To a pint of best grade gasoline, add as much parafine as the gasoline will readily dissolve and spread this solution evenly over the print with a soft brush, wipe dry with a piece of white cotton rag and print in the usual manner. Vandyke prints treated in this way will require only about two-thirds the usual time to print. Meadville, Pa. E. W. Bowen.
It very often occurs, when making blueprints, that a print becomes burned by over-exposure and the lines do not show up well. These may be brought out more clearly by pouring bi-chromate of potash, dissolved in water, over the print while it is in the sink. The print must be washed again with water before it is hung up to dry. Herbert C. Snow.
To prevent the annoyance occasioned by having blue-prints discolored by rain, drippings of mines or other similar exposures, a very simple method of waterproofing them may be effected as follows. The waterproofing medium is refined parafflne. To apply, immerse in the melted paraffine, until saturated, a number of pieces of an absorbent cloth at least a foot square. When withdrawn and allowed to drain for a few moments they are ready for use. Lay one of the saturated sheets on a smooth surface, place the dry print on top of it, and then lay a second sheet of the saturated cloth over it. Iron the top cloth with a moderately hot flat-iron. The paper immediately absorbs the paraffine until saturated, becomes translucent and highly waterproofed, owing to the smooth glossy surface, which is the result of the ironing. The lines of the print will be intensified, and the paper left perfectly smooth and easy to handle. T. E. O'Donnell.
After washing the blue-print in the usual manner, immerse it for half a minute or less in a solution made by dissolving a teaspoonful of potassium bichromate crystals in one-half gallon clear water. Then rinse the print in clear water and hang it up to dry. A galvanized iron or japanned tray may be used for the solution. Prints may be much overprinted and yet give beautiful clear whites and extremely deep blues, easily seen by the workman and a delight to the directors, the latter especially because the solution is quite inexpensive, and can be used over and over again until an objectionable precipitate forms. I have used this toning with Keuffel & Esser's paper and also with a number of local brands of blue-printing paper, all of which gave such fine results that we specify "all blue-prints must be toned."
Denver, Col. F. J. Schaufelberger.
We were bothered for some time with peculiar blue spots on our tracings, which were next to impossible to remove, and which caused spotted blue-prints. The office receiving these prints finally requested us to remove the ink blots from our tracings. The trouble was finally located, in connection with the blue-printing. The one doing this work had a habit of making one print, washing it at once to prove the color, and then printing the entire lot. Now after washing the first print, he did not thoroughly dry his hands, and on placing the next print, the paper was moistened and the exposure "fixed" some of the blue clear through the tracing cloth.
Howard D. Yoder.