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Thread: Vegetable-Tanned (Naked Unfinished) – Fredericia by Borge Mogensen – stained with light discoloration.

  1. #1
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    Default Vegetable-Tanned (Naked Unfinished) – Fredericia by Borge Mogensen – stained with light discoloration.

    We're having leather furniture from Frederica (Borge Mogensen 2202, 2204 and 2209) in our house in Palma de Mallorca but over the years it's getting stained - dark from water/humidity and light discoloration from the sunlight (even there is no direct contact with sunlight as the furniture is in the saloon).
    It's in natural colour (beige/brown) and thinks its vegetable tanned, as it seems to be purely natural without any surface protection.
    Attached please find 3 photographs showing different areas of the furniture with different stains.
    The stains we have are mainly from water or sweat.
    Don't have stains from ink, dye, blood etc.

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  2. #2
    Join Date
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    Here is a general description of vegetable-tanned leathers.

    Vegetable-tanned leather is tanned using tannin and other ingredients found in vegetable matter, such as tree bark prepared in bark mills, and other similar sources. It is supple and brown in color, with the exact shade depending on the mix of chemicals and the color of the skin. It is the only form of leather suitable for use in leather carving or stamping. Vegetable-tanned leather is not stable in water; it tends to discolor, so if left to soak and then dry it will shrink and become less supple, harder and easily crack. In hot water, it will shrink drastically and partly gelatinize, becoming rigid and eventually brittle and crack.

    Unlike other tanning type, vegetable-tanned leathers will require more fatliquor to keep it supple from easily cracking. In extreme dry leather condition with fat and oil moisture level below 7%, it is recommended that leather rejuvenation commence immediately after cleaning or stain removal before the leather becomes dry again.
    Leather without hydrating to relax the leather fibrils and fatliquor replenished prior to drying will leads of stiff leather and subject to easily cracking.

    A leather moisture meter or an equivalent common wood moisture meter will be useful to take the reading of its fatliquor level. A healthy leather fat and oil moisture level would read about 14%.


    Use this Vegetable-Tanned (V) Vachetta – Naked Unfinished, Leather Problem Solving Guide as reference.

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    >>> over the years it's getting stained - dark from water/humidity and light discoloration from the sunlight (even there is no direct contact with sunlight as the furniture is in the saloon). The stains we have are mainly from water or sweat.

    From pictures #3 the leather looks very dry, using a leather moisture meter or a wood moisture meter to take a reading may easily indicate the fatliquor moisture level to be below 7%. If this is so the leather fatliquor (fat and oil) moisture level need to be replenished up to 14% prior to the stain removal. That is to say the leather is only to allow to be dried if there is sufficient fat and oil level in it, otherwise as it dries the internal fiber structure will become stick together tighter, shrunk and when mishandle will leads to cracks.

    The discoloration from sunlight is partly due to the diminishing fatliquor throught evaporation. Leather rejuvenating with Hydrator-3.3 > Fatliquor-5.0 system relaxes the leather structure and can be work back to original dimension prior to top-up its original fat and oil for suppleness.

    In extreme dry leathers it is recommended that the leather structure integrity be put right prior to cleaning and stain removal otherwise upon dry with empty fatliquor may leads to unwanted cracking when mishandled.

    Hydrator-3.3 is used for a variety of purposes and cleaning is also one of its functions, besides reactivating any dormant coloring from beneath the surface - see product description below: Without letting the leather dry below 25% Fatliquor-5.0 is replenished – see product description below:

    Preventing the leather from cracking is the most prime concern when comes to cleaning and stain removing vegetable-tanned leathers. When the leather is structurally healthy cleaning and stain removal commences.


    >>> over the years it's getting stained - dark from water/humidity
    Any browning discoloration is removed with Vachetta-2.8 with a pH value of 2.8, it is applied to the stain area, agitate with the horsehair Brush-1 and towel extract of penetrated soiling until a white terry towel shows clean.
    The entire panel is spray with Vachetta-2.8 to even out appearance and the product is left to natural dry. It works by redox or reduction-oxidation process and any brown coloring improves. The treatment is repeated until satisfaction when dry. It will need to follow with the remaining holistic steps or sequence according to the guide: Vachetta-2.8 > Hydrator-3.3 > Fatliquor-5.0 > Protector-D.

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    Leather Doctor® Hydrator-3.3 is a waterbased pH 3.3 leather-safe hydrator. It is a fatliquor preconditioner with multi functional abilities. Surface application is primary to check for even surface tension free of blotchiness prior to fatliquor replenishing. Structural application will require saturating to an optimum level with moisture oozing out when gently pressed between thumb and fingers.
    The multi functional abilities include:
    a) To check for surface tension for an even appearance free from blotchiness prior to fatliquor replenishing.
    b) To plumps, relaxes and separates crushed, shrunk and stick together fibrils for manipulating away-unwanted creases and wrinkles.
    c) To clean the leather of structural foreign contamination, the plump and limp leather is squeeze with towel laid between the leather and a smooth spatula or equivalent.
    d) To rectify alkaline overexposure areas by facilitating colloidal water movement to redistribute the leather constituents from surrounding areas.
    e) To activate the dormant dyestuff within the leather structure for color refreshing.
    f) To facilitates colloidal water movement within the inter-fibrillary spaces for wicking foreign soiling particulates to resurface.
    g) To stabilize, pH balance and charge the protein fiber below its iso-electric point (pI) ionic positive to hydrogen bond with the ionic negative fatliquor more effectively.
    This universal Hydrator-3.3 is for all leather types including pigmented, aniline, vachetta, nubuck, suede, hair-on-hide and woolskin.

