![]() Lithographic printing makes use of the chemical properties of oil and water to differentiate image and non-image areas of an aluminum printing plate. pH and Conductivity of Fountain Solution What are Fountain Solution, pH, and Conductivity? To clean up, place the covers back on the ink cans, fold and place scrap paper into a trash can, and wipe the ink off the ink knives and drawdown blade using a wiper with solvent. Visual evaluation of the drawdown shows that the opaque ink (left) covers the pre-printed black band more completely than does the transparent ink (right). Completed drawdown (shown from above) after drawing the blade down the length of the paper.įigure 2.5. Drawdown blade positioned above the two ink samples.įigure 2.4. (Dime shown for size comparison.)įigure 2.3. ![]() apart so they fit within the drawdown blade’s recess. Drawdown prepared on a pre-printed form with two dime-size droplets of ink spaced about 2 in. Label your drawdown sheet and hang on the plastic wall cover to dry overnight.įigure 2.2.Evaluate the opacity of both inks ( Figure 2.5).Scrape up any ink remaining at the end of the drawdown with a wide, 2-in.Place the drawdown blade on the paper, above the ink droplets, and slide it toward the end of the paper, so an ink film covers the preprinted black bars ( Figures 2.3 and 2.4).(5 cm) apart ( Figure 2.2), so they can be drawn down with one swipe of the drawdown blade. ink knife, place two dime-size drops of ink (one opaque and one transparent) near the top of the draw-down sheet, about 2 in. When finished with the test, fold the paper over and place carefully in a trash can. knife, and place the skin onto a piece of scrap paper. De-skin the ink if necessary: scrape the skin off the top of the ink using a 2-in. Remove the ink can covers using the opener.Place all the test components and tools on the ink table.two cans of ink of the same colour, one transparent and one opaque.ink knife, drawdown blade, and pre-printed drawdown paper. Drawdown components (left to right) include wipers, solvent, ink can opener, 1/2-in. This is one of the reasons why the test described below is an important quality control test. The pigment is normally transparent, but when it gets too hot during ink manufacturing the resulting process yellow ink can be slightly opaque. This is especially true for pigments used to manufacture process yellow. Sometimes it also possible that the temperatures that the ink is exposed to during the ink manufacturing process can result in a different opacity than intended. Certain pigments used for the manufacturing of the Pantone base colours result in opaque inks. The opacity of ink is determined by the pigment used and also by the interaction between the ink and the vehicles used in the ink formulation. A spot-colour ink will most likely be used alone but may need to cover previously printed inks. A process-colour ink (cyan, magenta, or yellow) needs to be transparent so overprints can reproduce multiple colours. ![]() Printing inks can be manufactured to be either opaque or transparent. Opacity is assessed visually after drawing down an ink sample on paper with a pre-printed black band, as shown in Figures 2.1–2.5. Ink opacity is a subjective evaluation of the ink’s ability to block transmitted light.
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