THE PHOTOGRAPHIC NEWS, June 29, 1860, p.101
ON THE PREPARATION OF POSITIVE PAPER.BY M. ALEO.
1. Preparation of the Albumen:--Break the eggs into a graduated measure, carefully avoiding the mixture of yolk with the whites, and when the desired quantity of albumen is obtained separate the germs and pour the whites into a glazed earthen vessel, and to every 100 parts add 5 parts of a soluble chloride (that of ammonium is best), first dissolving it in as little water as possible. The quantity of water must not exceed one-tenth of the albumen, if a very brilliant surface on the proofs is desired. Beat the whites into a froth, and, after allowing it to settle for five minutes, remove the froth with a fork into a hair sieve, or muslin strainer placed over a second vessel. This operation to be continued whole of the whites are beaten into a froth and strained.
Allow the filtered albumen to settle for twelve hours; it is then ready for use. Draw sufficient quantity off into a shallow glass or Porcelain dish, without disturbing the sediment. It is a good precaution to strain it through a piece sponge placed in the neck of a glass or porcelain funnel. When circumstances permit, it is best to allow the albumen to repose four or five days before use. It appears to clarify itself, and gives a more brilliant surface to the positive paper.
2. Preparation of the Paper:--The positive paper must be carefully selected, and experimented upon. before the preparation of a large quantity is undertaken. If it be unequally sized, it will give uneven proofs and unsatisfactory results. Even the cutting of the paper to the required size demands much care, and only one sheet should be cut at a time, with an ivory paper-knife, without pressure or creasing.
Mark the back of the paper, and place it, sheet by sheet, carefully on the albumen without allowing the liquid to flow on to the back of the paper. This operation is best performed in damp weather, for then the albumen takes to the paper more readily, without forming bubbles, and the paper also dries more slowly and evenly. The first sheet floated is almost always defective.
Some little dexterity is required in floating the paper on the albumen ; the description of which is difficult, and necessarily unsatisfactory.
The time which the paper should be allowed to float upon the albumen will vary with the thickness and sizing of the paper: two minutes and a half may be taken as the average. It must not be reversed until it lies flat on the surface of the liquid. When this ensues, take the sheet by the two most distant corners, which, before it was floated on the albumen, have been previously folded back, and raise it slowly and regularly, so that the albumen forms a continuous, even coating over the whole surface. If the paper be raised too quickly, the albumen will flow down the paper in streaks, and the surface will dry uneven. By taking the paper at the corners most distant from each other, and suspending it to drain and dry in that position, the risk of drying unevenly is avoided.
3. Hanging and Drying the Paper.--The manner of hanging and drying the paper is one of the most important points, to avoid unevenness. The following method has always been successful, without causing any embarrassment to the operator:--Take two pieces of stout whipcord, and wax them, to prevent any fragments falling on to the wet paper; and string on each pieces of thin cork, of about an inch or an inch-and-half square, with holes pierced in the centre, through which the cord can freely pass. The cords are fastened to two walls, parallel to each other, with three bars of wood placed at equal distances along the cords to keep them apart; the distance must be a little greater than the width of the albumenised paper. Through each piece of cork a black-varnished pin must be passed upwards in a slanting direction, which penetrates the corners of the paper without difficulty. Care must be taken that the paper hangs fully distended and even, for, if it becomes curved, the albumen will dry upon its surface unequally. and spoil the proofs taken upon it. According to the extent of the operations, so may these suspending appliances be inch plied; they have the advantage of taking tip but little room, and are easily removed when the operation is over. The albumen that drains from the paper en be collected in dishes or on sheets of waste paper spread on the floor.
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