Meisterprüfung Buchbinder Practice Questions - Meisterprüfung Buchbinder (Austria) Exam

The moisture test (Benetzungsprobe / Feuchtprobe): applying water to one side of a square test piece causes it to curl into a cylinder whose axis is parallel to the fiber grain direction. The flame test: burning a corner produces white ash along the grain and black ash across the grain. The pH spot test: chlorophenol red turns purple along the fiber axis and yellow across it. The thickness caliper test: measuring caliper across four corners, as paper is 30% thicker along the machine direction.