Surface roughness and smoothness can influence printing, coating, converting and other end-use performance. Different measurement techniques can be used depending on the material, application and surface characteristics that need to be evaluated.
Air leakage methods
Air leakage methods are widely used to assess the roughness or smoothness of paper and board. Smithers offers several recognised techniques.
Bendtsen roughness
Bendtsen testing measures the rate of airflow between the paper surface and a measuring head, providing an indication of surface roughness.
Testing is available to BS 4420, ISO 8791-2, DIN 53108 and SCAN P21. Smithers is UKAS ISO 17025 accredited for testing to BS 4420.
Bekk smoothness
Bekk testing assesses surface smoothness by measuring air leakage across the test surface under partial vacuum.
Applicable methods include ISO 5627, TAPPI T 479 and DIN 53107.
Parker Print-Surf roughness
Parker Print-Surf testing is specifically designed to assess the surface roughness of printing papers under conditions representative of the printing process.
Applicable methods include BS 6563, ISO 8791-4, TAPPI T 555 and SCAN P76.
Profilometry methods
Profilometry provides a more detailed characterisation of surface texture and can be used to investigate roughness, waviness and surface form.
Contact profilometry
Contact profilometry uses a stylus that moves across the material surface to measure variations in its profile. Testing can be carried out with reference to relevant standards including ISO 3274.
Non-contact profilometry
Non-contact profilometry enables detailed analysis of surface texture without physical contact with the sample.
Smithers can evaluate a range of two-dimensional surface parameters, including roughness average, peak-to-valley height, waviness, peak density and mean peak spacing.
The software supports a large number of two dimensional roughness parameters, detailed in the table below:
Roughness parameter | Description |
| (ISO) Ra | Roughness average |
| (DIN) Rz | Mean peak to valley height |
| (ISO) Rz | Ten point height |
| (ISO) Rmax | Maximum peak to valley |
| (ISO) Rm | Minimum valley depth |
| (ISO) Rq | Square root of average of the square deviation of the scan |
| (ISO) Wt | Waviness |
| (ISO) Nr | Normalised peak count |
| (ISO) S | Peak profile density |
| (ISO) D | Peak count |
| (ISO) Sm | Mean peak spacing |
| (ISO) R3z | Vertical mean form third highest peak to third lowest valley |
Talk to our experts about your paper or board material, application and the surface properties you need to evaluate.
