Originally Posted by ghostrider

There are inexpensive pH testers that artists (and scrapbookers, I believe) use to test papers and matboards (first got mine for printmaking).

It's like a felt tip pen. The mark changes color to indicate the acid level with a high, moderate, or acid-free rating (can't find my 'score card' at the moment). I've also tried it on corrugated cardboard to confirm it works and that tests high.

Dick Blick is one source, but I'm sure there must be more...maybe even Michael's.
http://www.dickblick.com/products/ac...kTracking=true