1. And... we're back. You'll notice that all of your images are back as well, as are our beloved emoticons, including the infamous :foo: We have also worked with our server folks and developers to fix the issues that were slowing down the site.

    There is still work to be done - the images in existing sigs are not yet linked, for example, and we are working on a way to get the images to load faster - which will improve the performance of the site, especially on the pages with a ton of images, and we will continue to work diligently on that and keep you updated.

    Cheers,

    Fok on behalf of the entire Styleforum team
    Dismiss Notice

Leather Quality and Properties

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

  1. glenjay

    glenjay Senior member

    Messages:
    748
    Joined:
    Feb 13, 2009
    Location:
    Bend, Oregon
    



    The most recent Safety Data Sheet I have read on Nikwax waterproofing wax for leather is about 9 years old (http://www.osabrands.com/images/products_pdf/Nikwax_Nikwax Waterproofing Wax.pdf), so it is possible they could have changed their formula since.

    It is also important to note that thicker leather like that in hiking and mountaineering boots can take more abuse that thinner leather.

    In regard to suffocating leather: So as not to trap perspiration within the leather itself the leather needs to allow some level of moisture to pass through.. Most people underestimate how much their feet sweat. If you want to see how much an unventilated foot sweats just place your bare foot in a plastic baggie and wear it around in your shoe or boot for a day.

    Both wax and oil allow for passing a certain percentage of moisture the denser the oil or wax the more impedance to moisture there is. Trapping moisture in leather allows it to more easily oxidize the oils and break down the protein bonds of the leather. This is basically the definition of dry rot in leather. However this does take a while to happen, and even longer in thicker leather.

    In regard to petroleum distillates: The basis for all petroleum distillates is the molecular hydrocarbon chain. As the ratio of hydrogen to carbon decreases, and the chain becomes shorter, the molecule becomes more volatile (like a gasoline). Hydrogen atoms can be removed from a hydrocarbon through exposure to UV radiation, as well as other chemically induced means.

    In regard to silicone: There are certainly a vast array of silicone compounds, but they all have one thing in common - they contain silicon which is less reactive than its chemical analog carbon. Because of this most silicone compounds are typically heat-resistant, water-resistant and rubber-like. This also means that unlike oil, silicone is much more difficult to flush out of leather, and is also much more likely to smother leather.

    There is no requirement of a Materials Safety Data Sheet (MSDS) to list all ingredients, or the ration of ingredients, in a compound; Only those chemicals deemed as hazardous need be listed (as shown in the MSDS for Nikwax in the link above). So, finding the specific silicone compound composition in a given shoe care product would be quite difficult.

    I should point out that I am not a chemist by profession, so I am sure there are others here that could give a better explanation in regard to these aspects. I seem to remember that a member that posted in this thread was an actual chemist, and certainly a better source to answer these types of questions.
     
    1 person likes this.
  2. dbhdnhdbh

    dbhdnhdbh Senior member

    Messages:
    330
    Joined:
    Sep 3, 2012
    I have found some data on water vapor permeability through leather treated with silicone compounds. However, it seems that

    1. The effect is very complicated, depending on the exact silicone formulation used, how it is applied, how the leather was tanned and fat liquored, whether the silicone was applied during leather manufacture or afterward and how the silicone substance is treated after application.

    2. Reports of water vapor permeability effects suggest that it is minor with those silicones tested. One mentions a 20% reduction in permeability. Of course, see #1 above, this figures is meaningful only for that particular treatment on that particular leather.

    There are also reports that waxes and oils also reduce vapor permeability. I have a pair of hiking boots whose manufacturer explicitly said to avoid waxes and oils, and use only fluorocarbon spray to maintain water repellent properties.

    I suspect that wax and oil effects on permeability is a less interesting current question. The most recent paper I can find on this phenomenon was published in 1950.

    So far I have not found anything on detrimental effects of silicone on leather other than incompatibility with other treatments. It seems that once the leather it treated with silicone, SOME other treatments will not remain in the leather. From experience, I have treated boots with silicone and then with SnoSeal and they appear to take the beewax as well as boots not treated with silicone. But I did not do any chemistry on them.

    It is also surprising that I cannot find anything directly addressing the extent to which perspiration leaves the shoe through the lining and then through the outer leather, or by evaporation from the lining surface once the shoes are removed. There is plenty indicating that the lining absorbs water, but the rate of water loss through the upper vs from the lining seems to tilt toward very little getting out through the upper. [perhaps one gram through a single layer of leather during 12 hour day of shoe wear. If that gets the water to the surface of the lining between the lining and the upper, presumably some small fraction of that would make it all the way through the vamp.] Unfortunately, this comes from extrapolations from permeabilities reported for some leather samples and unclear how well it relates to real life shoes. It also does not address the effects of conditioners, polish and waxes on the vapor permeability of the upper.

