Sharp Scale
Encyclopedia
The Sharp Scale was devised by Henrietta Sharp Cockrell as an objective and scientific way to measure the opacity
-translucency of paper, particularly of manuscript folios, 'in the field' without specialized equipment, for example in a museum or library setting.
The folio is held at a distance of 15 cm. from a constant 60 watt
light source (such as an unshaded table lamp). A dowel (or pencil) is held behind and against it, creating a silhouette. Folios are added until the outline of the pencil is no longer visible. The number of the folios needed to obscure the silhouette of the pencil is recorded.
Opacity (optics)
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc...
-translucency of paper, particularly of manuscript folios, 'in the field' without specialized equipment, for example in a museum or library setting.
The folio is held at a distance of 15 cm. from a constant 60 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
light source (such as an unshaded table lamp). A dowel (or pencil) is held behind and against it, creating a silhouette. Folios are added until the outline of the pencil is no longer visible. The number of the folios needed to obscure the silhouette of the pencil is recorded.