This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Paper which has been made sensitive to light by coating with a sensitive emulsion. When submitted to the action of light either a visible or invisible (latent) image is formed. The invisible image is made visible by the process of development, while the visible one is usually made permanent by the process of toning. Usually both images are made permanent by fixing in a bath of sodium hyposulphite. There are, however, various papers that are manipulated differently, some being made permanent by simply washing in water.
A coating placed upon paper, or used in the manufacture of the paper. Photographic printing papers are usually sized with a compound of alum and resin dissolved in a solution of soda and combined with potato starch. This is mixed with the paper pulp.
A chemically pure grade of paper used as a base upon which to place sensitive emulsions; usually employed by those who desire to sensitize their own papers. Manufactured at Mal-medy, Germany.
Blue and red litmus papers are used for testing the acidity or alkalinity of solutions. When blue litmus paper turns red it is a sign that the solution is acid, while if red litmus paper turns blue it is a sign that the solution is alkaline. If the solution effects neither red or blue litmus paper, it is neutral.
A material composed chiefly of paper. Prepared by pulping any kind of paper into a mass of doughy consistence; i. e., reducing paper to a soft uniform mass by tearing it into minute particles and then soaking in water. The pulp is pressed into a mould to the shape required. For making trays the pulp is rolled into thin sheets and then pressed into a mould, after which the surface is oiled or varnished. Owing to its lightness and toughness trays of this kind are very useful in photography.
A white, solid, colorless substance without taste or smell. Acted upon with great difficulty by other substances. Used in photography in connection with benzine for polishing ferrotype plates in order to give a special gloss and to keep prints from sticking to the plate when dry. After the ferrotype plate has been thoroughly cleansed with water and polished with cotton, a solution of benzine, I ounce, paraffine, 10 grains, is rubbed over the surface of the plate. After polishing the plate is rinsed in plain water and the prints placed in position.
(See Paper, Parchment.)
A picture-frame consisting usually of a pasteboard back and a piece of glass, between which a drawing, an engraving or a photograph is placed, the whole being held in position by means of strips of paper pasted over the edges. - (Century Dictionary.)