    For the moment, I am skeptical that any significant amount of water migrates all the way through the lining, through the upper and evaporates from the upper surface during a day's wear. I may try the plastic bag over the shoe trick to see how much accumulates from such evaporation. Rather that put it over the entire shoe, where evaporation around the ankle could confound the results, I think I will place it over the vamp and see whether any dampness appears.

    I suppose I wonder where the idea that "Silicone damages leather" came from. It might be true, and it is certainly repeated frequently on the internet, but finding hard evidence in support of this idea is proving surprisingly difficult.



    re: Nikwax formulation

    Quote:
     
    Last edited: Dec 29, 2013
  3. DWFII

    DWFII Bespoke Boot and Shoemaker Dubiously Honored

    Messages:
    8,241
    Joined:
    Jan 8, 2008
    Location:
    The Highlands of Central Oregon
    

    If you get a shoe or boot soaking wet, how does it dry out? I have lasted boots and shoes that were thoroughly soaked-- lining, heel stiffener and vamp/quarters. Since they are pulled tight to the last and the last is often plastic, how do they dry out? And in only a day or two?

    All waterproofing applications be they wax, be they oils, be they mineral oils, silicone, whatever, prevent the transpiration of moisture. If they are applied to keep water out, how can they help but keep water in? And your boots/shoes will always be hotter when treated to repel water.

    Now...no disrespect intended but if you are satisfied with the results of your investigations into the "detrimental effects of silicone," why pursue it any further? We both know that in all probability, nothing anyone here can say will convince you. I'm no chemist, Glen's no chemist (although he's a heck of a lot closer than I am).

    What is being offered by Glen and others is advice based on real world, hands-on experience across many different situations. Situations that no single individual consumer of shoes is likely to duplicate in a lifetime.

    You can find studies on the internet...probably funded by folks with a vested interest...that say silicone is harmless. I have no vested interest either way. Maybe the case could be made that Glen does, but my sense from reading his posts over the years is that he is an honest broker of information.

    My experience over many decades and using silicone in lots of different ways and seeing the long term results makes me very cautious about recommending it. I think silicone is strange stuff. I don't think that one application will destroy the leather or detrimentally affect your boots or shoes. But prolonged use on dress shoes in particular will make shining difficult and so load the fibers of the leather with oil (and this is true of any oil but natural oils in particular tend to congeal or oxidize) that you might as well be wearing greasy plastic.
     
    Last edited: Dec 29, 2013
    1 person likes this.
  4. dbhdnhdbh

    dbhdnhdbh Senior member

    Messages:
    330
    Joined:
    Sep 3, 2012
    Quote: A day or two is a lot longer than the 8-12 hours that someone would wear a pair of shoes. The rate of drying is proportional, among other things, to the water content at the start. I can easily believe that the water content would drop rapidly in the first few hours, and more slowly as time goes by. Under the circumstance you describe, I agree that the water in the lining would have to evaporate through the upper. But it does not sound like it happens in 12 hours.

    Quote: Well, the scientific literature says these treatments work in a manner similar to Goretex. They do not permit liquid water to pass, but they do let the vapor get through. The mechanisms by which they work have been studied for decades. It seems that some of the water motion is through air spaces, some is by tracking along the wet surface of the collagen fibrils. This was discussed in some detail in the old paper

    "Factors Affecting the Water Permeability of Leather". 1950, Journal of Research of the National Bureau of Standards, 44(4):347.

    In fact, there are studies of waterproofing treatments that worked poorly, producing leather that absorbed a lot of water, while not permitting water to pass. See, for example "Comparable Evaluation of Leather Waterproofing Behaviour upon Hide Quality. I. Influence of Retanning and Fatliqouring Agents on Leather Structure and Properties" MATERIALS SCIENCE-MEDZIAGOTYRA Volume: 18 Issue: 2 Pages: 150-157

    There are plenty of articles discussing methods of making the various silicone treatments, but none that I have found so far have assessed the longer term effects of these waterproofing approaches on leather durability.

    Quote: That is just it. I am not satisfied. Many people seem convinced that silicones used for waterproofing damage leather, but so far no one can present any data supporting that, or an explanation of how it works. As I indicated, I have not found any scientific publications that address these issues. Technical papers from manufacturers describe how some silicone treatments work, but they do not discuss whether they could damage leather. The papers published in the scientific literature were funded by national government science foundations, not by chemical companies. So I don't feel that I am anywhere close to an answer as to whether silicones damage leather, if so which ones do this, or how they do it.

