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deliming???

Discussion in 'Tanning' started by tuckertan, Feb 24, 2013.

  1. tuckertan

    tuckertan New Member

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    i'll preface to say that i try to do as natural a tanning process as possible, and try to avoid chemicals. i bark tan my hides, and obviously after hair removal neutralizing and completely removing lime is essential and a crucial element to a proper tan. i guess i'll explain my current process, and if anyone has any input, or advice i'm curious to hear about other peoples deliming process. once the hair is off, the hide goes into a tub of about 10 gallons of water, i agitate it regularly, and change the water a few times over the course of a day, then it sits over night, during the night i prepare a fermented bran solution (a drench) and allow the fermentation to take place over 12 hours, where at which point the hide gets placed in the drench and i stir numerous times throughout the day, and is left over night, after 24 hours, the hide is removed, and it's distinguishably more flaccid compared to when it was placed in the drench. at this point it's flesh side is scraped again, then it is placed into a washing cycle in a washing machine, then it goes into it's first tanning liquor.

    i've been reading about using bates, and pancreatic enzymes seem to be the most natural thing to use, and i'm not interested in using pigeon dung, or dog dung. i have a bunch of friend who raise different kinds of animals, and i thought about processing pancreases to utilize the enzymes, which according to a book i have about rural tanning techniques is as simple as mixing three parts minced pancreas to seven parts ammonium chloride. i guess i feel a bit odd about using an inorganic substance with the pancreas, and have read that Sal ammoniac is a mineral that has similar properties as ammonium chloride.. has anyone every processed a pancreas? if so what is your process??

    from what i've read, a bate is done first, then a drench, and then onto the tannin liquor. i'm wondering if it would be more beneficial to sweat hides until the hair slips instead of using lime, which means i can skip a bunch of steps not have to delime.. though my understanding of the deliming process by use of bacterial and enzymatic fermentation also helps to turn the proteids into amino-acids. so if sweating is the process used to remove the hair, is it equally important to bate and drench the hide??

    i think this might be a good one for you oldshaver.... any thoughts????

    thanks a lot for your thoughts and ideas and willingness to share knowledge!!
     
  2. cyclone

    cyclone Posts: 400001

    Deliming is simply removing the liming agent from the skin.

    Several ways to accomplish your goal.

    1. Keep soaking in fresh water frequently changing to wash out or dilute the lime away.
    some folks soak in a running stream so that they don't have to change the water.

    2. Simply dunk it in a bucket of citric acid solution. It'll drop the pH and since citric is a chelation reagent it will bind the calcium in solution.

    3. If you want to avoid liming altogether, learn how to dry scrape the hides.

    4. Sweating, a nice way of saying "rotting" is also an option. Using the hide's own enzymes, if you are lucky the smell won't be so bad, or a combination of that and bacteria, which has a stronger odor..

    Don't confuse being or using "natural" products or methods with being chemical free. Everything that you can touch, taste and smell is made of chemicals. The enzymes you speak of are made of chemicals as are the bark tans you use as well as the very hairs you are trying to remove.

    I do admire your interest in doing things naturally and basic. I'd suggest a visit to the brain tanning website as well as reading Matt Richards book "Deerskins into Buckskins."
     

  3. tuckertan

    tuckertan New Member

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    i think i've been throwing around the word chemicals and natural too much, and after reading both of your posts and thinking about it, you're completely right about chemicals being a crucial aspect of the tanning process. i guess my concern with tanning is using a natural environmentally friendly process. though with the use of so much salt, i've got a pit out back where plants will never thrive again, or perhaps it'll take a lot time to assimilate the salts again.. that's the one thing that i feel really poorly about.

    in some of the books that i've been reading there is mention of bates and drenches as key elements to the tanning process in aiding in the complete removal of lime. the hides that i've been bark tanning do soften up really well, and feel stretchy with a slight oiliness to them. when i compare it to some of the leather i've purchased from commercial tanneries, the commercial tannery hides a ridiculously soft, and plump in both the grain side and suede side. in all of my attempts in leaning all the chemistry to tanning and options for the process i strive for hides similar to ones coming from commercial tanneries, while maintaining a natural aspect to the process.

    instead of using citric acid, i use fermented bran which causes lactic acid to build through the fermentation process.

    i never liked the idea of sweating hides, kinda gross..

    do either of you guys use bates or drenches in your tanning??

    i've read that book a few times through, really good basic book on doing buckskin. another book worth checking out is call "rural tanning techniques".. it was published in 1974 and has so much information in it.. it was my main textbook that taught me how to tan successfully. then other book i have is called "the principles of leather manufacture", printed in 1922, an even more detailed book about the chemistry of tanning. the next book that i want to get is called, "tanning chemistry: the science of leather". can you guys recommend any books?

    i've gone to the brain tanning website, and find that this website has more information and people to talk to that know the depth of the tanning process.. plus their forum is down all the time.

    i thought that bucked was liming the hide.. what's the difference??

    i'm still waiting for OS to answer, i'm still really curious about the bating and drenching process and wondering if it will improve the quality of my leather. i just received some pancreatic enzymes in the mail, and i've got two hides to test it on.. i'll let you guys know how it turns out.

    thanks for all the help, and sorry about my stubbornness.. i really do appreciate all of your advice, and will admit that i'm still learning.
     
