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Bad African Skins-Why No Stretch?

Discussion in 'Tanning' started by Rhino, Oct 17, 2009.

  1. Rhino

    Rhino Too many irons in the fire will put the fire out!

    Lets start with this.

    From the Greek for glue, kolla, the word collagen means "glue producer" and refers to the early process of boiling the skin and sinews of horses and other animals to obtain glue. Collagen adhesive was used by Egyptians about 4,000 years ago, and Native Americans used it in bows about 1,500 years ago. The oldest glue in the world, carbon-dated as more than 8,000 years old, was found to be collagen—used as a protective lining on rope baskets and embroidered fabrics, and to hold utensils together; also in crisscross decorations on human skulls.[5] Collagen normally converts to gelatin, but survived due to the dry conditions. Animal glues are thermoplastic, softening again upon reheating, and so they are still used in making musical instruments such as fine violins and guitars, which may have to be reopened for repairs—an application incompatible with tough, synthetic plastic adhesives, which are permanent. Animal sinews and skins, including leather, have been used to make useful articles for millennia. Copied and pasted.

    This should be called the "Great African Mistake!" Ever got back an African skin from a tannery, that had the stretch of a piece of plywood? Here is the reason!

    After the harvest of said African game, SOME, STUPID OUTFITTERS, allow the skins to be salted, and placed in the HOT African sun for drying. Some call this "flnt drying", BUT, that is NOT the correct terminology. Flint drying, simply means, drying a skin to the point, that it may crack, when bending. IT DOESNT MEAN, it wont rehydrate! It will take a little longer to rehydrate, but it will rehydrate.

    These skins, are allowed to "bake" in the sun, and when the skin temp reaches 135-140degrees F, the collegen turns into a glue like substance, that is FOREVER damaged! Permanent rawhide!

    A pickle wont penetrate it, so there is NO hope for tanning it. Oil wont penetrate either, so you WONT get any stretch. Some African skins, you will find, to be only "half baked"! Only the best of shavers, can remove this top "glue like" layer, to reveal normal skin structure underneath, only if the species skin is thick enough, for the shaver to get a "bite" on it! On something like a L/S duiker or dik-dik, the shaver MIGHT be able to remove the "bad" layer from the body, and head, but the leg skin, is ruined! You MIGHT could wrap a pencil with it!

    All you guys and gals out there, that have clients that go to Africa, NEED to educate them, on these BAD skin prep practices, to protect THEIR trophies, and YOUR income!
     
  2. jasonb

    jasonb I think I'll keep her

    That's the best explanation I have ever read. I have always known this to be true, especially after mounting a lifesize wt fawn that had baked in the sun on one side. But have never been able to explane it properly.
     

  3. cyclone

    cyclone Posts: 400001

    Excellent OS...
     
  4. bill@hogheaven

    [email protected] New Member

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    Is this what has happened to skins referred to as "grease burnt"?
     
  5. WBB793

    WBB793 New Member

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    Saw this on some safari's in the mid 90's. I talked to several dressers and they also were seeing this.. Man they were the worst. We did get some mounts put together but with tons of carding and pinning!! NO life in the leather. I knew it was something to do with drying and letting the skin get above living body temperature.. Most I have done since I have not seen this again thank god..
     
  6. Nancy C

    Nancy C Well-Known Member

    I wonder if this explains why the legs of this ostrich were so unstretchable compared to the feathery parts, which were (presumably) better sheltered from the sun?
     
  7. Yes Bill it also is refered to as "oxidized"

    working on these often times will take twice as long
     
  8. Monte

    Monte Missouri fur-Limited hair-tanning

    Oldshaver, excellent.
    I have some additional thoughts .
    When the skin reaches the 135-140 temp we have exceeded the shrink temp. of the collegan. Thus permanent damage.
    Both sides of the skin need protection by salting. I think that proper salt curring is the most important thing in hide tanning. The main reason I salt is to kill the glue you mention. Killing bacteria is the easy part. Proper curring the hide for storage and shipping is the hard part.
    The tanners council lab determined that dry salting is only effective to kill the glue to a maximum of 1/4 inch. many parts of African skins are thicker than 1/4 inch. Also the skins dry to fast in that enviroment and do not give the salt brine that is created by the salting process time to soak into the thickness of the skin and cure the glue parts of the skin makeup.
    This means that in dry salting the epidermis side is not curred and subject to air drying. Due to the high temps. and over drying the sebacous glands at the base of each hair root is ruptured and the oil comes on the surface of the skin and continues to water proof and to degrade to a fatty acid along with other natural fat in the untreated part of the skin. This turns into a fatty acid with time and temp. This is grease burn.
    I have not had alot of problem with the thicker skins as far as grease burn goes. Rehydration is more of a problem with the heavy skins because of the layer boundry where salt curred changes to air dried. We have spent a lot of time on this.
    The thinner skins such as oldsaver mentioned have a lot more problem because in the salt shed they do not beam the fat off these thin skins and many just fall apart when soaked. You will notice that only the areas of the skins that have a lot of fat are the areas that fall apart.