    Quote: I am not so much seeking to be convinced as to be pointed toward some scientific evidence. I don't need someone to tell me "the answer", I am just hoping someone knows of studies that had attempted to answer these questions, and where they were published.

    Quote: That is certainly valuable, but I am looking for the underlying science. Particularly with respect to silicone, that covers such a range of substances that it would seem hard to generalize the effects.

    Why do I bother to ask?

    Mainly curiosity, but I suppose the answers could have some influence on choice of waterproofing compounds to use on my leather.
     
  5. emptym

    emptym Senior member Moderator

    Messages:
    7,321
    Joined:
    Sep 22, 2007
    Fwiw, I don't think Nikwax uses silicone. On their website they say they use a compound that includes modified forms of EVA (ethylene-vinyl acetate) and mineral wax. I've used their products for years on Gore-tex jackets and pants, but haven't tried their boot stuff. For waterproofing boots, I used mink oil for decades and switched to Sno Seal about five years ago based on Crane's recommendation here.
     
    Last edited: Dec 29, 2013
  6. Fang66

    Fang66 Senior member

    Messages:
    10,701
    Joined:
    Apr 29, 2009
    Location:
    Nihon
    

    Liquid water and water vapour are two different animals.
     
  7. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

    Messages:
    33,334
    Joined:
    Oct 16, 2006
    Location:
    New York City
    There was that weird experiment posted on here, or the shoe care thread with that Asian guy that polished one of his shoes with an insane amount of kiwi and the other with just a little bit and ran on a treadmill or something for a while. Then his feet were put in these glass boxes that measured humidity and the shoe with more wax on it was emitting less water vapor because it was encased in so much wax.

    I don't think anybody is saying silicone is inherently bad for leather. It is in like 99% of cosmetics and is inert. I believe many women are known to have it placed in their breast cavities. I think the issue arises with repeated use over time; the build-up that occurs and the effects of the build-up on both leather health and appearance. The effect over time isn't endemic to silicone, but anything that is repeatedly applied to leather over time. I think the issue that is endemic to silicone is the fact that they aren't nearly as soluble as many other shoe products, especially natural ones so when they are applied they are there to stay unless some sort of harsh method is used that will inherently damage the leather like a detergent, mineral spirit, or acetone.

    I am a bit of a fuddy-duddy when it comes to cosmetics and such and one thing that I have learned over time is the fact that sulfates are used has foaming agents for cleaning. Essentially detergents in probably 98% of hair, hand, body washes (and even a lot of conditioners). This is an artificial soap, a detergent, made by the German's during WWII (supposedly according to my high school Physics teacher) when natural castile soap had run out and became hard to get a hold of. Th point I am making is that all of the silicones in hair and skin products that makes us feel smooth is washed away from these harsh detergents using sulfates. If you look online at the nerdy hair and skin community forums (think Style Forum for hair and skin stuff) they say if you are switching to natural soap you should switch to natural conditioners and lotions and such because the natural soap won't ash away all of the silicones in the other products and it will clog your pores, make you feel kind of matte and waxy and make your break out. Essentially, it will keep building up. Logically thinking about it the effect of silicones on leather would be very much the same. Do you see this happening in the wild? If not, awesome keep using them, but if you can avoid using them at the very least for peace of mind you don't have to change your behavior in the slightest, just change the product. Personally I am all about peace of mind without any change in behavior, seems like a win-win to me.
     
    Last edited: Dec 30, 2013
    4 people like this.
  8. DWFII

    DWFII Bespoke Boot and Shoemaker Dubiously Honored

    Messages:
    8,241
    Joined:
    Jan 8, 2008
    Location:
    The Highlands of Central Oregon
    

    Surely not as extreme as all that. Are they not both H2O? One matter in two different states, perhaps.

    It may be worth noting that when water is used or required for lasting shoes or boots it can be applied by immersion, spritzing or in steam cabinets (the preferred commercial approach). Same results, no harm no foul.

    Perhaps of interest also...and more to the original point...is that when a wet boot is lasted some small amount of moisture is expressed (squeezed out) but the most of it remains. And the only way it dissipates is by evaporation--the self-same mechanism that allows moisture from the foot to transpire through the leather to the outside.

    Now I'm no chemist or scientist...just a simple country shoemaker who has seen this process many times...so take it for what it's worth.

    :cool:
     
    Last edited: Dec 30, 2013
  9. RogerP

    RogerP Senior member

    Messages:
    8,333
    Joined:
    Nov 1, 2012
    Location:
    Oakville, Ontario, CANADA
    Liquid water and ice are both H2O. Same molecule in two different states. Just sayin'.
     