  4. cyclone

    cyclone Posts: 400001

    http://search.barnesandnoble.com/Physical-Chemistry-of-Leather-Making/Krysztof-J-Bienkiewicz/e/9780898743043



    There are many different ways to "tan" hides. Every method has it's own set of chemical reactions taking place. You are obviously digging for and finding good information.
     
  5. cyclone

    cyclone Posts: 400001

    From : "Tanning Chemistry: The Science of Leather".

    [quote author=Google Books]

    Even in the 21st Century, the manufacture of leather retains an air of the dark arts, still somewhat shrouded in the mysteries of a millennia old, craft based industry. Despite the best efforts of a few scientists over the last century or so, much of the understanding of the principles of tanning is still based on received wisdom and experience....
    [/quote]


    That says a lot....Don't have this book in my collection but can tell from the intro that it's going to be a good read.

    Thanks
     
  6. tuckertan

    tuckertan New Member

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    i do both and have different formulas and schedules for different results. it also depends a lot on the personality of the hide. bark tanning can also be used to produce a soft supple stretchy leather. i've been curious about using a pre-tan like a sodium lignosulfonate, though it goes against my whole natural tanning thing.. the tannins that i've been using are chestnut (neutralized hydrolysable extract), and quebracho (solubilized condensed extract) i just received a shipment of mimossa, and tara extract as well.. once i powder coat my boiler, i'll be using fir, hemlock, cedar and larch.

    from speaking to the manager in a tanning chemical supply company, who i've been speaking with quite a bit about leather and different ways to produce it, and from reading about it in books, a bate actively removes lime from the hide, as well as breaks down proteids into amino acids, which are more easily tanned with the use of tannic acid, it also allows for a finer grain pattern during the softening stage, as well as releases scud and dirt from the hide. the result is faster and deeper penetration of the tanning liquor. when it's finished in the bate, a drench is used, fermented bran, which utilizes naturally forming lactic acid to complete the process of lime removal, as well as continuing to actively remove unwanted particulate. i've never heard of a bate being used for anything that you mentioned.

    sometimes i keep the grain, and sometimes it comes off under my control and choice. if you've read through deer skin to buckskin, bucking is the process of placing a hide in an alkalizing solution either by using a lime agent (slaked, hydrated, or dolomite, hydrated being the most caustic) or hard wood ash.

    for your process of 'bucking' which isn't actually bucking, it's just that you're taking a hide and putting it in water.. it's obviously going to do a poor job at specifically removing just the hair, because you're creating the perfect environment for bacteria to thrive, which will cause the grain to separate sporadically, cause splotching, or if left for long enough to completely break down the whole hide. it's the same thing as sweating, using a bacterial reaction to induce epidermal separation, though it's not controllable.. whereas with lime and a pH of 12.3, bacteria cant thrive in this environment, i dont think it's a completely bacteria free environment, but it does inhibit growth, just like using salt or soaking a hide in a brine just inhibits bacteria growth doesn't kill it..

    tannins kill bacteria and are resistant to decomposition, they also love to bond to protein molecules which is the foundation of collegian fibers in the hide. once the fibers are coated with tannins they are nearly immune to decomposing and leather can last for centuries if taken care of with simple oiling and waxing. such a cool process to participate with, then use and sew in to practical things to use...

    any thoughts?
     
  7. tuckertan

    tuckertan New Member

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    That says a lot....Don't have this book in my collection but can tell from the intro that it's going to be a good read.

    Thanks
    [/quote]

    i know!! it's amazing!! i'm going to order a copy right now... check out the other two books if you can find them.. i can e-mail you a copy of rural tanning techniques if you want.. let me know.. the other book you posted seems really interesting, i'm going to check it out!! do you have a copy of it? what do you think?? worth the buy?
     
  8. tuckertan

    tuckertan New Member

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    just ordered both of them from amazon.ca 50$ each... so stoked to read them...

    stumbled upon this book too: http://www.amazon.ca/Physical-Chemistry-Robert-G-Mortimer/dp/0123706173/ref=sr_1_8?s=books&ie=UTF8&qid=1361946662&sr=1-8

    "In this third edition, core applications have been added along with more recent developments in the theories of chemical reaction kinetics and molecular quantum mechanics, as well as in the experimental study of extremely rapid chemical reactions."