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Discussion in 'Tanning' started by q tip, Dec 16, 2010.
when i neutralize what do i use and what ph level do i want thanks
check the archives, its been well covered.
There is a lot in the archives, but it depends on what you're neutralizing and for what process, got any details?
The better and most used product for neutralising ( or give PH Up) of the acid pickle is Sodium Bicarbonate ( Baking soda ) 8)
And remember, it is a small p and large H. Cyclone will set you straight if you don't do it right.
I know that I can count on you when I'm outta town..
(actually it's lower case and upper case...)
"Basification and Neutralizing: Drain skins from pickle and place them in clear water. Immediately add a small amount (approx. 1 oz per gallon) sodium bicarbonate or other neutralizing agent until a pH of 4.5-5.0 is reached. Leave the skins in solution for 30 minutes and then drain well and rinse."
I will add (you never see this in any directions), that the pH when neutralizing should be measured by touching your paper to the skin to get the most accurate 4.5-5.0 and not the pH of the water, which will probably be irrelevantly a little higher.
Joe, you can check a skins pH, but what you are talking about is an old wives tale.
You have to let a skin completely dry, then re-wet a small area with distilled water, wait a few minutes, THEN you can check the skins pH with litmus paper.
OS, you are talking about what "can" be done, but if my method is wrong, please tell me what "should" be done to ensure the skin is at the right pH to properly "accept" the tan? My thinking is the skin "needs" to be at a pH of 4.5-5.0 to properly accept the tanning agent. No?
I'm confused. I thought the main purpose of neutralizing was to raise the pH of only the outermost layer of skin so the tan will penetrate and go into the deeper (slightly more acidic) layers? If that's the case, how do you get an accurate pH reading? ???
Raising the pH is done to "fix" the tan to the fibers, after it has fully penetrated and bonded to the fibers. What Joe is telling you will work fine for what you are doing.
I will put this in plain English.
First off, that clip Joe posted, came from the LIQUI-TAN instructions page.
Second, touching pH paper to the surface of the skin, DONT WORK, so dont waste your time.
That is just some anal retentive crap that some laymen came up with.
When neutralising before applying a PAINT-ON TAN, leave your pH papers in the closet, and just follow the directions, and dont worry about it.
Im NOT telling anybody to go buy some distilled water! ??? ??? Cant anyone read between the lines at all, around here?
os, you seem agitated?...sorry if so because I learn a lot from reading your posts, but please articulate to me HOW as you say it "DON"T WORK"....I mean if the water pH is at 5.0 and the skin is at 3.0 then I see a problem..no?
Leaving the pH papers in the closet wouldn't be following the directions.....
Slightly disagree OS..and Joe as well, slightly.
Rinse a portion of the hide (skin side, of course), pat dry. Squeeze a small amount of the liquid within the hide so that it comes to the surface and touch the paper to this fluid. It more accurately represents the pH within the hide for us bucket tanners. You don't have to be dead accurate with this method as most good paint on tans will adjust the final pH once absorbed..
..and I don't see the need to monitor the pH of the neutralizing solution that closely. The final pH of the hide, yes. The neutralizing solution, as long as it is above what you want your final pH, NO..
Bucket tanning only...using paint ons..
Cyclone, thanks. That's basically what I was saying. Ok, I said check the pH of the skin and yes skin probably doesn't have pH, but I was checking the fluid in the skin by, like you say, squeezing the skin to measure the pH of the wet skin, which is always lower than the water in the bucket.
That's my point. You want to get the pH of the skin fluid to 4.5 to better absorb the brush on tan, because when the bucket water is at 4.5 the skin fluid is still at 2-3 ph.
At any rate, this certainly isn't rocket science or even college chemistry...
I'd like for OS to add to this Joe. I certainly could be missing something..but to my understanding the paint on tans should further adjust the pH of the hide to fix the tanning agent. I just know that when I get the hide to a pH 4 or 5 the LT sucks into it almost as fast as I can spread it..
I agree. I've used Liquatan and my end product has been MUCH better after I started putting the pH strips to the skin rather than the neutralizing water. Knoblochs says the pH should be 4.5-5.0 to accept the tan. I'm confident they aren't talking about the neutralizing water being the 4.5-5.0 milestone.
This is a good discussion, OS please tell us your thoughts?
Ya Joe, I was a little irritated, but not by what you think.
I will explain to you why I think that checking the skins pH BEFORE drying it out an re-wetting it, is a waste of time. Im not telling anyone to do this, but I think this is the only TRUE way to measure a skins pH.
Here is a cut and paste from a well known Leather Chemist.(well known in his circle)
A large proportion of the water content of wet skin is present within the spaces around and between the fibres. Removal of this water during initial drying has little effect. The remainder, however, which is approximately one third of the (dry) weight of the collagen, is very closely associated with the collagen molecules which are said to be fully hydrated. The bound water forms a "sheath" around the protein chains and, in effect, keeps them separate from adjacent chains. This water is attracted to the protein by weak inter-molecular forces and as drying continues the protein structure collapses to the point where the same forces begin to act between adjacent collagen molecules, in effect, gluing them together. This force gives rise to a mechanism known as "hydrogen bonding" and is due to the fact that there is a subtle variation of charge along the protein chain with an attractive force between areas of opposing charge. These bonds are fairly easily broken by the re-introduction of water.
Again, this is just for having fun and conversation.
What I read out of the above paragraph, is, you need to dry out a skin, and re-wet it with a distilled water, to find out a skins correct pH. By drying it out, you leave ONLY water that is "closely formed" around the protein chains, that you can not see or feel. After re-wetting, THEN and only then, can you get a TRUE pH of the collagen, and NOT the liquid losely surrounding the fibers. Maybe yall are right, but this is just my opinion.
Tomorrow, I might start a new thread with some info on the differences between submersibles, and paint-on tans, and how they work MUCH DIFFERENTLY.