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.

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...

I would never have thought to test the vinegar on it`s own
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

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.

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.

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.

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