Re: Eliminating CaCO3 in buffer in "achival" watercolor papers
Acids in general tend to deteriorate paper. However, as a practical matter, I can say that I have used the aforementioned HCl treatment for the better part of 40 years on scores of different papers, and have almost never had a problem (of course, none of my prints is over 200 years old yet, so I cannot say definitively that there will not be adverse effects that show up over a term of centuries, but none of the readily observable characteristics of the papers has been affected over a term of decades). Note that I am scrupulous regarding washing, and have tested my washing procedures thoroughly.You're right, my (maybe wrong) point was that: since acetic acid is a milder acid compared to HCl, it would do less harm to the paper, acutely... As far as I can read, acetic acid is the main cause of paper deterioration, so it has to be thoroughly washed out of paper when done.
The "almost" refers to one or two papers where the sizing reacted poorly to the HCl bath. This was apparent immediately -- not a latent damage issue.