Halation and its Preventions.

Progress, Volume VI, Issue 12, 2 October 1911, Page 829

Halation and its Preventions.

Halation is the term given to the halo which often surrounds windows in photographs of interiors, and blocks up the details. Also it is found to occur in landscapes taken in a strong light, the tops of

trees and other objects which are surrounded by strong light being lost in a mist, or entirely obliterated. It is caused by reflection from the back of the plate, and occurs most strikingly in plates of the cheap class, which are thinly coated. With very thickly coated plates it rarely occurs, except when taking brightly lighted interiors. To prevent it the back of the plate may be coated with a mixture of powdered burnt sienna J /{>oz., gum arable Vjo/,., glycerine loz., water soz. This is readily washed off before development. A specially ready-made preparation of this is sold for this purpose if preferred. Another way is to cut dead black needle paper, or black American cloth, to the size of the plate, coat it with glycerine and squeeze it on to the back of the plate when placing it in the slide.