Acid-Free Foamboard is used as a mounting surface by photographers and artists who are concerned about preserving their work. Unlike regular foam board whose surface has a pH rating of 6.5, this archival sheet has a pH rating in the 7.3 to 8.5 range. Each board has been buffered with an alkaline substance to maintain the pH level for years.
Antique white sheets are 32" x 40" and 3/16" thick.
