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Science behind tan penetration

Discussion in 'Tanning' started by DSalters, Jul 24, 2007.

  1. DSalters

    DSalters New Member

    I've been thinking about the proper penetration of tans into a hide. If a hide is layed out (hair side down) and a cream/brush-on tan is brushed on, HOW is it that the tan is able to make it all the way through to the dermis on the hair side? Now, I know that it DOES work, I've done it and countless others do try or use these methods, but I am hung up on HOW. It seems that once the tan has been brushed on the surface, that portion of the skin is already tanning and would thus block any further penetration from occuring. The only logical (and maybe flawed) explanation I would expect is that the chemical reactions are not taking place as fast as it takes for the tan to soak (or be drawn) through all of the cells.

    I once had a doe hide/throw in submersible EZ-100 for a few hours but I just could not keep it submerged well enough to allow me to leave it comfortably (because it just wanted to float and I did not have the best device to keep it down). After a few hours, it came out and McKenzie brush on tan was applied. It tanned wonderfully. Since sumbmersible tans take upward of 24 hrs and brush-ons around 6-8 hrs, a higher concentration rather than a dilluted on clearly penetrates faster, but the submersible still allowed the brush-on to penetrate through what had already taken place.

    Thanks in advance for all input.
    -Daniel
     
  2. oldshaver

    oldshaver Guest

    It tanned wonderfully? Did you do a hot water test, to test the T's temp? At what temp did the hide curl? It will probablly be saturday before I have enough time for this post, but without testing, you have no idea how well it tanned. If your going by stretch, etc, dry preservative will do the same, and will stretch like hec. See yall this weekend.
     

  3. DSalters

    DSalters New Member

    "Wonderfully" in the sense that all hairs set tight and the hide dried fairly soft with minimal breaking necessary. Instead of saying it "tanned wonderfully", I should have said "I was very pleased with the outcome following tanning."

    I look forward to your responses this weekend.

    Thanks!
     
  4. George

    George The older I get, the better I was.

    DSalters, chemically, it's called "osmosis". (In physical chemistry and biology, I THINK the more proper term is "endosmosis".) When you salt a hide, water is vacated from the cell structures (I know Glen Conley had a much MUCH deeper explanation, but this is tanning for dummies), the acidic content of the tan gets sucked up into the hide cell structure. The submersible would have worked just as well floating, but most of us tend to have a greater comfort level it it's completely submerged.
     
  5. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

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    The physical science principles are:

    Gravity takes things DOWN.

    Water runs DOWN hill.
     
  6. George

    George The older I get, the better I was.

    ROTFLMAO. Glen, only you. Does the word "succinct" mean anything to you. LMAO
     
  7. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

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    "succinct" will be found after skun and snuck in the dickshunairy.

    I came in to post some more reference photos, I was getting ready to go get the guy a picture.
     
  8. DSalters

    DSalters New Member

    Yeah, that's pretty succinct. Maybe I need to rephrase my original question in a more succinct form:

    Say, for example, a deer hide is three inches thick, will it keep accepting a brushed-on tan until it cannot hold anymore (like a sponge)? OR does the cellular structure that first receives the tan soak it up and block-off further penetration to the remaining 2.5" of hypothetical hide?

    Glen, when you spill water on your floor, do you normally flip your floor upside down so the water will fall onto the sponge. That way, you would have gravity AND the soaking action of the sponge on your side! :)

    -Daniel
     
  9. George

    George The older I get, the better I was.

    Daniel, first off, if your hide is 3 inches thick, you'd better have it in the pickle and not in the tan because you need to shave off about 2.8 inches of it. I've heard of "overtanning" or leaving a tan in the solution too long. It's not something I'm familiar with. I always tanned and check the penetration by slicing the skin. When the tan was all the way through, it was removed. An old method was to use your thumbnail. When you press it into a tanning hide and it doesn't come back out, the hide is tanned. I don't think the major tanneries use that method either.
     
  10. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

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    I would let it evaporate.

    I can understand why major tanneries don't like that method. They would have to hire employees that are all thumbs to maximize testing, otherwise two tests would be all that could be performed.
     
