The Problem of gelling when silicates are substituted for gum arabic in lithographic fountain solutions

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Title: The Problem of gelling when silicates are substituted for gum arabic in lithographic fountain solutions
Author: Wang, David
Abstract: The fountain solutions used for lithographic offset printing are solutions combining several chemicals. Each consists of water, some weak acid, gum arabic and alcohol in some fountain solutions, and some additives such as a nitrate, phosphate, bichromate, etc. This paper is a study of using polysilicate material instead of gum arabic in lithographic fountain solutions. Also, to solve the problem of silicate gelation by using the proper ratio of chemicals. The gelling problem of silicate material may be affected by the concentration, pH value, organic solvents and impurities, etc. Any one of the above will make the silicate material gel faster or retard the gelation. Hence, the kind of chemicals used are very important to the properties of polysilicate fountain solutions. The amount of those chemicals in the polysilicate fountain solution is also important for the gelling time. By controlling the ratio of chemicals, the gelling problem was solved with retarding of gelation. A pilot test, run by using a non-linear programming package, was done before the experimentation. The gelling time was prolonged long enough for lithographic fountain solution use. A series of press tests was accomplished with a Chief 15 duplicator to affirm the possible usage of polysilicate fountain solutions. The press tests also proved the gelling problem does not exist on the running press. After using the ratio of chemicals found in this paper, the polysilicate fountain solution can be practically in use.
Record URI: http://hdl.handle.net/1850/10127
Date: 1984-04

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