    Instruction:
    A. Surface Tension Inspection:
    A1. Spray Hydrator-3.3 evenly and wipe with lint free towel to free of surface tension for an even appearance prior to fatliquor replenishing.
    B. Stiffness, Creases and Wrinkles:
    B1. Saturate the thickness of the leather to an optimum level with moistures oozing out when gently pressed between thumb and fingers.
    B2. Cover up with plastic wrapping to control evaporation and let it dwell up to 72hrs for softness.
    B3. Manipulate by stretching and cross flexing to relax the leather to satisfaction prior to fatliquor replenishing.
    B4. With satisfaction the Fatliquor-5.0 has to be immediately replenished while the leather is perhaps at 25% Hydrator-3.3 moisture level.
    C. Cleaning:
    C1). A combination of cleaning while saturating the leather is done with horsehair Brush-1 on the surface and towel extracting it. Deep cleaning beneath the surface from the leather structure for liquid stain is done with squeezing the leather with a smooth spatula with a towel in between to reduce abrasion and absorbing the foreign contamination – See F below
    D. Rectify Alkaline Overexposure:
    D1. Saturate the thickness of the leather to an optimum level with moistures oozing out when gently pressed between thumb and fingers.
    D2. Cover up with plastic wrapping to control evaporation and let it dwell for redistributing of the leather constituents from surrounding area.
    D3. Observe for appearance and test by finger for tactile squeaky feel prior to fatliquor replenishing.
    E. Activating Dormant Dyestuff to Resurface:
    E1. Saturate the thickness of the leather to an optimum level with moistures oozing out when gently pressed between thumb and fingers.
    E2. Cover up with plastic wrapping to control evaporation and let it dwell up to 72 hours for excess dyestuff to resurface.
    E3. Remove plastic cover and let it natural dry to observe color improvement prior to fatliquor replenishing.
    F. Removing Penetrated Stains:
    F1. Saturate the thickness of the leather to an optimum level with moistures oozing out when gently pressed between thumb and fingers.
    F2. Cover up with plastic wrapping to control evaporation and let it dwell up to 72 hours for foreign soiling particulates to resurface.
    F3. Remove plastic wrapping, replace with tissue paper without airspace to trap stains as it dries instead of remaining on the surface. Recommend that Fatliquor-5.0 is replenished in combination at this stage especially if the leather has already show signs of cracking.
    F4. Peel tissue paper when crispy dry and erase with Eraser-4 or Eraser-5 for suede accordingly prior to fatliquor replenishing.

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    Leather Doctor® Fatliquor-5.0, a micro emulsion of fat, oil and water is an anionic charged pH 5.0 fatliquor for rejuvenating all leather types. It relaxes coarse breaks, creases and wrinkles enhance suppleness and prevent cracking. It softens the leather with stretchability, compressibility and flexibility, while enhancing its rip tensile strength greatly. It is for replenishing the original fat and oil that diminishes thru sun-bleaching, ageing, heat and alkaline overexposure or cleaning. On application, the water-encased molecule breaks free when hydrogen bond attraction takes place between the fat and oil with the protein fiber. The excess free water content wicks out leaving a breathing space behind for leather natural transpiration. 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 smoothly like millions of inter-connecting hinges. Thus helps to keep leather at its optimum physical performance and prevent premature ageing. This universal Fatliquor-5.0 is for all leather types including pigmented, aniline, vachetta, nubuck, suede, hair-on-hide and woolskin.
    Leather Approximate Quantity or Percentage of Fatliquor:
    The quantities of fatliquor (fat and oil) contents retained in the leather after an universal tannery fatliquoring process may varies up to 14% depending on the leather types and it usage. This percentage drops as the fat and oil content diminishes or leaches through ageing, water, heat or chemical overexposure.
    Leather rejuvenating or fatliquor replenishing is base on weight of the leather in relation to the percentage of remaining fatliquor. A simple calculation of percentage of fatliquor topping up requirement would be as follows:
    If the weight of the leather in question is 100gm and fatliquor (fat and oil) content meter reading is less than 1%.
    By applying 80gm of Fatliquor-5.0 to it will deliver an end result incremental of 13.3% fatliquor when dry as the 66.6% water contents evaporates.
    In the leather rejuvenating Hydrator-3.3 > Fatliquor-5.0 > Hydrator-3.3 system, Hydrator-3.3 plays an important role by relaxing, opening up the inter-fibrillary spaces, facilitating and redistributing colloidal water movement, protonating and doing all the pre-conditioning work prior to fatliquoring including cleaning up any excess surface remnants to have a sticky-free surface. In practice the ratio for Hydrator-3.3 is 2 to 1 of Fatliquor-5.0.
    It works out to be approximately 160gm of Hydrator-3.3 plus 80gm of Fatliquor-5.0 to replenish a 100gm dry leather from less than 1% back to the original tannery up to 14% fatliquor content.
    Instruction:
    1 Apply Fatliquor-5.0 and redistribute with foam brush until saturation.
    2 Repeat applications each time water contents evaporate until fully saturated.
    3 Drive remaining surface remnants free of milky fat and oil until it turns clear with Hydrator-3.3.
    4 Allow natural drying for extra softness.
    5 Suppleness for vegetable-tanned leathers is further stake or massage or flex accordingly with a little wet back with Hydrator-3.3 prior to doing so to prevent cracking from under replenished leather.
    Tips:
    1 When crispy dry, prior surface contaminations/damages may darkens as soiling particulates resurface.
    2 Removes soiling particulates with Eraser-4 for all leathers including nubuck and Eraser-5 for suede.
    3 Stretching the darken areas lightly will also lightens the appearance.

