I have a case of Bic “Mark-It” permanent markers on my desk next to me. They’re great stuff; you can get a nice watercolor effect from them if you do it right. I’ve always bought them individually, but it turns out the pack has extra colors.
ANYWAY… there’s the standard checklist on the back about how awesome the product is. Bold colors, long-lasting, marks everything, etc. And the ink is acid-free. More than acid-free, in fact. It says, and I quote, “No added acid, no measurable pH.”
Okay, I understand what they’re trying to say, but we do have a pH number for true neutral. 7, if I remember my chemistry correctly. Apparently these are (excuse the pun) magic markers, laughing in the face of science and defying all attempts at quantification.
It’s not correct to say something has “no pH” to mean non-acidic. No pH is something more like non-ionic, like gasoline.
Picky point:
Solvents other than water will dissolve organic acids. It helps a lot if the solvent is polar (having electrical charge separation inside the molecule). The acid’s ability to ionize is limited in these sorts of solvents, but still has a measurable effect. Normal phase chromatography depends on it. Then there are other interesting things like aprotic solvents, and liquid salts.