Substrate Inspector


Basis Weight or Grammage

The basis weight, substance or grammage is the weight per unit area. This can be expressed as the weight in grams per square meter (GSM or g/M2), pounds per 1000 sq. ft. or weight in Kgs or pounds per ream (500 sheets) of a specific size.


Bulk (density)

Bulk is a term used to indicate volume or thickness in relation to weight. 

It is the reciprocal of density (weight per unit volume). It is calculated from a thickness (caliper) and basis weight. Bulk (cubic centimeter/g) = Thickness [mm] * 1000 / Basis Weight [g/m2]. Sheet-bulk relates to many other sheet properties. Decrease in bulk or in other words increase in density makes the sheet smoother, less opaque, glossier, lower in strength etc.

more information:


Thickness (caliper)

The standard procedure for thickness measurement is explained in TAPPI T 411.

more information:



The standard procedure for glossiness of the paper measurement is explained in TAPPI 480.


Roughness and Smoothness

Currently, Substrate Library doesn't support roughness and smoothness. 
Those parameters will be added soon.

Basic measurement methods:

  • Air leakage methods (Bendtsen roughness, Bekk smoothness,
  • Parker print-surf roughness) and 
  • Profilometry Methods (contact or non-contact).

Typical roughness parameters:

  • (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

Methods and standards related to roughness and smoothness:

ISO 8791, ISO 5627, ISO 3274
Tappi T555, Tappi T479
DIN53108, ,   DIN 53107
BS 4420,  BS 6563