I occasionally run across a new brand of watercolor or mixed media where the listing says it's acid-free, but the pad doesn't say anything about it. I wondered if there was a way to test the paper that didn't involve grinding it up and putting it in Ph neutral water, and in my searches, someone on a forum recommended this, theLineco pH Testing Pen for Paper or Paperboard Products.. I ordered one immediately.When I opened it up, there was a label firmly stuck over the part that tells what color to look for, so I came back to the listing and noticed a reviewer said this was just a purple marker. So I did a test.I used the marker on 3 pads of watercolor paper. All three showed a purple mark, which is the sign the paper is Ph neutral. Then I took one of those sheets of paper and gently applied lemon juice across the surface. When it dried, I tried the maker on it - and got a clear line, which means the paper is "unsuitable" or acidic.So yes, this pen does work. It works if you want to test your paper for Ph to make sure it won't yellow, become brittle or cause ink, watercolors or pencil to fade over time. Good news for me is that the very nice paper I got recently that didn't say it was acid-free on the pad got a purple mark from the test pen. One of the older pads that claimed in the listing to be acid-free but not on the pad ended up with a clear mark. Super product.

Tester l'acidité des feuilles de scrapbooking

Works as described. LineCo is reputable manufacturer.

12 quid for a pen - pfff. but it does the job

Excelente