A discussion of PH
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Author Topic: A discussion of PH  (Read 4044 times)
Jon S
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« Reply #15 on: December 24, 2009, 10:46:12 AM »

This is a great thread!
I always neutralized for 20 minutes and never ever thought about taking  a ph reading of the hide. At least my liquatan does always absorb into the skin quickly. I use pickling crystals and never have a ph below 2 at all (maybe when I first mix it).
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CLIFFTAX
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« Reply #16 on: December 24, 2009, 10:49:11 AM »

never ever thought about taking  a ph reading of the hide.

I am blown away by this statement as it is not the first time I have read it on here. I am glad it has been brought up in this thread. I always assumed anyone who home tanned knew this as they knew to neutralize.
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cyclone
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« Reply #17 on: December 24, 2009, 10:50:27 AM »

I'll do it that way from now on...thanks for the tips.
I noticed in another post concerning Lutan F that the guy using that method had an aquarium pump type thing that he used to keep the water moving.
Would there be any benefit of having one for a neutralizing bucket?
Or even in the pickle for that matter?
just curious as I've read that agitation is one of the key components that old shaver has mentioned...
just wondering about scaling it down for a home tanner.

Yes, it will help.  The neutralization is taking place at the surface of the hide as well as within it.  Agitation or circulation of the solution brings fresh bicarb to the skin surface where it is needed.  


I am one of the guilty ones when it comes to a very low PH. I try to keep it at 1 at all times or at least start off like that. When it comes to neutralizing I realize the 20 minute soak is not going to cut it. I go for an hour or more on deer hides and almost use a whole box of soda doing it. As far as salt I add a pound and a half per gallon of acid. I also keep my pickle solutions at a temp of almost 70 degree's if I can. What blows my mind when using Lutan F, is that they want the hide at a PH level of 5 to 6 before you place it in the tan. I get freaky when I approach those numbers. But it all turns out good and my tanning success is up there.


If it ain't broke....don't fix it...
Got a good method?  Stick with it...but if you change anything in your pickle...be prepared to deal with it...

OS is trying to help us understand that what goes on in a pickle is more than just pH...
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Baking soda is sodium bicarbonate. They are one and the same...

Re-hydrate! It is an important step.


Spell chek.....not jest enother perty button.
Jon S
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« Reply #18 on: December 24, 2009, 10:55:11 AM »

Nope, everything I have ever read about neutralizing has always been based on time, along with the dangers of neutralizing too long.  
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livingtrophytaxidermy
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« Reply #19 on: December 24, 2009, 10:10:45 PM »

what wiil happen if you neutralize too long? i guess hair loss???????
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oldshaver
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« Reply #20 on: December 24, 2009, 10:31:04 PM »

Livingtrophy, Im hoping Glen Conely will jump in here, by Saturday. He probablly has some photos for us, on this topic?

Cyclone, your actually helping me understand a few things! ;D  Keep it up!
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craigjw
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« Reply #21 on: December 25, 2009, 12:06:03 AM »


Craig. what EXACTLY do you put in your 8 gallon pickle, and EXACTLY how do you neutralise? Yes you can have too much salt.





[/quote]

I do 2 deer capes with 8 gallons, and neutralize with baking soda, usually soak for 30 minutes and check ph of skin when done

When adding salt while adding acid, how much do I need to add, at what point is it too much?
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craigjw
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« Reply #22 on: December 25, 2009, 12:08:47 AM »

Cyclone, you said to keep track of how much acid I add and start with that.  I would guess that would make it start very low, is that OK?
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cyclone
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« Reply #23 on: December 25, 2009, 06:14:51 AM »

If your pH is rising and you have to add more during the course of the pickling stage, That rise is due to to the acidic protons being neutralized whether by something within the hide or on the hide.    If you start out with 10 oz of your acid at the beginning and add another 5 oz the next few days to bring it back down,  Why not start out with 15 oz at the beginning?   

Different acids affect pH differently.  I can add a truckload of formic acid (a weak acid) with the confidence that the pH will not drop much below 2.  It is the nature of formic acid.  I know that if I add 2 truckloads of formic, I might get the pH below 2 but I still have 2 truckloads of acid to neutralize.
Only a certain number of the formic acid molecules will go to work while the others remain idle but at the ready...

Use a acid like hydrochloric (a strong acid)  and all of the available protons will go to work.  Hydrochloric has no lazy protons.  It will drop the pH like a rock...


Notice (a weak acid) and (a strong acid) in parens...  To a chemist these notations have special meaning.  Strong acids, by definition, donate all of their acidic protons when in solution..  Weak acids only donate so many acidic protons the others are held tight to the acidic molecule..



Chew  on that awhile, I have some Christmas cookies to eat...

MERRY CHRISTMAS ALL...

cyclone..
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Baking soda is sodium bicarbonate. They are one and the same...

Re-hydrate! It is an important step.


