Editing Paperboard (section)

==Common terms==
'''Basis weight:''' in the US, it is the weight of {{convert|1000|sqft|m2}} of the same paperboard; the traditional British definition is the weight, in pound, of 100 of the same board<ref>[https://archive.org/details/dli.ernet.18571/page/168/mode/2up Page 169], ''Paper and Its Uses'' (1939 edition)</ref>

'''Brightness:''' Brightness is a technical term that is defined as the amount of blue-white light that a paper reflects.<ref name="twe">{{Cite journal
 | last1=Twede
 | first1=Diana
 | last2=Selke
 | first2=Susan E. M.
 | title=Cartons, Crates and Corrugated Board: Handbook of Paper and Wood Packaging Technology
 | publisher=DasTech Publications
 | place=Lancaster, PA
 | year=2004
 }}</ref> This property is very subjective and individual to each buyer and end use, as skin colour and food are better reproduced on 'warm' (yellow) whites and not blue whites.

'''Grammage:''' The [[grammage]] of the paperboard is assessed in accordance ISO 536.<ref>{{cite web
  |author=ISO: International Organization for Standardization
  |year=1995
  |title=Paper and board -- Determination of grammage
  |access-date=2009-07-18
  |url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=20674}}</ref>
Grammage expresses mass per unit area and is measured in g/m<sup>2</sup>.<ref name="twe"/>

'''PH:''' Surface [[pH]] is measured on a water extract and is on a scale of 0–14. 0 is [[acidic]], 7 is neutral and 14 is [[alkaline]].<ref>{{cite web|author=Iggesund Paperboard |year=2008 |title=Product Catalogue: General Technical Information |access-date=2009-07-18 |url=http://www.iggesund.com/Main.aspx?ID=d3f6ae98-6286-435d-bf6d-99a7ca881cab |url-status=dead |archive-url=https://web.archive.org/web/20110713004736/http://www.iggesund.com/Main.aspx?ID=d3f6ae98-6286-435d-bf6d-99a7ca881cab |archive-date=July 13, 2011 }}</ref>

'''Stiffness:''' Stiffness is one of the most important properties of paperboard as it affects the ability of cartons to run smoothly through the machine that erects, fills and closes them. Stiffness also gives strength and reduces the propensity of a carton to bulge under the weight of settling flowable contents such as cereals.

Although most paper strength properties increase with increasing sheet density, stiffness does not. A rule of thumb is that stiffness is proportional to the 1.6 power of sheet caliper.

The species of fiber used has an effect on stiffness, other things being equal. Northern softwood species impart superior stiffness compared to southern softwoods.

Other factors which affect board stiffness include coatings and moisture content.<ref name="twe"/>

'''Smoothness:''' Smoothness is particularly important when being used for printing, the smoother the paperboard, the better the image quality, because of better ink coverage. Smoothness is measured using air leak methods – the greater the rate of air leakage, at a specific air pressure, from under a cylindrical knife placed on the surface, the rougher the surface.<ref name="twe"/>

'''Caliper/thickness:''' In the [[United States]] caliper is usually expressed in thousandths of an inch (0.001”) or points, where a sheet of paperboard with a thickness of 0.024” would be 24 points. In [[Europe]] it is often sold in g/m<sup>2</sup>, however the thickness of the board is measured in [[micron]] (μm).

Paperboard also tends to be referred to with thickness rather than weight.<ref name="kir"/>

'''Whiteness:''' It refers ideally to the equal presence of all colours, because a truly white sheet will reflect all [[wavelengths]] of visible light equally.<ref name="twe"/>