That ph chart in old bookbinding manuals is misleading

I was looking up pH neutral adhesives for a restoration project and found out that most old bookbinding manuals reference a pH scale that's off by about 0.5 points. The Library of Congress put out a paper back in 2021 showing how common test strips can read differently depending on the paper's buffering. Has anyone else run into this with their own supplies?

3 comments

3 Comments

hannahk1923d ago

Read an interesting post on r/bookbinding about this a few months back. Someone tested old manuals against modern ph strips and found the same 0.5 point difference you're talking about. The buffering thing is real too, I've had test strips give me totally different readings on the same paper just because I tested a different spot. Makes you wonder how many old books got messed up by people following those charts.

fiona_young23d ago

Has anyone actually looked at what kind of water they were using for those ph strips back then? Tap water pH varies wildly depending on where you live, and if the manual just said "wet the strip with water" without specifying distilled, you're getting a reading from the water too, not the paper.

annas876d ago

Oh wow, that's a really good point about the water. Did those old manuals ever even mention distilled water, or was that just assumed?