapped by the paper towel instead of remaining on the leather surface.

    1- Fatliquor.LS-5.5 is applied and distributed with brushing until the leather is saturated. 2- Continuous second or third application is repeated with each round and let the water content evaporates until saturation. 3- Leave the leather natural drying for extra softness.

    Rub-Resistant Protection:
    1- Protector-S+ is applied by mist spray and brushing to even out appearance. 2- For routine application, a paper towel is recommended to extract soiling simultaneously.

    Roger Koh
    Leather Care System Formulator
    Consultant / Practitioner / Instructor / Coaching
    Last edited by Roger Koh; 09-29-2017 at 10:13 AM.

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