SECOND METHOD OF PRINTING ON IODIZED PAPER.
TAKE 30 grs. iodide potassium, 33 grs. nitrate silver; dissolve the above, together, in 5 oz. water. The precipitated iodide of silver is well washed in several waters; after the last washing the measure of water upon the moist iodide of silver is made up to 11/2 oz. water, to which is added 274 grs. iodide potassium ; as this dissolves it will gradually take up the whole of the precipitated iodide of silver, forming a clear solution. A wash of this,solution is applied to one side of the sheet of paper either with a glass rod, cotton brush, or by floating the paper on the surface of the liquid, poured into a flat porcelain dish.
The paper should be allowed to absorb the solution (whichever way it is applied) for three minutes ; after this it is hung to dry, and when dry is soaked in water for one hour; then removed and hung to dry, and preserved in a paper case for use.
Paper prepared with the first wash will keep good for two months, if preserved in a portfolio, under pressure. The paper, just previous to being used, is excited with the following solution, either by brushing over, or floating on the surface of the liquid: 10 grs. nitrate of silver 1 oz. water 1/2 dr. acetic acid.
If the solution is to be applied with a cotton brush or glass rod the quantity is to be taken by measure corresponding with the size of the paper; for a sheet 10 in. by 8 in. 1 drachm will be sufficient; if more than this is applied it will only be wasting the liquid. After remaining in contact with the exciting liquid for three minutes, the paper is hung to dry in a dark closet; and when dry, or nearly so, it is ready for use: it can now be placed in the pressure frame for the same time as the paper prepared by first method with iodide of silver,from five to fifteen seconds.
After removal from the pressure frame it should be developed by applying to the sensitive side 4 drms. of a saturated solution of gallic acid. After the application of this wash the picture will quickly appear; and when it has nearly acquired its full development, 4 drops of the exciting silver solution is applied to give increased depth to the shadows of the picture.
The drawing is now washed slightly in water, and immersed in the fixing liquid, where it must remain until the yellow iodide is entirely removed. The hypo-sulphite of soda solution is of the same strength as for fixing the picture in the first process for printing with iodized paper. Also the same precautions with regard to the choice of paper are necessary.
The results are very much influenced by the quality of the paper. The paper that is found to make the best negatives will also make the best positives: only that the sheets not thought good enough for a negative drawing, from having imperfections and slight defects in texture which might interfere with the printing qualities of the negative made with it, will serve very well for positive printing.
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