Spell chek.....not jest enother perty button.
craigjw
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« Reply #24 on: December 25, 2009, 09:08:06 AM »

Whats the best acid to use, strong or weak.  I have used citric and safety acid.  I use only safety acid now, it seems like a weak acid and easier to neurtalize.  So is it good to be easy to neutralize?
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msc
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« Reply #25 on: December 26, 2009, 07:24:57 PM »

I was also wondering of ill effects of neutralizing for too long
if left in too long will the ph get high enough to cause any problems
I just assumed this was the key to the time frames always given in the instructions
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MSC
oldshaver
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« Reply #26 on: December 26, 2009, 08:23:33 PM »

Now, did a few of you understand this? If so, how much more acidic is a pickle, with a PH of 1.5, than a pickle with a PH of 2?


OOH, ME!  ME!  Pick me OS!  (waiving hand furiously)...


Just havin fun OS...   the correct answer is:   The difference in the amount of acidic protons (H+) or  hydrogen ions between a pickle of pH 1.5 and pH 2 would be 5X.  For each 1 pH unit of variance there is a 10 fold difference in acidic protons in solution.

This gets more complicated with different acids, however...(fodder for another topic)

OS I would assume that tanneries neutralize entire batches of pickle with hides included.  For us home bucket tanners, at least for those like me that re-use pickles, a lesser amount of bicarb is needed to neutralize just one cape when you pull it and put it into another bucket. 

Somewhere along the home tanning historic time line someone had to come up with a "fool proof" way to neutralize acids.  That recipe works well if you have the exact conditions that the formulator had when they derived it.  What they didn't take into consideration is how much acid is used up by the hide, how differences in the ways hides are handled can affect the pH of a solution, how any water other than pure distilled water affects the initial pH of the solution. 

Collagen, the basic foundation of hides, has a very complicated structure.  While acid helps to protect some chemical groups from falling apart, it can destroy other bonds.  Salt comes into play to help protect those bonds.  There is a fuzzy line between just the right mixtures.  Too much acid yields a rubbery hide, Too much salt, plastic-like consistencies.   

George, you're exactly right in doing it that way for bucket tanning.  I know I don't have to tell you this but it is your decades of experiences that guide you..You've done it more than most here..

Craigjw...why not figure how much total acid you've added with this batch and start out with that much acid for the next batch...adjust your starting formula...You shouldn't see those big fluctuations. 

Gotta run, Santa's calling, more later.... ;)



Thanks for this post Cyclone! You have got me studying like hell now!

http://www.chemtutor.com/acid.htm#pkabx
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cyclone
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« Reply #27 on: December 26, 2009, 10:50:41 PM »

Whats the best acid to use, strong or weak.  I have used citric and safety acid.  I use only safety acid now, it seems like a weak acid and easier to neurtalize.  So is it good to be easy to neutralize?

The best acid to use is the one that you have the most success with.  I like formic.  I have a good track record with it.  I have also tried a mix of formic and safety with great results.  I've never used citric. 

You have to watch any pickle mixture when you first add your capes.  Test the pH often and adjust as needed.

I was also wondering of ill effects of neutralizing for too long
if left in too long will the ph get high enough to cause any problems
I just assumed this was the key to the time frames always given in the instructions


Yes, you can over-neutralize.  Over-neutralize the pickle hide and your pH will be too high for the tanning agents to properly affix to the collagen.


Over-neutralize the tanned hide and you can very well break many of those crosslink bonds that the tan created.  It can cause hair loss, epidermis loss and easily torn hides...

The good news for us home tanners is sodium bicarbonate, aka baking soda, creates a very nice buffered neutralizing system.  It's not going to go much above a pH or 8 or 9 no matter how much you add.

The acid in a hide is not instantly neutralized.  The time it takes is dependant upon the type and thickness of the hide.  Rabbit theoretically should neutralize more quickly than a deer unless you have your deer as thin as that rabbit.

You folks that haven't tried it yet have really got to get your gloved hands in that neutralizing bath and squeeze the hide...

Feel the bubbles... ;)
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Baking soda is sodium bicarbonate. They are one and the same...

Re-hydrate! It is an important step.


Spell chek.....not jest enother perty button.
paul e
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« Reply #28 on: December 29, 2009, 08:35:04 AM »

great post guys
now i know why every now and then
you get a different feeling skin
great food for thought

most of us are scared to over do the baking  soda

your saying not to go crazy with it but using more will probably help if you monitor the pH of the solution in the skin while neutralizing
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using stop-rot up front makes everything else go better
and somewhere off in the distance a deer grunted
Monte
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« Reply #29 on: December 29, 2009, 09:36:33 PM »

Question, how do you all keep from precipatating out the tanning agent when you neautralize the pickle to a pH above the precipatation point of the tanning agent?
For example; alum   4.1
                  syntan 4 to 5
                  lutan F 4.1
                  lutan cr  4 to 5
                  liqua-tan 4 to 5


Just curious.
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