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Over Neutralizing,,, is there such a thing?

Discussion in 'Tanning' started by toaster, Dec 14, 2008.

  1. toaster

    toaster New Member

    I read this in a thread in deer heads, that you could over neutralize a cape or hide and wondered if this was true, or is it a myth like we still need to eat fish on Friday.
    Anyone done an actual test in the lab to prove this theory?
  2. orion

    orion Marty Silva

    I am by no means an expert at tanning but I think one of the ways they make a hair off leather is by giving it a bath in lye which is just the opposite of an acid hence the over neutralization.


  3. cyclone

    cyclone Posts: 400001

    Not a theory, it is fact...Soak a hide in base too long and you end up with a pile of goo...
  4. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

    It ain't no wonder why the illegals don't want to learn the English language. I heard, and understood you loud and clear, Treetops. You're an American, aren't you? Always remember, you live in a country full of hot water heaters.


    neu·tral·ized, neu·tral·iz·ing, neu·tral·iz·es
    1. To make neutral.
    2. To counterbalance or counteract the effect of; render ineffective.
    3. To declare neutral and therefore inviolable during a war.
    4. Chemistry
    a. To make (a solution) neutral.
    b. To cause (an acid or base) to undergo neutralization.
    5. Medicine To counteract the effect of (a drug or toxin).
    6. Slang To remove as a threat, especially by killing.

    neutralize or -ise
    [-izing, -ized] or -ising, -ised
    1. to make electrically or chemically neutral
    2. to make ineffective by counteracting
    3. to make (a country) neutral by international agreement: the great powers neutralized Belgium in the 19th century
    -isation n

    To cause an acidic solution to become neutral by adding a base to it or to cause a basic solution to become neutral by adding an acid to it. Salt and water are usually formed in the process.

    tr.v. ba·si·fied, ba·si·fy·ing, ba·si·fies Chemistry
    1. To convert into a base.
    2. To make alkaline.

    Verb 1. basify - turn basic and less acidic; "the solution alkalized"
    caus·tic Pronunciation: \ˈkȯs-tik\ Function: adjective Etymology: Latin causticus, from Greek kaustikos, from kaiein to burn Date: 14th century
    1 : capable of destroying or eating away by chemical action : corrosive
  5. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

    Baking soda (sodium bicarbonate), and sodium carbonate are in the carbonate form. Either one can be converted to sodium hydroxide by heating in water to temperatures over 140 degrees.

    Let's just say we are going to neutralize hydrochloric acid. What we are going to do is turn the hydrochloric acid into it's salt form. We add sodium bicarbonate to the hydrochloric acid and it reacts to form sodium chloride as it's end product. The balance of the carbon, oxygen, and hydrogen are given up as carbon dioxide and water.

    What would be produced by adding hydrochloric acid to sodium hydroxide?
  6. Monte

    Monte Missouri fur-Limited hair-tanning

    Hair removal in the leather industry is done in most part with hydrate lime and sodium sulphide. The wet drum run time is aprox. 1.5 hr. on deer and 2 hr. on cow or buffalo.

    Note; I still do not agree with neutralizing a pickle before the tan goes in. Neut. the pickle is sure to over neut. some sections of the skin rendering the tan useless.
    While some achieve results they are happy with by neut. the pickle it is not a sound practice.
    If the pH of the skin is above the precipatation point of the tan , How can this work unless a suitable buffer is used and I have not seen any home tans selling a buffer with their kits or products.
  7. Monte

    Monte Missouri fur-Limited hair-tanning

    Hudson ,The short answer is While leaving the skins in the pickle , hair-on or leather ,after determining that the pH in the pickle is what I want checked on the thickness of the skin , then the tanning agent and the buffering agaent is disolved and fed into the drum, paddle , or static vat while stirring, this can take from 3-24 hours depending on the tan agent used. I use the buffer agent to get a greater degree of tan by raising the precipatation point of the tanning agent while not giving up stretch. Regardless of the tan agent used , the tan agent and the buffer agent are fed into the pickle and slowly raised to the finished pH. All the time I have now, more later.
  8. Monte

    Monte Missouri fur-Limited hair-tanning

    oldshaver, I agree,I would never use soda ash, pH is not predictable and to difficult to maintain consistency. I don't think it would make a reliable buffer.
  9. toaster

    toaster New Member

    Soooooo,, one tablespoon of baking soda per gallon of water,,,, who came up with that rule of thumb as the standard for neutralizing a home tan, and what would two tablespoons of baking soda per gallon do? Wouldn't that be considered over neutralizing?
  10. Glen Conley

    Glen Conley KARMA GOOSE R.I.P. 2006-2006

    I can't remember the kid's name. It was Joe, or Johnny, or Billy, or something.

    Here's a short article you might find useful.

  11. cyclone

    cyclone Posts: 400001

    You could put a truckload of bicarb in the solution and it wouldn't hurt the hide IF(notice the if) you monitor the pH within the hide. When it gets to the desired pH...Pull and rinse..

