Checked your vinegar pH lately? An interesting observation...

[mdtraveler]

Most of the extraction procedures on the Nexus call for a very dilute vinegar solution for acidifying bark. That didn't seem quite right to me, and thus HCL was used for some previous extraction attempts. Today I decided to test regular food grade vinegar available in grocery stores everywhere, and confirmed what I had suspected. A pH of between 2 and 4 is what most procedures call for, and this is apparently supposed to be achievable by diluting regular vinegar. Well, out of the 3 brands of very commonly available vinegar that I tested, 2 of them had a pH of greater than 4, and one had a pH of over 5 - all undiluted, right out of the bottle. So, I guess the moral of this story is that it would b a good idea to test your vinegar before diluting it, because it may not need to be diluted at all.

 

[TGO]

Vinegar comes diluted right out of the bottle usually. What acidity percentage were you using? I always use vinegar that is diluted with water to 5% acidity.

I just did an experiment:

I took 450ml of tap water and threw one shot (approx 50ml) of 5% vinegar into it and stirred. Then I took litmus paper and tested the water which turned orange signifying that a pH 2-3 was reached. I repeated the experiment three times with the same result. I will attach a pic in a moment.

I am curious as to why your vinegar is acting strange...

 

[concombres]

Most of the extraction procedures on the Nexus call for a very dilute vinegar solution for acidifying bark. That didn't seem quite right to me, and thus HCL was used for some previous extraction attempts. Today I decided to test regular food grade vinegar available in grocery stores everywhere, and confirmed what I had suspected. A pH of between 2 and 4 is what most procedures call for, and this is apparently supposed to be achievable by diluting regular vinegar. Well, out of the 3 brands of very commonly available vinegar that I tested, 2 of them had a pH of greater than 4, and one had a pH of over 5 - all undiluted, right out of the bottle. So, I guess the moral of this story is that it would b a good idea to test your vinegar before diluting it, because it may not need to be diluted at all.

I would never have thought to test the vinegar on it`s own :lol:
Generally i use a PH meter to test the PH of the solution once the bark & acid has been added & shoot for PH 4.

I think i should mention as well, you need to be EXTRA careful working with HCL. Do not use any metal pots, stirring instruments, etc. If you are using HCL.
I have seen on several occasions posts here about others running into trouble using HCL during extraction as well & I also believe HCL will evaporate during a boil & the vapors can be hazardous to breathe in.

Don`t mean to lecture you on using HCL. For all I know you know all that already & are fully capable of safely using HCL in an extraction. Better to be safe than sorry when it comes to potentially hazardous chemicals though

 

[mdtraveler]

Vinegar comes diluted right out of the bottle usually. What acidity percentage were you using? I always use vinegar that is diluted with water to 5% acidity.

I just did an experiment:

I took 450ml of tap water and threw one shot (approx 50ml) of 5% vinegar into it and stirred. Then I took litmus paper and tested the water which turned orange signifying that a pH 2-3 was reached. I repeated the experiment three times with the same result. I will attach a pic in a moment.

I am curious as to why your vinegar is acting strange...

And I'm curious as well. This isn't the first time I've had this issue. A couple of years ago, I was working on something unrelated that required a minimum of 5% acetic acid to be used. I had to freeze distill 3 gallons of vinegar to combine with a 4th gallon to be able to keep it over the minimum 5%. I've no idea why this is the case, but it seems that something is either degrading the vinegar, or what is available locally is significantly less than 4% to begin with. I didn't think to take pictures when I did my tests, I'll do it again when I get time and post pics.
Also, I have a strong hunch that if you check the pH of plain distilled water after adding it to the bark, that it will be well below 7 without adding any other acid. My point is that just because the pH is 4 doesn't mean that the stoichiometry is correct to convert the majority of the tannins to acetates. That's basically what I was getting at.

 

[mdtraveler]

And good points about HCL and its safe use. It's good to mention for the benefit of others even if you already know I have experience with it, and utilize the proper procedures, PPE etc.

 

[TGO]

Vinegar comes diluted right out of the bottle usually. What acidity percentage were you using? I always use vinegar that is diluted with water to 5% acidity.

I just did an experiment:

I took 450ml of tap water and threw one shot (approx 50ml) of 5% vinegar into it and stirred. Then I took litmus paper and tested the water which turned orange signifying that a pH 2-3 was reached. I repeated the experiment three times with the same result. I will attach a pic in a moment.

I am curious as to why your vinegar is acting strange...

And I'm curious as well. This isn't the first time I've had this issue. A couple of years ago, I was working on something unrelated that required a minimum of 5% acetic acid to be used. I had to freeze distill 3 gallons of vinegar to combine with a 4th gallon to be able to keep it over the minimum 5%. I've no idea why this is the case, but it seems that something is either degrading the vinegar, or what is available locally is significantly less than 4% to begin with. I didn't think to take pictures when I did my tests, I'll do it again when I get time and post pics.
Also, I have a strong hunch that if you check the pH of plain distilled water after adding it to the bark, that it will be well below 7 without adding any other acid. My point is that just because the pH is 4 doesn't mean that the stoichiometry is correct to convert the majority of the tannins to acetates. That's basically what I was getting at.

Yes, I agree which is why I generally add a bit more vinegar than necessary, just to be on the safe side. It seems to work well and have had 1%+ yields on ACRB (crystals/wax).

This is very strange and I hope you are able to figure it out what is happening.

 

[downwardsfromzero]

I had to freeze distill 3 gallons of vinegar

That's not distillation!

/hands in entry to 'Pedant of the Year' contest

Jeez, bunk vinegar now - whatever next?

 

[mdtraveler]

I had to freeze distill 3 gallons of vinegar

That's not distillation!

/hands in entry to 'Pedant of the Year' contest

Jeez, bunk vinegar now - whatever next?

I'm guessing it's a QC issue, because none of the vinegar I tested was anywhere near 5%.

At the risk of ruining your chances of winning the P.O.Y. award, I would just like to say that fractional freezing is technically a distillation. There are also vacuum freeze distillations used in the nuclear power industry. That would be interesting to see.

**Edit: Forgot the citation. Determination of Tritium Concentration in Fuel Reprocessing Liquid Waste by Vacuum Freeze Distillation