The pH value of the water-based ink is measured by a special test table. Generally, the pH value is required to be around 8.5, and the water-based ink is relatively stable within this value. In the process of use, with the rise of temperature and the volatilization of ammonia in the ink, the pH value will change, which will affect the printability of the water-based ink. A small amount of stabilizer can be added to control the pH. In normal printing, flexo printing machine usually requires adding 5ml of stabilizer every half an hour, and stirring it evenly, the water-based ink can maintain a relatively stable normal printability. However, stabilizers must not be added at will, otherwise it will affect the quality of printing, and various printing defects will occur. Viscosity is preferably measured by a No. 2 Zion cup. The viscosity of water-based inks of different brands is slightly different, usually about 25 to 30 seconds, and the viscosity can be slightly higher when printing dots. When the viscosity is high, it can be adjusted with a small amount of purified water. Of course, the addition of stabilizers can also play a role in reducing viscosity. However, with the increase of temperature and the change of printing speed during the printing process, the viscosity of the water-based ink will change. The operator should always check the viscosity of the water-based ink in the ink fountain and make appropriate adjustments. The knowledge of flexible packaging bags is here: http://www.yltpacking.com!
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