Cape fell apart like wet paper bag?

Submitted by Bill on 4/21/05 at 11:47 PM. ( )

I recently purchased a whitetail doe cape that was comercially tanned. It had to be the nicest doe cape id ever seen. I soaked it in room temp water for 45 minutes and when I pulled it out of the water it just fell apart like a wet paper bag. Has anyone ever seen this? Did I do something wrong?

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Old cape...

This response submitted by Drew on 4/22/05 at 12:00 AM. ( )

It must have been an old cape. I bought a whitetail cape from a guy, commercially tanned, looked nice. Through it in the water and it too fell apart just pulling it from the water. It fell apart within 5 minutes of soaking. Get your money back. Dry tanned capes don't keep forever.

Sounds like acid rot.

This response submitted by Todd B on 4/22/05 at 12:02 AM. ( )

I had a bear skin and also raccoon skin do the same thing. I was told by a few guys that it was acid rot. What I believe happens is the skin does not get neutralized well and the acid keeps working on the skin even after the tan. When it is soaked up it falls apart. There is nothing you can do to save it. No it is not something you did.

Todd B

Another X-File?

This response submitted by Glen Conley on 4/22/05 at 1:58 AM. ( )

Those pesky ail yuns again?

Scully, the truth IS out there!

POP QUIZZ for Griz!

skin is not neutralized

This response submitted by Laurier on 4/22/05 at 9:03 AM. ( )

it does not matter if the skin is wet or dry tanned. If the acid is not neutralized from the skin it will eventualy fall apart.
VERY FEW tanneries neutralize the skins. This is the reason that your fur coats have to go in cold storage in the summer.

Another HINT!

This response submitted by Glen on 4/22/05 at 9:25 AM. ( )

1. CH2O2
What is it?

2. What does it break down to?

3. After it breaks down, what is left where it was?

4. What did it do to a skin BEFORE it did number 2? (To say that it also did a Number 1 will not be accepted as the answer.)

The POP QUIZ for Griz as of yet has not been answered.

Its grain alcohol

This response submitted by ? on 4/22/05 at 11:18 AM. ( )


Ok, I will play

This response submitted by Bowfin on 4/22/05 at 11:21 AM. ( )

Isosafroledibromine (CH2O2:)C6H3.CHBr.CHBr.CH3

100g Isosafrole is diluted with 100ml petrol ether. Under cooling with ice a solution of 100g bromine in 100ml petrol is added drop wise. If cristals of the Isosafrolebromide are around, some cristals are added to initiate cristallisation when the addition of bromine has finished. The flask is put on ice and the lower part consisting of the dibromide gets solid after some hours. Yield 203g. The dibromide does not easily cristallize. mp is 52-53°C. [N1]

Isosafrolebromhydrine (CH2O2:)C6H3.CHOH.CHBr.CH3

100g Isosafroledibromine are dissolved in 300ml acetone, water is added as long as the solution stays clear (appr. 50ml). In addition, 16g of marble pieces (CaCO3) are added to catch up the HBr which is produced by the hydrolyse of the dibromide. Carbon dioxide develops already in the cold. The mixture is heated then 2 hours on a hot waterbath. After 2 hours the aqueous CaBr2 solution is removed and another 40ml water is added. 2 more hours the rxn is heated on a water bath. Then the acetone is removed by destillation. The oily Isosafrolebromhydrine is extracted with ether [N3], the ether solution is washed with water and dried in vacuum. Evap the ether. Yield 98%. The Isosafrolbromhydrine cannot be destilled in vacuum but will be used as it is for the next step. [N2]

Isosafroleepoxide (CH2O2:)C6H3.CHOCH.CH3

100g Isosafrolbromhydrine are disolved in 100ml alcohol. A solution of 25g KOH in 200ml alcohol is added. Immediately KBr seperates. The alcoholic solution is refluxed on a waterbath to complete the reaction. [N4] Most of the alcohol is then removed by destillion. The solution is poured into water and the Isosafroleepoxide extracted with ether [N3]. Ether solution is dried and evaporated. Yield with respect to the dibromide is 88%. The Isosafroleepoxide is a colorless, good smelling oil which boils between 143-147°C under 12mm pressure. [N5]

3,4-Methylenedioxyphenyl-2-propanone, (CH2O2:)C6H3.CHOCH.CH3 i.e. Isosafrole-2-propanone, MDP2P

