Having used some intersesting “found” paper for a print collage which turned out to be something I really like, I started worrying about the quality of these large sheets of colored paper. After a little Internet research, I bought a Lineco Ph testing pen, and tests on scrap seem to indicate the paper is acidic.
Mind you, all these ph test pens get some rather mixed reviews, and test reports recommend that you test the pen first yourself, and develop your own color scale since manufacturers information is not reliable! Still a few tests on paper advertised as acid-free produced a light lavender consistent with the pen instructions, while tests on tissue paper and newsprint were clear, indicating high acid content.
So then what to do with my acidic artwork? I settled for buying a can of Krylon “Make It Acid-Free!”. A couple of test sprays did not alter the paper color or the ink colors. And my Lineco pen seemed to indicate lowered acidity, so I sprayed the work. Then I was in for a day of panic: several pinky brown patches, some quite large, scarred my work! Horror, and I gave it up as ruined when they remained after a few hours of drying time. Probably the spray was reacting to previously invisible oils, glues, or other material.
Next morning, surprise! The splotches had faded completely. The piece looks as before.
However on further testing of scraps, reapplication of spray, etc. I doubt the value of the spray. The purple writing of the test pen on the sprayed paper fades to almost clear very quickly (a few minutes), and a clear result indicates high acidity. The spray is probably a very thin porous coating of low acid material that does not really penetrate the paper. After three light coats of spray a whitish coat is starting to show on my colored paper.
So hard to know if I am wasting my time (and money). I would love this artwork to be a little longer lived & light resilient, but what to think? What to do!!??