opacity
That property of a material which restricts the
passage of light and thus prevents one from seeing
through it or seeing objects on or in contact with
the reverse side. Opacity is of considerable
importance in paper that is to be used for
printing. Tn printing papers opacity is measured
in percentages. e.g., a lightweight bond paper may
have an opacity as low as 79%, i.e., 21o of the
light that strikes it passes through, while a
24-pound bond paper of high opacity may rate a
percentage of 93, meaning that only 75 of the
light penetrates it. Different opacities may be
obtained by: 1) varying the paper pulp; 2) varying
the degree of hydration; or 3) using loading
materials and special opacifying agents. (17 , 350 )
![[CoOL]](/icons/sm_cool.gif){kind=icon}