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. 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!