The conversion of the Isosafroleepoxide into the ketone starts when the epoxide is heated to 220°C in a flask equipped with a air-cooled condenser. The temperature jumps up quickly to 280°C. When the exothermic rxn has finished, the mix is refluxed for a short period of time. The first destillation under normal pressure yields a colorless, almost non-smelling oil, which comes over between 280-290°C. Under 10mm pressure it boils between 149-151°C. Yield 80% [N6]

Isosafrole-2-propanone-oxime (CH2O2:)C6H3.CHNOHCH.CH3 [N7]

3g ketone are solved in ethanol, 3g Hydroxylammonumchlorid, solved in a minimum amount of water, are added and the combined solution is make alkaline with concentrated Na2CO3 solution. After standing (hours..) and dilution with water, needles of the oxime seperate. They melt at 87°C. Recrist. from ethanol or et ether.


Hörig uses ether instead of pet ether for the bromation. The dibromide is used as it is for the next step.
Mannich adds the calcium carbonate during the rxn. For the preparation of the corresponding asarone-bromihydrine the Höring approach with pieces of marble should work better, since the Hbr is removed when it's produced.
Any other non-polar solvent should also be fine.
No duration specified by Höring.

There are of course other methods around to get to the epoxide, e.g. per-acetic methods or oxidation with H2O2 in MeCN/MeOH.
The conversion can also be performed by mixing the Isosafroleepoxide with GAA and adding some drops of H2SO4. But the main interesting point is, the epoxide does not explode but re-arranges into the ketone! And: No need for Li-salts and ethyl-acetate for the rearrangment. Just use HEAT The per-acid method will not likely work for asarone.

This is more for information. Oximes may however also be reduced to the amine, there are examples on the chief bees site. The anethole-oxime comes in a two isomeric variants with mp 61-62°C and with a mp of 72-74°C.

Where you guys paying attention to Bowfin?

This response submitted by Glen on 4/22/05 at 1:19 PM. ( )

Good answer, illustrates other uses of CH2O2, but that's not the one we're looking for. We are doing dead animal skins here, not designer drugs. LMAO

Let's start with question #1 again, but read it and answer it in it's simplest form. Same thing with #2 and #3.

As you can see with Bowfin's answer, #4 can get REAL tricky, but again we are looking for only the simplest and most obvious answer.

What are you trying to do, Bowfin, give these guys a heart attack? I can imagine how big Todd's eyes got when he read that.

1...Formic acid

This response submitted by cyclone on 4/23/05 at 6:54 AM. ( )

2. Formaldehyde....methanol.. carbon dioxide..
3. Don't quite understand....usually acids remove the "untannable proteins"...Aldehydes left behind such as formaldehyde are tannins i.e. capable of crosslinking tannable proteins...
4..?Again..confusing...remove the untannable proteins and ready the others for crosslinking.

and here's the most important ? for bill

This response submitted by paul on 4/23/05 at 11:19 AM. ( )

did you add a nice handfull of salt per gallon of water in your rehydration solution? another thing, if your not getting your dry tanned capes mounted within a yr , your best off rehydrating them and then into the freezer with them, most commercial tanneries recomend mounting within a yr. although i have mounted some deer and bear that were in a dry state for over 6 yrs.

Anytime now....

This response submitted by seekthewisdom on 4/25/05 at 9:54 PM. ( )

feel free to reply....

Free reply...........

This response submitted by Glen Conley on 4/26/05 at 1:22 PM. ( )

1. CH2O2
What is it?

Formic acid is the correct answer.

2. What does it break down to?
CH2O2 yields CO + H2O, or carbon monoxide and water

3. After it breaks down, what is left where it was?
Nothing is left where it was, it's an evaporative.

4. What did it do to a skin BEFORE it did number 2?

It heated it

This response submitted by oldshaver on 4/26/05 at 9:37 PM. ( )

Hence the term acid burn.

Gold Star by oldshaver's name!

This response submitted by Glen Conley on 4/27/05 at 2:04 AM. ( )

I wouldn't be a bit surprised but what he hasn't had first hand experience at one time or the other on his own skin.

To build on what he just pointed out:

From memory, the melting point of most proteins, as crystalline organic solids, is 50 to 90 degrees C., or 90 to 162 degrees F. Again from memory, the melting point of the proteins that make up collagen, glycine, proline, and hydroxyproline has been reached by 70 degrees C., or 126 degrees F. However, the proteins are in a state of disassociation at 100 degrees C, or 212 F. You might want to double check my numbers, just in case I'm off a few degrees.