  10. Fang66

    Fang66 Senior member

    Messages:
    10,701
    Joined:
    Apr 29, 2009
    Location:
    Nihon

    liquids and gases behave differently when faced with a semi-permeable membrane.
     
  11. DWFII

    DWFII Bespoke Boot and Shoemaker Dubiously Honored

    Messages:
    8,241
    Joined:
    Jan 8, 2008
    Location:
    The Highlands of Central Oregon
    

    I'm sure that's true. And again I am not chemist so anyone who is feel free to correct me.

    That said, aside from the effects of heat and/or gravity, water in both liquid and vapour states share one commonality--they both tend to abhor areas that have lesser concentrations of moisture. IOW, both water and vapour will move to spaces that are dry or drier. Liquid water...even ice...will evaporate, no heat needed--it is water trying to take over the world.

    Whether that's good science or not, it is both observable and demonstrable....and practically speaking the only consideration that bears on the discussion of silicones, oils, waxes and waterproofing leather.
     
    Last edited: Dec 30, 2013
  12. Fang66

    Fang66 Senior member

    Messages:
    10,701
    Joined:
    Apr 29, 2009
    Location:
    Nihon

    "both water and vapour will move to spaces that are dry or drier"
    This is true, but their ability to do so, and the rate that they do do so will vary. Even so water vapour inside a shoe will tend to condense anyway so in this context the point is mostly moot. Also for most footwear getting moisture out of the shoe is a bigger issue than stopping it getting in, I don't waterproof any of my shoes or boots, except a pair of tactical boots that I use for hiking. Then again I stay indoors when the weather is foul.

    But regarding your original question, "If they are applied to keep water out, how can they help but keep water in?", many waterproofing compounds tend to mostly act by forcing water to bead up and thus roll off the surface, if you break the surface tension of the beads and allow them to sit on the surface the water will soak in, this beading action does not occur when the water transfers from the non-coated side. The water will transfer from the more moist inside to the less moist outside and then evaporate as water vapour (wicking). These waterproofing treatments will interfere with this process to a certain, but generally not significant, degree.
     
  13. DWFII

    DWFII Bespoke Boot and Shoemaker Dubiously Honored

    Messages:
    8,241
    Joined:
    Jan 8, 2008
    Location:
    The Highlands of Central Oregon
    

    I understand your explanation. I'm not sure I agree with it...or better way to say it--that's not consistent with my experiences.

    I use conditioners such as Lexol and Bick4 to inhibit drying during crimping and lasting. Because if drying happens too fast, water staining can occur.

    Neither of those products contain much in the way of oils, yet they still inhibit evaporation from the inside to the out.

    Well... practical experience aside I'm getting out of my depth so...I'll leave it at that.
     
  14. RogerP

    RogerP Senior member

    Messages:
    8,333
    Joined:
    Nov 1, 2012
    Location:
    Oakville, Ontario, CANADA

    Good explanation and entirely consistent with my experience.
     
  15. Fang66

    Fang66 Senior member

    Messages:
    10,701
    Joined:
    Apr 29, 2009
    Location:
    Nihon

    I don't doubt that they do, especially when freshly applied, they are not however waterproofing products, or certainly not DWRs.
     
  16. weewu

    weewu New Member

    Messages:
    1
    Joined:
    Feb 27, 2013
  17. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

    Messages:
    33,334
    Joined:
    Oct 16, 2006
    Location:
    New York City
  18. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

    Messages:
    33,334
    Joined:
    Oct 16, 2006
    Location:
    New York City
    So I understand how scotch grain is a form of correction, but what is it really that gives it the texture? It is a stamp on the leather, correct? Does anybody have a picture of such a method in the process?
     
  19. DWFII

    DWFII Bespoke Boot and Shoemaker Dubiously Honored

    Messages:
    8,241
    Joined:
    Jan 8, 2008
    Location:
    The Highlands of Central Oregon
    

    It's embossed.

    Rollers, plates? Don't know. Could be dependent on tannery.

    The hides themselves are usually a little thicker and can be superficially scarred --the embossing will cover that.
     
    Last edited: Dec 31, 2013
  20. patrickBOOTH

    patrickBOOTH Senior member Dubiously Honored

    Messages:
    33,334
    Joined:
    Oct 16, 2006
    Location:
    New York City
    Yeah, this is probably why it seems to be a bit more water repellant than regular calf. All of the pores are sealed up.
     

Share This Page

Styleforum is proudly sponsored by