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Rinntech Resistograph
Rinntech Resistograph for wood density analysis

Resistograph is an electronic high-resolution needle drill resistance measurement device, developed by Frank Rinn (since 1986 in Heidelberg, Germany).

A thin, long needle is driven into the wood. The electric power consumption of the drilling device is measured, recorded and printed. Resistograph devices are different from other resistance drills because they provide a high linear correlation between the measured values and the density of the penetrated wood. They are used for inspecting trees and timber in order to find internal defects, and to determine wood density and growth rates.[citation needed]

External links[edit]

  • [1]: History of the Resistograph and IML trademark violations, as well as basics and application of needle resistance drilling, including literature references.
  • [2] : Rinntech home page
  • [3]: Resistograph - device details and description


  • Rinn F. (1988): Eine neue Methode zur Bestimmung von Jahrringparametern. Physik-Diplomarbeit, 85 Seiten, Universität Heidelberg.
  • Rinn, F. (1989): Eine neue Bohrmethode zur Holzuntersuchung. Holz-Zentralblatt 115, (34): S. 529-530.
  • Rinn, F. (1990): Vorrichtung zur Materialprüfung, insbesondere Holzprüfung durch Bohr- bzw. Eindringwiderstandsmessung. Patent DE4122494B4, Prioritätsdatum 3. September 1990.
  • Rinn, F., Becker, B., Kromer, B. 1990: Density Profiles of Conifers and Deciduous Trees. Report of the Symposium on Tree Rings and Environment of Lund University, Ystad, South Sweden, September 1990.
  • Eckstein, D. und U. Saß: Holzanatomische Untersuchungen zu Bohrwiderstandsmessungen an Laubhölzern Holz als Roh- und Werkstoff, (1994) Holzforschung 52, S. 279-286
  • Rinn, F, Schweingruber, F.H., Schär, E., (1996): RESISTOGRAPH and X-ray density charts of wood comparative evaluation of drill resistance profiles and X-ray density charts of different wood species. Holzforschung 50: (4), 303-311.