Glossary - Paper Properties - Paper Weights


Paper manufactured in an alkaline environment. Acid-free paper typically has good aging characteristics and has no detrimental effect on materials that are in contact with it.

All French Paper products are acid-free and can be considered archival quality.


Brightness is measured as the percentage of light in a narrow spectral range reflected from the surface of a sheet of paper. It is not necessarily related to color or whiteness.


Thickness of a paper sheet, measured in thousandths of an inch. A micrometer is used to measure the caliper.


Pulp produced without using elemental chlorine for bleaching. This method significantly reduces the amount of harmful waste produced by the pulp bleaching process and prevents carcinogenic byproducts.

All French papers are produced ECF.


Direction of predominant fiber alignment, usually the machine direction. The directionality of paper must be taken into account in measuring such paper strength properties as tear, tensile and folding endurance. Grain direction can also influence the curl of a cut sheet if it is stretched or moistened.

French grain directions are indicated by the dimensional order of the sheet size. For example, 25x38 would indicate the grain is long in the 38" direction. If the size is listed as 38x25, the grain will be long in the 25" direction.


Measure of the percentage of light passage through a sheet of paper. The more opaque a paper is, the less show-through there will be from printing on the sheet below.


Treatment of paper to resist liquid penetration (ink, paint, water) using wet-end additives or surface application (starch solution).

All French papers have received a sizing surface treatment.