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Thread: Vegetable-Tanned (Aniline) - Vintage Chair restoration

  1. #1
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    Default Vegetable-Tanned (Aniline) - Vintage Chair restoration

    Hi,

    I have these chairs that I would like to clean up and conserve rather than refurbish but I think replacing the the piping on the arms is unavoidable and I will have to color match it. It's difficult to know what the original colour was like and I won't know until I get the underside covering off. Any suggestions as to how to tackle this without ruining its charm?

    Thanks,
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  2. #2
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    This leather is positive identified as unfinished Veg-Tan a.k.a Vachetta 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, and harder. In hot water, it will shrink drastically and partly gelatinize, becoming rigid and eventually brittle.


    >>> It's difficult to know what the original colour was like and I won't know until I get the underside covering off.

    You may be surprise the original color may be close to the color of the wooden legs (a reason to have the whole chair looks more harmonious in term of color).


    >>> I think replacing the piping on the arms is unavoidable and I will have to color match it.

    You will be making a mistake to color match it – the colors comes from the tanning agent itself and not from any dyestuff, instead remove all the contamination that darkens it especially degreasing the armrest and lightning up the sun-tanning color effect. I would leave the piping as it is without repairing it, otherwise it will not match up with the other surface cracking, thus spoil the aesthetic look.


    >>> I have these chairs that I would like to clean

    Cleaning will include degreasing and pH neutralizing existing foreign pH contamination with Degreaser-2.2 > Acidifier-2.0.
    May need Vachetta-2.8 to further reduce the sun tannin effect (lightens up the leather back to the original color).


    >>> and conserve rather than refurbish.

    Conservation in this contact may mean restoring the chemistry integrity of the leather back to its original pH value close to 3 for veg-tanned leather rather than 4 for most chrome-tanned leathers. All the cracking shows that the leather is over dried of its moisture contents. Moisture contents that prevents the leather from cracking was original applied during the fatliquoring process and the tannery standard averages 12% while gloves soft leather may go higher in percentage. During the cleaning and drying process the leather will shrink further and need lots of hydrating to separates the now shrink and stick together fiber prior to fatliquor replenish it. This leather type (veg-tanned or vachetta) is very thirsty of fatliquor. It is starving of fatliquor that manifested as cracks.


    >>> Any suggestions as to how to tackle this without ruining its charm?


    There are positive charms and negative charms, know how to distinguish between the two.
    The negatives are the foreign contamination that do affect the chemistry integrity of the leather structure and have to go (using Degreaser-2.2 > Acidifier-2.0).
    The lightening of the sun tannin is of a personal taste, so it is neutral (otherwise use Vachetta-2.8).
    Cracks is to be left alone – only softening and strengthening the leather structure according with (Hydrator-3.3 > Fatliquor-5.0).
    Piping damages is charming in its own right with history of usage that matches the natural cracks of the leather.

    Beauty as aesthetic is in the eyes of the beholder but know the difference when contamination is concern or the leather is deprive of its chemistry balances.


    Roger Koh
    Leather Care Consultant
    www.LeatherDoctor.com


    Here's the problem solving guide:

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    Products information:

