pH Testing Pen
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With this pH testing pen it is easy to determine if a paper or board is acidic. A simple method to distinguish between a safe (neutral or alkaline) and an acid material. Easy to use, simply draw a small line on the material you wish to test. The chlorophenol red indicator solution in the pen will turn purple on any paper with a pH of 6.8 and above. A clear or yellow color indicates the material is probably unsuitable for conservation purposes.
Note: Unreliable results may occur on colored or coated papers.