    When you put sodium bicarbonate or sodium carbonate in solution, the carbonate or bicarbonate ion have the ability to pull a proton (H+), hydrogen ion or the ion that causes acidity off of a water molecule.

    H-O-H(water) ------> OH-(hydroxide)...The hydroxide is formed.. (no the equation isn't balanced)

    Soda ash, sodium carbonate is a salt. It can pull two hydrogen ions of of two water molecules forming two base or hydroxide units.

    Sodium bicarbonate, baking soda, can pull one hydrogen ion off of a water molecule...It can also donate one hydrogen...

    Baking soda is an acid salt. It has a hydrogen ion that it can donate as well...It can act as a base. It can act as an acid...It makes a most versatile buffer solution..

    Now with all that being said, doubling the amount of baking soda isn't going to hurt a thing if you monitor the pH properly....

    (You did notice the if...) right?
  12. Monte

    Monte Missouri fur-Limited hair-tanning

    cyclone, your big IF is most important. I don't think it is likely that the adverage home tanner has the skills to monitor the pH through the thickness of the skin. The brisket and the skin on the back of the neck are of great difference. The risk of damaging the thinner parts of the skin is evident by a lot of folks on here explanning the hair loss on the lower end of the cape where it is thinner.
    It is much safer to neutralize after the tan has penatrated the skin thickness in the thicker areas and over a longer period of time than to neutralize the pickle. How can you fix the tanning agent any other way without guessing. My tanning experience on hair-on and leather spans over 40 years and I have made every mistake you can imagine.
    The fixation point of all the different tans is a different pH.
    Aluminum sulphate--4.2, buffered 5.2 anything higher will ruin the tan. Note; the carbonates will not work for buffering the alum tans.
    syntans- vary from 4-5.5 and never really stop tanning in this range ( they were invented to replace veg. tans when bark was hard to get from abroad in the early 1900's.
    Chrome 4.2 to 6.8
    This covers most of whats availabe to taxidermist. Aldahydes and veg. tans are not significant to the home tanner. enzyme (brain) is almost entirly a home process.
    Oil or chamios tanning is hard to control and of no sigifance to the home tanner. When properly done makes the best hair-on skin you will have your hands on and cost more to do.
    The info I have provided is just food for thought.
  13. cyclone

    cyclone Posts: 400001

    Much like me, he is a bucket tanner Monte. The one tablespoon recipe had to come from the marketer of a home kit trying to put steadfast directions on the process.

    Would 1 Tlbs/gallon work on a bison hide, elk or moose hide? How about a mouse?

    I'm sure that tanneries use recipes for large batches that ensure success. I'm sure that you wouldn't consider the pH "adjusted" immediately after just adding X amount of base...It takes time to react with the acid in the solution as well as the acid within the hide itself. It is not instantaneous.

    Deja Vu...didn't we have this discussion before? http://www.taxidermy.net/forum/index.php/topic,26754.0.html
  14. Monte

    Monte Missouri fur-Limited hair-tanning

    I am sure we did. The questions keep on comming. However , I do enjoy discussing tanning . Any kind
    Also I work off percentages of hide weight.
  15. toaster

    toaster New Member

    Sooooooo,,, Monte,,, You paid your dues and learned your lessons, why would vendors to home tans recommend to neutralize before tanning? And you firmly believe in neutralizing a tanned skin, what would it take for your theory to become the industry standard vs. the current paradigm?

    Glen,, I heard that preach'n before, was baptized in soft water of neutrail pH.
  16. Monte

    Monte Missouri fur-Limited hair-tanning

    Treetops,If I were to become a vender of the same products that are available through the taxidermy supply houses , I would change the instructions .
    Neutralizing a pickle is just ass backwards. I have tested and tanned with most of the products availabe. Every thing that is available is a compound mixture from some hugh ,world wide chemical company. Most of these products were supplied to me free for evaluation between 25 and 35 years ago. There are only so many tanning agents available. I no longer tan commercial. I have a medium size taxidermy studio of over 5000 sq ft. We still do some in house tanning and send most of it out. All in house tanning is sulphuric acid pickle or alum pickle followed by liqua-tan. This produces the highest quality in house tan in my opinion.

    Just like taxiedermy, tanning will never have an industry standard.
  17. Bones88

    Bones88 Duthill Tanners

    I am your simple home tanner and I have never checked the PH on any of the 7 hides I have done over the last 9 years, I am only your hobby tanner, from what I am reading I may just be lucky but I haven't had a hair problem with any of them.

    I salt it
    I flesh it
    I salt it again
    I use water & vinegar pickle 2:1 ratio
    24 hrs later rinsed well
    Neutralize with 1 cup baking soda to 5 gallons water 20 mins
    Rinse and mix Lutan F to tan
    I go by the book, deer 13-15 hrs etc
    Rinse, dry and stretch

    This is a great hobby, good work for all that make a living this way.

  18. bill@hogheaven

    bill@hogheaven New Member

    Treetops there is a second part to your rule of thumb....20-30 minutes in the solution.