pH Testing Pen

St. Louis Art Supply Verified independent store

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Ever wonder if your paper is acid-free? For archival purposes, paper should have a pH above 6.8, preventing color changes and damage in long-term storage. This handy pen from Linec o helps you make sure: the mark stays purple on surfaces with pH greater than 6.8; it turns colorless or amber on surfaces with pH less than 6.8. Made in the United States. Show more