Do you think proteins care as to what the heat source is before they begin to melt? Exothermal chemical reaction, or radiant, or convection? Once melted, and cooled back down, then what?

Kinda makes a person think in terms of a primitive hide glue doesn't it?

To Hyphen Guy, correlate the above. One thing that you will need to do is to find out that when the three structural proteins have disassociated with formic acid, and then rebonded, the hydrophilics are left turned out. You might even be able to find something of that description in writings from someone in the durable leather goods end of the world, I believe the terminology used there is "sheeting" to describe the end result. That's a hard bond to break. All that cross linking. That's why I prefer working with linear bonds.

The photos I used in the Pop Quiz for Griz! were from a citric acid pickled cape. In spite of the state of disassociation, I was able to reorient as linear structures.

With it being pointed out that the hydrophilics are left turned out, that should immediately make a light bulb come on in someone's head. Once evaporatives are gone.........the hydrophilics remain exposed, but just dry. What happens when they come into contact with water? Simple answer, it's the same principle that allows you to make J E L L-O!

Hell's Bells, I could sit here and wear my typing finger out just pointing out variables. From now on I have a new rule, instead of doing all this typing......I'm just going to blame it all on ail yuns.

That's pure ALCHEMY!

This response submitted by cyclone on 4/27/05 at 10:34 PM. ( )

No disrespect intended to anyone::::

Adding acid to water is indeed exothermic and releases heat. It only releases that heat on the initial mixing. There is no way that those temps are reached at those concentrations with formic. Now dump concentrated sulfuric in there and maybe just maybe it will heat enough to cause some damage. (By the way don't "dump" sulfuric into any solution as it will splatter...ALWAYS add any acid to water and never the opposite....and do it slowly).

Proteins are first "denatured" by heat. That is; they deform from their normal configurations. See what happens when you drop a raw egg (sans shell) into a hot skillet. It doesn't fall apart, on the contrary it solidifies.. Yours is an interesting hypothesis; however.

When a perfectly good hide goes to pieces after tanned as mentioned I'd wager to hypothesize that either the pickle solution was too concentrated with acid and/or an oxidizing agent or acid was introduced. Sulfuric and Nitric acid will cause a hide to fall apart. Nitric acid is such a strong oxidizer that it will literally "digest) or cause the hide to fall apart before your eyes. Nitric is used widely in analytical chemistry for "digesting) organic factions out of samples so that the remaining elemental metals can be analyzed. Any sulfates, sulfites, nitrates or nitrites left behind or introduced will oxidize the fibers in a hide. Even after tanned and finished these salts will continue to oxidize the fibers when water is present. Water vapor absorbed from the air is enough to keep the reaction going. Chromic acid is a potent oxidizing agent. So strong, in fact , that it was used for eons for cleaning chemical glassware..It is no longer used much, if at all, because of it's poisonous nature and EPA regulation. Chrome is also used as a crosslinking agent....especially in hide tanning...Hydrochloric acid.....well, what does it do in the digests....mostly proteins...

Formic acid partially dissociates in solution meaning that some of the hydrogen ions are separate and mixing with the water..An equal amount of the formate ions are separate as well...Formic acid by its nature is volatile meaning that it readily evaporates...much like acetic acid, vinegar, it has a pungent characteristic smell. When mixed in solution, hydrogen bonding prevents it from volatilizing as rapidly. Good reason to use it in a separate location, not the basement and keep the pickle covered.
Formic acid in solution will also form the sodium formate salt.

There are a ton of other reactions going on in that pickle as well. Ever get that ring around the container...thick soap like material....That's sodium sterate..the same stuff that causes "ring around the tub" and shower scum...

Normal table salt, sodium chloride, never did, never will and can never ever have anything to do with neutralizing an acid. It has no effect on pH whatsoever...In preventing acid swell it simply creates an equilibrium with the salts contained within the tanned hide fibers. Without salt, osmosis comes into play and water rushes into the fibers as salt is drawn out in an effort to reach equilibrium. This causes the swelling... Add'll go away...

again...No disrespect intended to anyone but that's the way I see it....


This response submitted by oldshaver on 4/30/05 at 9:54 AM. ( )

Formic is the best acid for our purposes, and I agree with everything you said. In this case, not enough salt, too long without enough salt, = acid burn.


This response submitted by os on 4/30/05 at 10:01 AM. ( )

Glen was asking a question based on his writings, hence, my answer based on his writings, not necessarily my personal experiences.

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