Leather Quality and Properties

Discussion in 'Classic Menswear' started by VegTan, Jul 8, 2013.

  1. DWFII

    DWFII Bespoke Boot and Shoemaker Dubiously Honored

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    I don't think the differences are that significant, especially when you're considering what solvents are being used, etc.. One may have more carnuba, and other product may have more pigment.

    It's only when things like mink oil, mineral oil and silicone start entering the recipes that I get nervous. I used to think that Meltonian was just re-branded Properts (or vice versa.) I don't know, I would gravitate towards more Traditonal and natural products, if I had a choice and knew for sure what the formula was.

    Is it a "marketing ploy"? What isn't?At a certain point...as I've said many times...it isn't about quality anymore (if it ever was), it's about profit.

    To the extent that products fall from grace or start experiencing difficulty with things like colour and oxidation and/or separation in this context, it's almost always because at some level choices were made to substitute relatively expensive raw materials or techniques for cheaper ones.
     
    Last edited: Sep 16, 2013


  2. Munky

    Munky Senior member

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    Thanks, again, DWFII, that's helpful info.
     


  3. VegTan

    VegTan Senior member

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    In 1997, Prof. Tsunoda examined chemical analysis values (water content, total ash content, chromium content, etc.), mechanical properties (thickness, tensile strength, tear strength, etc.), and physical properties (water resistance, water vapor permeability, water absorbency, etc.) of calfskins and steerhides used for shoe uppers.
    http://www.hikaku.metro.tokyo.jp/images/pdf/121pdf/04.pdf
    http://www.hikaku.metro.tokyo.jp/images/pdf/122pdf/03.pdf

    I excerpted water resistance and water vapor permeability from her paper. Water resistance here means the penetration time of water column from the grain side to the flesh side. This paper shows some resin finished leathers (sample nos. 2, 8, 9, 10, 13, 14, 15, 18) will absorb shoe creams well, but corrected grain leathers (sample nos. 16, 17, 19, 20) usually won't absorb them.

    [​IMG]

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    http://www.trespass.co.uk/p/739/technology
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    Here are Norwegian welts/Norwegian stitched soles.

    http://forthediscerningfew.com/2011/12/03/john-lobb-bootmaker-part-iii/
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    http://forthediscerningfew.com/2011/11/26/john-lobb-bootmaker-part-ii/
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    http://news.google.com/newspapers?id=MXYxAAAAIBAJ&sjid=_yEEAAAAIBAJ&pg=2134,2246096
    [​IMG]
     


  4. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

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    The Japanese love doing experiments, don't they?

    What is boxcalf?
     


  5. Munky

    Munky Senior member

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    On balance, I think I prefer the $6 Regal shoes...
     


  6. mezentius

    mezentius Senior member

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    It would be the same mechanism as the one for fatty acids; they're both pretty much the same thing, except fatty acids have a carboxylic acid group at one end which doesn't participate in this reaction anyway. It is done industrially in a chemical plant, but that uses a catalyst instead of sunlight to make the reaction happen a lot faster.

    I wonder if they use optimal ratios of saturated/unsaturated oils in shoe care products. On the one hand, unsaturated oils would make it easier to use as it becomes less viscous, but on the other hand unsaturated oils have more stable radicals and thus have more chance to react in sunlight, forming undesired products.

    (P.S. I'm a chemist and biochemist, so any questions, send them my way)
     


  7. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

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    So if the doctor tells you your triglycerides are high and you eat tons of foods that are basic on the pH scale will you get really soapy blood?
     
    Last edited: Sep 20, 2013


  8. VegTan

    VegTan Senior member

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    I think the American also do experiments.
    http://www.astm.org/Standards/leather-standards.html

    Box calf is a leather tanned only with chromium salts, while some leathers are retanned with vegetable and/or synthetic tanning agents.



    Thank you. Are petroleum distillates dehydrogenated by ultraviolet and/or heat of sunlight?
     
    Last edited: Sep 20, 2013


  9. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

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    What's the advantage of chrome only tanning? Does it look different? Behave differently? My guess based just on reading over the years is that chrome tanning lends to a more malleable leather as opposed to veg tanning. Is the only "benefit" of re-veg-tanning rigidity for certain applications?
     


  10. VegTan

    VegTan Senior member

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    Here is some information.


    For example, chrome tanned leather needs to be retanned to emboss it, because it has less plasticity. Some retanning agents may improve the tensile and tear strength, while I don't have the direct evidence.

    Chrome tanned leather has better breathability and anti-mold property, which would be an advantage.
    http://archive.org/details/jresv44n4p347
    [​IMG]


    The lower leather is Chromexcel which is heavily vegetable retanned. The color of the cross section looks like vegetable tanned leather.
    http://ameblo.jp/emptyg/entry-11081296280.html
    [​IMG]


    Combination tanned leather (Chrome retanned leather) appeared around 1930, AFAIK. Here is the then news.

    http://books.google.com/books?id=gS...cfVkAWv34HACQ&redir_esc=y#v=onepage&q&f=false
    [​IMG]

    http://news.google.com/newspapers?id=KChiAAAAIBAJ&sjid=KXYNAAAAIBAJ&pg=4018,3712748
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    The details are here.
    http://naldc.nal.usda.gov/catalog/CAT86200163
    http://archive.org/details/jresv15n4p363


    Wolverine used to have own tannery and was famous for triple tanned uppers and soles.
    http://www.ebay.com/itm/1950-vintage-ad-for-Wolverine-Shoes-3074-/360736315260
    [​IMG]
     


  11. mezentius

    mezentius Senior member

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    Nope, the base will get neutralised in the stomach before it can reach the bloodstream. In any case, acatalytic base hydrolysis is really slow anyway at body conditions.

    /NOFUNALLOWED

    Depends on which ones. The crucial difference again is the number of double bonds in the molecule, exactly analogous to the rules you posted for biological fatty acids. As a rule of thumb, straight chain petroleum distillates should be more susceptible to dehydrogenation as they increase in size and in the number of double bonds. It's a bit of a bother to search for papers on the topic, though, as the UV seach term brings up mainly characterisation techniques instead of reaction mechanism.
     
    Last edited: Sep 21, 2013


  12. SuitedDx

    SuitedDx Senior member

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    I vacillated between this and the shoe care thread but I thought this might be more pertinent since my question is about leather, specifically the uppers. I recently move to MI where the winters are pretty cold. I was thinking of storing my shoes in the garage but I am hesitant because I do not know how well the uppers will tolerate the winters. Unfortunately, I do not know exactly how cold the winters get here (let alone the temperature in the garage which I assume will be slightly higher) but I think they fall around the teens (F).

    Any thoughts?
     


  13. VegTan

    VegTan Senior member

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    Is Michigan Relative Humidity Map true?
    http://www.usairnet.com/weather/maps/current/michigan/relative-humidity/

    Unless your garage is air-conditioned, high relative humidity is dangerous for leather.


     


  14. green garden

    green garden Senior member

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    So what's the best way to care for leather if you have high humidity and no air-conditioning?
     


  15. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

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    I would say the best thing in that case would be plenty of rest with shoe trees in between wearing so the leather can naturally dry out from sweat. I would condition after it gets worn a few times ~6 wears. Light brushing in between wears.
     


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