About Harboro Rubber Engineering in Rubber      Contents      Introduction      Uses of Rubber      Processing Rubber      Designing With Rubber      Selecting / Specifying Rubber      Quality In Rubber          Quality          Zero Defects          Hardness          Dimensions          Forces (keypads)      Rubber Directory      Health & Safety      Measuring Properties      Glossary of Terms      Request A Copy Contact Information

Hardness   Hardness is measured by pressing an indentor into the rubber and measuring penetration. Shore A is based on an immediate reading using a spring applied load. Variation from user to user can be as great as +/-2.5°. IRHD uses a dead load with a 30 second wait and is more consistent, giving user variations of +/-1.5° (3 sigma). There can be significant differences between the two types of readings.