Rajdeep Narayan

Acidity, Alkalinity and pH pH is a measure of the acidity or alkalinity of a solution. It is defined as the logirathm of the acidity of dissolved hydrogen ions (H+ ). Hydrogen ion activity coefficient cannot be measured experimentally, so they are based on theoretical calculations. The pH scale is not an absolute scale. The concept of pH was first introduced by Danish Chemist Soren Peder Lauritz Sorensen at the Carlsberg laboratory in 1909. Sorensen suggested the notation “pH” for convenience. Standing for “power of hydrogen”. Using the co-logarithm of the concentration of hydrogen ion in solution, pH can be measured if an electrode is calibrated with solution of known hydrogen ion concentration. Pure water is said to be natural. The pH for pure water at 25oC is close to 7.0. Solution with a pH less than 7 said to be acidic and solution with a pH greater than 7 are said to be basic or alkaline. pH measurement are important for medicine, biology, chemistry, food science, environme...

  PRINTING INKS     CONSTITUENTS, PURPOSEN OR FUNCTION   CONSITTUENTS   1.      Pigments /   Dyes(used in liquid ink) 2.      Vehicle /   solvent(used in liquid ink) 3.      Dryers 4.      Anti-Oxidant   5.      Additives –Plasticizer INORGANIC PIGMENTS- inorganic pigments produced by precipitation(from yellow , cadmium red , bronze, trussing   blue ) are in termination use.   ORGANIC PIGMENTS – Organic pigment are mostly derived organic chemicals which are now mostly petroleum waste and most use at the visual spectrum can be match by   this pigment .   PIGMENTS   1.      Carbon black   2.      Transparent black   3.      Opack white   4.      Cadmium selenide   5.      ...

  SPECIAL TYPES OF INK   1.                 QUICK-SET INK: - Because coated papers and boards have a much more compact and less penetrate surface than uncoated stocks. The thick oils and varnish necessary in lithographic and letterpress inks are only slowly absorbed leading to the problems of set off in sheet fed and the possibility of blocking in reel fed operations. Low viscosity oils and solvents will be absorbed relatively very quickly. Quick set inks exhibit the principles of absorption drying by ink in cooperative a two part, oil system comparatively thin oil that is readily absorbed through the surface coating living the thicken oil, resin and pigment on the surface. The print then sets to a tough drying coatingwhich oxidation polymerizes more slowly to give a fully hardened film.   2.                 MOISTURE-S...

  THE PRINTING PROCESS AND SUITABLE INK Printing inks, in one fore or another, has been around since long before Johan Gutenberg invented printing with moveable type. Three hundred years before Christ, the Chinese were using inks to print wooden blocks. One of the earliest ink formulas included Lampblack, glue and water. This was later improved somewhat by addition of linseed oil, but it was not until the last 19th century, with the introduction of synthetic oil and man-made resins, that the quality of printing ink was greatly improved printing inks are complicated mixture of chemical compounds. The composition varies by printing process, by whether printing is sheet fed or web fed, and by substrate. Each printing process required an ink with different characteristics. The ink used is also determined by the kind and speed of the press, the surface to be printed, and the used for the most common printing processes, and the specific properties of each. LETTERPRESS INKS: -Design...