The measurement of surface roughness is not as straight forward as most other engineering measurements, such as length or angle or hardness; and in order to get good accuracy, expensive instruments are needed. These are often unsuitable for workshop use, where roughness of machined surfaces can usually be assessed conveniently and with sufficient reliability using visual and tactile (fingernail) comparison with a standard set of surfaces machined in the same way.

These problems are solved by this range of Roughness Comparison Specimens. They are simple to use, inexpensive, and therefore widely used in many different applications.

• checking roughness of turned, milled, ground, reamed, polished or lapped parts during machining
  
• checking the roughness of spark-eroded surfaces as described in the VDI 3400 Guideline
  
• checking the roughness of steel surfaces which have been prepared for painting by blast-cleaning, as outlined in ISO 8503
  
• estimating surface roughness prior to accurate measurement by a stylus instrument, as recommended
  in BS EN ISO 4288, eg.
  
• checking the seriousness of damage to parts caused by nicks, dents and scratches
  
• checking reconditioned ship propeller blades