  11. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

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    If a live deer had been running around with this hypothetical hide, then it would be possible, and probable for a brush-on compound to penetrate.

    The first thing you need to do is to forget what you "think" you know. Blunt, S.O.B., ain't I?

    Now, create a mental image. Start laying up pieces of cloth, one on top of the other, once you have matched the thickness of the hypothetical hide, would water be able to penetrate all the way through the stack? Explain your answer. Remember, you started this, not me.
     
  12. cyclone

    cyclone Posts: 400001


    Pretty good answer right there.

    Capillary action. see: http://en.wikipedia.org/wiki/Capillary_action

    Dip the bottom 1/4 inch of a paper towel into some water, or oil, or tanning solution. You can watch water travel against gravity.
     
  13. msbraintan

    msbraintan New Member

    I can't tell you all how much acidifying skins has come to mean for my braintanning.. big diff..big diff.. now just to get all the other ducks in order, lol..

    [​IMG]
     
  14. msbraintan

    msbraintan New Member

    well.. i realize that my post was way of your subject however it took me eons to figure out that to get the oils to adhere to the fibers in the skin i needed to alter the raw skin.. now I can follow through with the smoke that is used to tan my thoroughly softened skin.. I had thought that the acidification had more to do with neutralizing the bucking solution than by prepping the skin for the oils.. salting skins can only help... as in wetsalting and this is another total non tradish thing, right?? so sorry ya'll for intruding and changing the subject.. just interesting to see how it all relates and sometimes it DOESN"T.. lol.. so sorry!
     
  15. George

    George The older I get, the better I was.

    I'm not sure what "non-tradish" is supposed to mean. Salting is always a requirement for good leather UNLESS you can affort the luxury of allowing a hide to flint harden. Most can't as it's usually too slow a process except in arid countries.
     
  16. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

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    Nice addition to the thread, msbraintan.

    Uncle George, I can't believe you said that! That piece of leather I sent you a year or so ago was done without salt, and it was never dried either. That actually ties back into this thread pretty well, as far as Daniel's original question. Speaking of Daniel, did he leave? I've got photos in the wings, just waiting for him (now watch Hudson say he doen't understand my photos).
     
  17. DSalters

    DSalters New Member

    I'm still around, Glen; sorry for the delay.

    I've cleared my mind of all I think I know (as you've said so bluntly but perfectly all right with me), and I've stacked pieces of cloth to a thickness of the hypothetical hide. If I was to pour water onto it, the stack would keep taking water until no more could be held. However, a different substance, perhaps not. Say I dumped molasses on it...seems like there would come a time where it would stop accepting anymore fluid NOT because it is all soaked up but because it is gumming up too much due to drying. (I know, I am entering another variable in here, but with something of that nature, it seems necessary.) Perhaps a tan works this way too??? I'm sure you have a logical explanation because you have studied and seen the make-up of mammal/deer skins. I just can't help but think that there will come a point where too thick of a substance will stop being accepted by a hide. However, I was supposed to forget everything I think I know though.

    You're right, I started this, and I'm totally OK with it because it's been bugging me to not totally have my head wrapped around it.

    Bring on the pictures...what Glen Conley posts would be complete without them?!
     
  18. DSalters

    DSalters New Member

    Guess I didn't REALLY explain my answer, like you suggested, did I?

    The water would be soaked into the network of cloth. What would not be, would pass through because it would no longer have the ability or spaces to hold the water. Plus, the water would not dry up and block up any passageways.
     
  19. oldshaver

    oldshaver Guest

    I see alot of good explanations on how a tannage is introduced into a skin, but what is keeping it there, along with the oils necessary for lubrication? H-bonds, ionic bonds, covalent bonds? These are the reasons, I cant see a paint on, or an all in one submersible, being more than a short term preservative. Maybe someone can make me believe otherwise.
     
  20. cyclone

    cyclone Posts: 400001

    Since I don't know what's in the popular 'paint ons' I cannot comment on them. But I'd answer yes to all three of the bonds indicated! The collagen latticework is complex. Crosslinking occurs between the strands as well as within ....Plenty of active sites for all of the above although covalent is most preferred.

    Many tans are also pH dependent. pH not right and the tan will not take or take too soon..