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A discussion of PH

Discussion in 'Tanning' started by Rhino, Dec 22, 2009.

  1. Rhino

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

    Some of the posts on here concerning PH, that I have been reading, I am finding a little disturbing, to say the least. :eek:

    Please take a few minutes, to read and study this link, before posting.(include formic acid, in the 2 area)

    http://staff.jccc.net/pdecell/chemistry/phscale.html

    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?

    Do you folks that like to have a pickle at a PH of 1, or 1.5, REALLY think you are neutralising a skin, with 1oz of baking soda per gallon of water, for 20-30 minutes? Heck no, YOU ARE NOT, and I don't care what your PH paper reads after placing it on the skin!

    Your PH, needs to remain between 2, and 2.5, and that's it! A PH as low as 1 or 1.5, is EXTRTEMELY hard to neutralise! You are wasting acid, and I very rarely see mention of adding more salt, when adding more acid, to adjust the PH, to these ridiculously low PH values?

    Salt, is your ONLY defense, against the acid eating up your skins! The salt content in your pickle, IS NOT a constant. 25% of it, is being absorbed by the skins, SO, every time you add acid, YOU ADD SALT.

    OK, lets talk.
     
  2. Monte

    Monte Missouri fur-Limited hair-tanning

    oldshaver, I agree 100%. pH below 2 does not do anything to assist the pickle or the tan.
     

  3. livingtrophytaxidermy

    livingtrophytaxidermy New Member

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    i didnt know any of this.never have had one problem since ive tanned my own skins keeping it close to a ph of one.what about if you neutralize the skins for 3 to 4 hours.the tan i use calls for a ph no higher than a ph of 1.5 and neutralizing for 3 to 4 hours.should i be concerned about the instructions on these containers?
     
  4. cyclone

    cyclone Posts: 400001


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

    George The older I get, the better I was.

    Guess it comes from the upbringing, but I've always been a believer in the 1.0 to 1.5 as well. Always had a super saturation of salt in the water and always used at least a pound of baking soda to neutralize (ONE TABLESPOON AT A TIME while monitoring the pH) Just felt like I got a better job on the "iffy" hides that way.
     
  6. craigjw

    craigjw http://www.back2lifetaxidermy.com

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    Old shaver, I like my ph at about 2, however, I like to have it at 1.5 until it levels out. If I start it at 1.5, When I wake up in the morning it will be at 2.5, I bring it back to 1.5, go to work, come back and it is at 2.5. bring it back to 2 and it stays there. Do you feel it is acceptable to have it at 1.5 for this reason? Its probably not there for more than a couple hours, and I have never had a problem doing it this way.

    Was not aware that it is a good Idea to add salt when adding acid. How much would you add to an 8 gallon pickle? Can you have too much salt?
     
  7. Rhino

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

    Cyclone, PLEASE school us! I would love nothing more, than to have you and possibly Glen, jump in this thread! I'm all ears, well, actually, belly! :eek:

    Livingtrophy, its not so much that I am saying anybody is wrong. What I am suggesting, is that a PH below 2, is overkill, in my opinion. I am also thinking out loud, and suggesting that the "lock step" directions everyone gives for neutralising, NEED to be modified, to fit the individual pickle, according to its PH. This is where Cyclone could help us!

    Livingtrophy, what EXACTLY do you put in your neutralising bath, and your pickle?

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

    What I want to discuss here, is that depending on your pickles PH, should one set neutralising formula, and neutralising time, fit EVERY set of circumstances?
     
  8. cyclone

    cyclone Posts: 400001


    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.... ;)
     
  9. livingtrophytaxidermy

    livingtrophytaxidermy New Member

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    1 pound of salt per gallon half ounce of safety acid per gallon and it puts it at one pretty much.ive never had it go above 2.its at 1.5 now.and it rises for a couple of day or until i do a rough shave and put the skins back in.before the 2nd shave it pretty much stays where its at.neutralize 1 ounce of baking soda per gallon 3 to 4 hours
     
  10. cyclone

    cyclone Posts: 400001

    Absolutely not..

    George likes his pickle "hot" as he calls it, a pH of 1.5 or lower. He is using more acid. There is a higher concentration of acidic ions in the solution thus there is a higher concentration in the hide once pickled. He needs a higher concentration of bicarb to bring his cape to the desired pH than does someone who is keeping their pickle at a pH of 2.

    Now here is where it's going to get complicated. Depending on what acid is being used is going to have a bearing on how much bicarb needs to be used. One that uses hydrochloric acid or another monoprotic strong acid is going to use less bicarb than if they used the same concentration of citric acid. Notice I said concentrations, not pH... Some acids like sulfuric, citric and oxalic have more than one acidic proton to donate to the solution so naturally they will need more bicarb to neutralize.

    Other weak acids such as formic and acetic do not fully donate all of their acidic protons to the solution. It takes more acid to get the pH lower because they don't like to give up their acidic proton. As these acids are neutralized and the pH raises, more of the acidic protons will be released from the acid...

    I just went back and read this and I realize how confusing this all is...

    To be honest, I dump as much bicarb in my neutralizing solutions as I want. I agitate the hide and check the pH of the skin itself after 15 minutes. I have neutralized as long as an hour and as low as 10min for a deer sized cape. The important factor to me is to get the pH of the hide ready for the tanning agent, not the pH of the final solution..

    I know that this is much different for tanneries OS...

    Your turn..
     
  11. livingtrophytaxidermy

    livingtrophytaxidermy New Member

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    just the other night i was neutralizing 2 capes in the tanning bath and forgot to pull them out.it was a hectic day.so the next morning i realized that they were still in there.everything was fine.but i was wondering what could of happened.
     
  12. Bobbi Meyer

    Bobbi Meyer I luv to ride my tricycle, I luv to ride my trike

    so what is the best method for taking the ph of the hide. just wipe the hide pretty dry then lay your ph strip on it?
    I've always just checked the solution...sounds like I need to adjust my methods.
    This is all very interesting and informative.
     
  13. cyclone

    cyclone Posts: 400001

    I rinse the neutralizing solution off of a thick piece of the hide, pat that area dry and then squeeze some of the liquid out of the hide at that spot. Touch the pH strip to that liquid..


    Another thing that I do is agitate the hide by hand. Squeeze the hide in the neutralizing solution. If you are using bicarb, you'll feel tiny bubbles (not the Don Ho type) in the hide. The bicarb is still working.

    For those like me that use a "paint on" tan after, I need only to get the hide close to a pH or 5 or 6. The liqua Tan will re-adjust it to where it needs to be..

    If the hide is neutralized correctly it will suck up the Liqua Tan like a sponge. If not, it will puddle on the hide and take quite a while to soak in...


    It is also important to rinse the neutralizing solution off of the hide and out of the hair with clean water after the pH is adjusted properly. Otherwise your pH is still changing...
     
  14. Bobbi Meyer

    Bobbi Meyer I luv to ride my tricycle, I luv to ride my trike

    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.
     
  15. RTF

    RTF Active Member

    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.
     
  16. Jon S

    Jon S Active Member

    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).
     
  17. RTF

    RTF Active Member

    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.
     
  18. cyclone

    cyclone Posts: 400001

    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.



    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...
     
  19. Jon S

    Jon S Active Member

    Nope, everything I have ever read about neutralizing has always been based on time, along with the dangers of neutralizing too long.
     
  20. livingtrophytaxidermy

    livingtrophytaxidermy New Member

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    what wiil happen if you neutralize too long? i guess hair loss???????