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    Leather Doctor Kit V5.dr – Vachetta Leather Degreaser Kit
    Leather Doctor® Kit V5.dr, vachetta, saddlery and veg-tan leather degreaser kit is an innovative leather-safe degreasing system for removing grease and sweat contamination. When sweat accumulates and ages it shift alkaline, besides the apparent darkening effect it will also impart a sticky feel to the leather. Leather is composed of protein fiber with other leather constituents like the tanning agents and the fatliquor. The tanning agent preserves the leather while the fatliquor softens it. The protein fiber is amphoteric while the other component is non-amphoteric. They come together by hydrogen bonding. When the pH of the leather rises due to the sweat, the protein fiber begins to shift ionic negative and breaks bond with the ionic negative tanning agent and the fatliquor. The protein fiber loosing the ionic attraction from the tannin agent denatures and revert the leather to rawhide as experience with tackiness or stickiness in extreme cases. The stiffness of the leather is due to the loss of the fatliquor that lubricates the fibers thus the fiber becomes stick together and when flex cracks. The darkening effect is partially contributes by high pH exposure, as alkaline darkens and acidity lightens the appearance of leather. To rectify the compound problem the grease and sweat contamination is remove. The protein fiber is degreased and recharged ionic positive below its iso-electric point (pI) by using Degreaser-2.2 follows by Acidifier-2.0. This combination degreasing and rinsing process should improve the darkening effect while reversing the leather to a healthy squeaky feel. Hydrator-3.3 helps rectify alkaline overexposure areas by facilitating colloidal water movement to redistribute the leather constituents from surrounding areas, while purging foreign contamination to resurface and charging the protein fiber below its iso-electric point (pI) ionic positive to hydrogen bond with the ionic negative fatliquor more effectively. Fat and oil is replenished with Fatliquor-5.0 to return the leather for softness and suppleness when dry. Protector-D heals and conceals scuff and abrasion marks; imparts a rub resistant draggy-feel against friction rubs and shield against sticky soiling while prolonging the appearance of the leather longer. Note that the mentioned products suffix numbers denotes its pH value for a safer degreasing approach to pH sensitive leather. Leather is an amphoteric material and shifting of it pH value obliviously causes the leather to darkens, denature and reverts to rawhide. More details:
    http://www.leatherdoctor.com/servlet...t-V5.dr/Detail


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    Leather Doctor Kit V3 – Vachetta Leather Browning Removal Kit
    Leather Doctor® Kit V3, unfinished leather care system is design for corrective appearance of vachetta, saddlery and veg-tan leathers from browning liquid stains. These alkaline pH sensitive leathers when neglected often suffer unsightly browning stain marks from a variety of liquid sources. Even apparent clean rain and tap water often leave a lightening spot with an outer ring. The pH 7 alone of water will often cause a rippling effect on the tannin that destabilize and causes it to moves. Browning correction is perform by using Vachetta-2.8, a pH 2.8 specialty leather cleaner that is particularly effective in emulsifying oily soiling, lightening suntan and water staining effect. A holistic system includes rejuvenating the leather structure for softness with Hydrator-3.3 to relax, follows with Fatliquor-5.0 to soften when dry and protecting with the healing properties of Protector-D thereafter. The lightening effect takes place when the leather dries. When leather is wet and dry again, it will often stiff up, as the fibers becomes stick closer together. Hydrator-3.3 helps separate and open up the inter-fibrillary spaces preconditioning for effective Fatliquor-5.0 replenishing to lubricate for leather flexing smoothness from cracking. Replenishing the leather structure with fat and oil after browning corrective cleaning besides the softening effect also prevents the ingress of liquid stains as a preventive measure. When leather is full of fat and oil, it makes the leather less absorbent. Fat and oil conditioning or rejuvenating with Fatliquor-5.0 mellows and enrich the appearance of the leather while most oil conditioners will simply darkens and dulls the appearance poorly. Protector-D enhances a rub resistant draggy-feel against friction rubs and is use routinely to conceal and fill scuffmarks. Body contact areas should be clean routinely with Clean-3.8 follows with Rinse-3.0, thereafter applied with non-stick protection and commence for another cycle of use. Darken and prolong body grease and sweat contacts will require a degreasing process with Degreaser-2.2 follows with Acidifier-2.0 in most cases. Preventive cleaning and protection to shield against sticky soiling, with the abilities to heal and conceal lightening scuff and abrasion marks keeps the leather appearance level high at all times rather than relying on corrective or salvage cleaning where the cleaning appearance deteriorates and diminishes with each cycle. Note that the mentioned products suffix numbers denotes its pH value in this holistic approach to removing vegetable, plant and water stains from vachetta, saddlery and veg-tan leathers. More details: http://www.leatherdoctor.com/servlet...-Kit-V3/Detail
    Last edited by Roger Koh; 11-04-2013 at 02:59 PM.

  3. #3
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    Thanks Roger... I'm in awe of your knowledge!

    I have had a chance to take a closer look at them now and have a concern about one of the back panels, it seems to have a different finish that wrinkles when pressed and the color is slightly darker than the others, which stay smooth. It could have been replaced?