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    Vachetta-2.8 is a specialty leather browning treatment design especially for unfinished veg-tan leathers popularly known for handbag as Vachetta. This is a waterbased pH 2.8 product, which is particularly effective in emulsifying oily soiling, lightening suntan, tarnish and liquid browning staining effect. Use in conjunction thereafter with Hydrator-3.3 to relax, Fatliquor-5.0 to soften thus prevents cracking and Protector-D to seal, conceal and allow leather transpiration in a holistic care system. When vachetta leather color turns to dark in extreme cases especially to constant body contact areas like handles, it will require Degreaser-2.2 follows with Acidifier-2.0 found in Kit V4 to decontaminate the oil, grease and sweat as the first phase prior to browning treatment, leather rejuvenation and protection.
    Instruction:

    Browning Stain Removal:
    1. Remove dry soil prior to product application.
    2. Shake well, spray and saturate with horsehair brushing for an even appearance and towel extract until it shows clean.
    3. Option is to use a saturate cotton swab and clean until the cotton swab shows clean or use a terry towel.
    4. Let natural drying and inspect result, repeat as necessary.

    Hydrate Stiff Leathers:
    1. Saturate with Hydrator-3.3 to soften and for an even appearance.

    Soften Leather:
    1. Saturate with Fatliquor-5.0 and as water contents evaporate, repeat application.

    Protect Leather:
    1. Apply Protector-D for an even appearance.


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    Leather Doctor® Kit V6 is a combination problem solving kit that includes products from Kit V5.dr, Kit V5.ds and Kit V3. Common stains encounter in the course of vachetta leathers lifetime includes the darkening effect from neglected body oil, grease and sweat contact, the occasion ink and dye transfer, and the browning from liquid and sun tanning seasoning effect just like our skin. The protein leather fiber is an ionic positive (+ve) “amphoteric” material thus pH sensitive to influence by alkaline solution shifting ionic negative (-ve), even water with a pH of 7 often discolors or browns it. Its other non-amphoteric leather constituents like the tanning agent and the fatliquor remains ionic negative (-ve), hence just like a magnet – “like poles repel”, breaking of the hydrogen bond between them, the leather denatures and in extreme cases revert to rawhide. This adverse contamination is rectify by Degreaser-2.2 > Acidifier-2.0 system, both to simultaneously degrease and protonate the protein fiber ionic positive (+ve) to its pH chemistry integrity. Ballpoint, printing ink, dye transfer, gum, sticky substance and accumulated soiling will require the penetrating, lubricating and suspending power of Prep-4.4 follows with Clean-3.8 to remove the sticky residue and Rinse-3.0 to a healthy squeaky feel. Browning from liquid stain or sun tanning is eliminated or reduced by chemical reaction from Vachetta-2.8 when dry. The above describe the three common class of stain removal. Leather rejuvenating mandatory sequence follows to soften and strength the leather from stiffness that may leads to cracking when flexed. Among leather finishes type, vachetta leathers is the most fatliquor (fat, oil and water) thirsty and will require more fatliquor to soften it then chrome-tanned leathers. In order to lubricate each fibril within the leather structure behaving like millions of interconnecting hinges the fat and oil has to be hydrogen bonded to the fibrils. This is accomplished by preconditioning the leather structure with Hydrator-3.3 effectively prior to faliquor replenishing it with Fatliquor-5.0 in between drying cycle until fully saturated. Natural slow drying in between application produces a softer leather. Protecting the leather with Protector-D 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.



    Roger Koh
    Leather Care Consultant / Practitioner / Instructor / Coach
    Last edited by Roger Koh; 07-03-2015 at 11:42 AM.

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