Summary
This is the result of research and experimentation done by chemistry students and their teacher at Niobrara County High School in Lusk, Wyoming.
A portion of an antelope hide was de-haired with lye, fleshed, pickled with sulfuric acid, and tanned into leather. The tanning agent used was Lutan-F. This is a commercial product, thought to be mostly aluminum chloride with small amounts of other substances.
The process took 6 days to complete.
Result
The final product is a nice piece of leather that is quite soft and flexible. .
The leather is very thin with a nice buckskin tan color.
Several cracks appeared on the hair side.
A very thin membrane like layer can be peeled off some areas on the hair side.
The leather may not be as strong as it should be. It feels like it would tear easily.
It has several holes in it. One from a bullet and several from the fleshing process.
Leather tanned with Lutan-F should not be rinsed much when finished.
Procedure
Hide
The unprocessed hide was obtained from a taxidermist. It was the back 2/3 of an antelope hide from which the cape portion had been used for mounting.
It had been skinned carefully and had almost no flesh attached to it.
It had been salted and stored for some months but was still flexible.
De-hairing solution (60 grams (2 oz) of lye(NaOH) in 5 gal water)
The hide was washed in soapy water, rinsed, then soaked in clean water for 2 hours.
It relaxed well, becoming soft and pliable.
It was placed in the lye solution and stirred frequently.
After 24 hours, the hair would slip from about ¾ of the hide.
The hair that slipped easily was removed by pushing it off with a small wooden block.
The hide was placed back into the lye solution for another 24 hours.
The remaining hair was removed. Some was still tight and had to be pulled off by hand.
The de-haired skin was washed in several changes of clean water for 30 min with agitation.
Pickling solution (15 ml of 98% sulfuric acid and 300 grams salt in 1 gal water)
The hide was soaked in the pickle bath and stirred frequently for 24 hours. By then it had turned white throughout.
It was rinsed and fleshed with a fleshing wheel (this process managed to produce a few holes in the hide, but all fingers survived).
Neutralized in baking soda and water 15 min with agitation.
It was drip dried and weighed. The damp weight was 2 pounds.
At this stage, the hide seemed very thin.
Tanning solution (60 grams (2 oz) of Lutan-F and 2 cups salt in 6 quarts of water)
The hide was soaked in this solution for 24 hours with frequent agitation
It was removed and rinsed in clean water for 15 min with agitation. (probably the reason it became stiff)
The rinse water became cloudy (meaning something was being washed out?)
The excess water was blotted off and neatsfoot oil was applied to the flesh side of damp hide.
It was dried on a rack in front of a fireplace (care was taken not to allow the hide to get more than pleasantly warm) Drying took 2-3 hours.
It was "broken" frequently while drying by dragging it over the edge of the counter top and rolling it between the hands.
Some cracks began to appear on the hair side at this point.
It became "tinny" when dry. It was assumed that it was not fully tanned so -
Back in Lutan-F for another 24 hours in an attempt to make it softer.
The leather was rinsed 15 min with agitation (same mistake again).
Neatsfoot oil was applied again.
It was partially dried near the fireplace then placed in the clothes dryer on low heat and tumbled with an old shoe to help break it.
The leather was still tinny when dry. (little different from last time)
Back in Lutan-F for 6 hours
This time it was rinsed very lightly (a couple dunks in each of 2 changes of clean water).
It was dried near the fireplace (no more oil and little breaking).
The leather is much more flexible this time and has a nice feel to it.
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We would appreciate any constructive criticism of the process we used to tan the antelope.
Any thoughts on what caused the cracks. It has happened some on some other hides we have tried.
We have started using hydrochloric (muratic) acid for pickeling and may have some improvement.
Could it be the lye that is causing the cracks? Or they just bad hides?
Antelope are not considered a good choice for trying to produce leather. Most of them are taken during the warmer months and the flesh is very thin. Subsequently the leather is also thin and weak.
I guess I should ask a few questions first. You used Lye - but did you "kill" the effect of the Lye after you dehaired? I was looking for ph readings in your process, but didnt see any. The Lye could seriously affect getting the proper readings needed in your process.
The cracking on the "grain side" of your skin is probably because in dehairing you didnt leave it in your dehairing solution long enough to allow the epidermis to pulp and be removed. Also plain neatsfoot oil is not a very good leather oil. It will only lube the surface and has very little penetration.
The next time you dehair - allow the skins to remain in the dehairing solution until the hair falls off at the touch. Dont do a little bit and go back later, DO IT IN ONE OPERATION. Along with it, the epidermis should also be pulped and ready to be skimmed off.
Also dont use heat in a dryer to dry it after oiling. It may drive out what little oil is on the hide surface. In fact, its better to tack out the skin loosely and allow it to dry, and then work it soft.
Good luck with your next project!
Bruce Rittel
Rittels Tanning Supplies