    The original color has confused me because the sides and seams indicate a lighter color as you said, but not as light as the legs (as in the photo attached) but down the side of the seat cushions are much darker (I'll send a photo when I have better light...it's the middle of the night here). Could this just be down to the way they have been looked after?

    I have found a clue to there possible origin and use. They were very dusty and I dusted them over and got a paint brush to clean down the side of the seat cushions and found an Italian biscuit wrapper...the kind you get with coffee in Italian cafés. It kind of fits there style, although I thought they might be French. Still not sure on there age, possibly 1950 or 60 but could be older.

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  4. #4
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    I've come to the conclusion that the darker color down the side of the seat cushions is a combination of dirt and grime and being wiped down regularly with with a damp cloth over time. If it wasn't for the light fading the exposed panels on the front of the chairs they would probably be be a similar color.

  5. #5
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    [QUOTE=Cherry;14129]Thanks Roger... I'm in awe of your knowledge!

    I have had a chance to take a closer look at them now and have a concern about one of the back panels, it seems to have a different finish that wrinkles when pressed and the color is slightly darker than the others, which stay smooth. It could have been replaced?

    The original color has confused me because the sides and seams indicate a lighter color as you said, but not as light as the legs (as in the photo attached) but down the side of the seat cushions are much darker (I'll send a photo when I have better light...it's the middle of the night here). Could this just be down to the way they have been looked after?

    I have found a clue to there possible origin and use. They were very dusty and I dusted them over and got a paint brush to clean down the side of the seat cushions and found an Italian biscuit wrapper...the kind you get with coffee in Italian cafés. It kind of fits there style, although I thought they might be French. Still not sure on there age, possibly 1950 or 60 but could be older.



    >>> I have had a chance to take a closer look at them now and have a concern about one of the back panels, it seems to have a different finish that wrinkles when pressed and the color is slightly darker than the others, which stay smooth. It could have been replaced?


    Please show pictures from different angle and distance, if I can detect the difference.

    If the panel was been replaced, perhaps the different in thickness may play a part that shows the tension difference.

    Vachetta-2.8 testing when dry will be able to confirm if this panel is of the same leather type.

    Another leather type identification is to look at the reverse side at the stapling edges; otherwise the stitching holes will be able to tell as well (show some to these close-up pictures and I will help).


    >>> The original color has confused me because the sides and seams indicate a lighter color as you said, but not as light as the legs (as in the photo attached) but down the side of the seat cushions are much darker (I'll send a photo when I have better light...it's the middle of the night here). Could this just be down to the way they have been looked after?

    The darkening of this veg-tan leather are mainly caused by UV lights and alkaline cleaning solution, even tap water at pH 7 will marks and browns the leather.


    >>> I have found a clue to there possible origin and use. They were very dusty and I dusted them over and got a paint brush to clean down the side of the seat cushions and found an Italian biscuit wrapper...the kind you get with coffee in Italian cafés. It kind of fits there style, although I thought they might be French. Still not sure on there age, possibly 1950 or 60 but could be older.

    Your research to the origin may bring value to these chair, I believe it is only about 65 years that it is considered an “antique” piece worthy of collection. To bring more value to the chair it is wise to conserves and restore these chair without erasing the age. Let the cracks and wear shows their age. Only removes the contamination and rejuvenate the leather structure with pH balancing or protonate the protein fiber or charge the leather structure more ionic positive (+ve) for the leather chemistry integrity and lastly soften and strength the leather by fatliquor replenishing to prevent further cracking. You may do a test with tap water if the leather feels sticky or slimy on the contaminated armrest. If so the leather is denaturing or reverting to rawhide and definitely need to pH balance back to its neutral pH with to a squeaky feel.

  6. #6
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    Quote Originally Posted by Cherry View Post
    I've come to the conclusion that the darker color down the side of the seat cushions is a combination of dirt and grime and being wiped down regularly with with a damp cloth over time. If it wasn't for the light fading the exposed panels on the front of the chairs they would probably be be a similar color.


    Unfinished Veg-Tan leathers do not fade under UV or sun light, it is the only leather type that behaves just like our skin – only darkens or tans or becomes browner.


    Roger Koh
    Leather Care Consultant
    www.LeatherDoctor.com

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