    We need to look at a plan that envolves us the tanners , along with clients and the booking agents to assist the Safari companies in changing their attitude about how the skins are handled. We have been sucessful in getting some to do a salt and alum dip prior to dry salting . This does wonders in protecting the epidermis and helps the skin dry a little slower , allowing the salt more time to do its job.

    Maybe we need a taxidermy tanners council??
     
  9. cyclone

    cyclone Posts: 400001

    This is the first and only time I have ever seen grease burn defined...

    Good post Monte...


    This is one of those threads that all of us home tanners should bookmark, copy, paste....commit to memory..
     
  10. hoytman

    hoytman UTA Member

    If I ever go to Africa to hunt, I am bringing 100lbs of Salt in my luggage, and hunting in flip flops and shorts that I wore their.. I'll salt my skin, flesh, turn and salt my own stuff.. If it isn't legal to do so..., I am NEVER going to Africa to hunt animals..
     
  11. Glen Conley

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

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    Someone be brave and tell us what is going on in these two photographs.
     

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  12. Glen Conley

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

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    While someone is into explaining, here's a little more photographic proof. Tell what's going on here.
     

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  13. Rhino

    Rhino Too many irons in the fire will put the fire out!

    Monty, that was excellent! LOVED IT! Been away, since SAT.

    Glen. I think the first 2 photos, are from a skin, that was as I described in my origional post. The skin structure was effected by heat, but NOT totally lost. There is enough of the origional skin structure to hold the skin together, but NOT enough, to pickle, tan, and oil, to provide a decent mount, from lack of stretch.

    The next 2 photos, in my opinion, are showing a grease-burnt skin, that will rip apart, with the slightest pressure.

    Glen, talk to me!
     
  14. Monte

    Monte Missouri fur-Limited hair-tanning

    Glen, I think I see familiar images here, but I am not sure. I will keep looking and thinking. My experience through the microscope is limited.

    Thanks to cyclone and oldshaver for your comments.
     
  15. TonyR

    TonyR New Member

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    My wife and I were lucky enough to be able to afford a Afican Hunt before our boy was born. Its one of the greatest things you could try.
    When we were ready to go, the outfitter brought his taxidermist to meet with everyone on the trip and set up your hides and/or mounts for the U.S. We had our 15 animals and 1 monkey tanned in Africa to be mounted in the U.S. Please don't make this mistake. The monkey was destroyed from the tanning process and all the other hides had to be sent in and "re-tanned" or hydrated to be able to be worked for good mounting. We originally thought it was quite a savings but soon realized wrong. Also, I have heard several horror stories about the quality and longevity of getting your mounts done there and shipped. Please research this carefully if you would get the chance to go or go back. I am not a taxidermist and do not work for one, just trying to help out.
    I have also heard of people that have no problem with their mounts coming back tanned from there, but maybe they mount in a different manner?
     
  16. Excellent point we have also had similar problems with having to "retan" what was tanned in africa, also had customers who had trophys mounted there only to have them ruined in shipping, bounced around in the crate, one had lid screws through top of the lid and into the mount, another had a forklift fork go through the side of the crate and destroy the mount inside. The loading docks can destroy finshed mounts after you have paid for your trophy good luck getting them reimbursed.
     
  17. Glen Conley

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

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    Oldshaver, you're getting dangerous.
    I deliberately picked out photos that shared appearances with what you had described initially. A guy could just about write a small book around those four photos.

    You're on the right track with the first photo. Look at the second one a little bit closer. Go for a better answer.

    Three and four are mimics that help to explain your copy and paste.
     
  18. Rhino

    Rhino Too many irons in the fire will put the fire out!

    Ok, I will throw a hail Mary, and say, that the skin structure, in the second photo, seems to be darker, and is allowing less light to pass through, for the photo?

    Could this be a chemical burn, or did you get hold of a smoked skin sample? The reason I asked about the smoked skin, is, I dont know what area of Africa they come from, without researching it, but for some reason, they love to smoke Bongo skins!?

    For those of you that havent been around the forums for very long, GLEN, is da MAN!
     
  19. cyclone

    cyclone Posts: 400001

    Looks like the collagen is simply melted..sun dried skins?
     
  20. Glen Conley

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

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    Looks like the collagen has simply melted it does'nt it?

    Cyclone, these two photos are your's until we get something figured out.

    What you were looking at was an acid swell whitetail cape.