It sometimes happens, that after the paper has been mounted and dried, it is discovered that lumps in the paste have caused defects to appear on the face of the paper in the shape of raised surfaces that unfit it for the intended purpose. These can be entirely removed by wetting the back of the strainer with some clean water immediately behind where the lumps of paste are, and with a knife scraping the cloth a little at these places; the surplus paste will work itself out through the cloth.
The starch paste used in mounting should not be made very thick; on the contrary, it should be as thin as is consistent with still retaining all its adhesive qualities. Should you fear that it is too thick or lumpy, strain it through a piece of cheese cloth. In a former edition of this book I advised adding to the paste a little white glue dissolved in warm water, but I do not now consider this necessary for crayon paper or photographic enlargements, and do not recommend its use except for mounting paper of unusual thickness.
The foregoing directions for mounting apply to platinum or silver enlargements, crayon or other kinds of paper, but not to bromide enlargements. The bromide paper requires a different method of handling on account of the gelatin surface, which when wet is destroyed by contact with any dry substance, as the latter removes the gelatin.
For determining the proper position of photographic enlargements (bust pictures) on the strainer, the following scale will be useful as a general guide. When the size of the strainer is 16×20, 20×24, 22×26, or 25×30 inches, the distances from its top to the top of the head of the portrait should be respectively 3-1/2, 4, 4-1/2 and 5-1/2 inches.
MOUNTING BROMIDE ENLARGEMENTS.
The first requisite for this is a water-tight tray, large enough to hold the enlargements. A hard rubber tray can be purchased, or a wooden one that will answer the purpose may be made. I use one of my own construction that is cheap and serviceable. It is simply a wooden box, 27×32 inches and 4 inches deep, made of 1/2 inch grooved material and lined with black oil cloth, not cut at the corners, but folded in. In this, when about half full of water, lay the enlargement face up, and let it remain in the water fifteen minutes. It should then be laid face down on the wet cloth (which should be all ready) as described in the preceding chapter, for mounting crayon paper. Care must be exercised to have the cloth wet all over, for if there should be any dry spots in it they would ruin the gelatin surface. With a cloth or squeegee remove the water from the back of the enlargement and also from the cloth around its edges, for if there is too much water on the edge of the cloth it will work up into the paste and prevent it from sticking when mounted. Now paste the enlargement and strainer according to the directions given for mounting crayon paper, place the enlargement on the strainer and rub it down by using the fingers wet in a little water, or the squeegee can be used; and then trim off even with the outside of the strainer. Avoid rubbing too hard along the edges, as by so doing you will press out all the paste and it will not stick.
You can remount a bromide enlargement as often as necessary in case it does not come out perfect, only bear in mind that you must not allow anything dry to touch the surface when wet. But I should not advise you to try more than three times directly on the strainer. It would be better to mount a piece of crayon paper on a new strainer, and after it is dry to remount the bromide enlargement on that.