In the packaging and printing industry, it is often necessary to identify the varnish. Theoretically, the chemical composition of the varnish should be measured. From the perspective of application, a simple method is used to check the quality of polishing oil purchased by users.Quality discrimination of polishing oil.
Smell the smell. The solid content of UV oil is more than 95%, and the volatility of solid content is very small. Therefore, a good varnish tastes less than printing ink. The smaller the odor after curing, the better.Quality discrimination of polishing oil.
Measure the solvent content. Put the polishing oil into a graduated vessel (diameter less than 50mm), place the paper for 12h, and observe how much volatilized. Generally, there is no decline in the position of the surface. If a significant decrease is observed, it indicates that there are too many solvents in the varnish, which is a poor product with diluent added to the original varnish.Quality discrimination of polishing oil.
UV varnish is non conjunctival. Like edible oil, it will not peel on the surface after being placed for a long time. Place a small amount of varnish on the surface of the glass sheet, and observe whether there is scaling after placing it in the dark place for 24 hours. No peeling indicates that it is UV oil, otherwise it is fake UV oil.Quality discrimination of polishing oil.
Skin irritation. Place a small amount of varnish on the back of your hand and observe for about 20min to see if the skin turns red or blisters. Good varnish skin basically fails to respond, while general varnish will show erythema, and bad varnish will make the skin blister.Quality discrimination of polishing oil.
Observe the color of UV oil. Put UV ink in transparent glassware and observe. The lighter the color, the better the quality.Quality discrimination of polishing oil.Viscosity. According to different polishing models, the viscosity of the ordinary three roll and tooth holding polishing machine is 30 ~ 40s.Quality discrimination of polishing oil.
Leveling. Check the printed matter after light curing. If there are ripples, it indicates that the leveling is not good. The first solution is to reduce the viscosity, heat or add diluent; The second is to extend the coating and curing time, make it fully level, and then cure.Quality discrimination of polishing oil.