From experimental theory, the chemical composition of the coating oil should be determined. From the application point of view, it is a simple way to check the quality of the varnish purchased by the user.
1 Smell smell. UV oil solids content of more than 95%, the solid content of volatile substances is very small. Therefore, a good lacquer oil taste is small and should be less odor than printing ink. The smaller the smell after curing, the better.
2 measured solvent content. The varnish was placed in a graduated vessel (diameter less than 50 mm) and the paper was placed for 12 h to observe how much was evaporated. The decline in the surface position is generally not seen. If the drop is clearly observed, it means that there is too much solvent in the coating oil, which is a shoddy product that the original varnish was added with thinner.
3UV Varnish is a non-conjunctival material. Like edible oils, the surface will not be crusted for a long time. A small amount of varnish was placed on the surface of the glass piece, and the crusting phenomenon was observed after placing it in the light-shielding place for 24 hours. Non-skinning instructions are UV oils, otherwise false UV oils.
4 irritation to the skin. Put a small amount of glazing oil on the back of the hand and observe for 20 minutes to see if the skin becomes red or blisters. The good lacquer skin basically fails to respond, and the general lacquer will show erythema. The bad gloss oil will make the skin blister. .
5 Observe the color of the UV oil. The UV ink was placed in a transparent glass container. The lighter the color, the better the quality.
6 viscosity. According to different coating machine models, choose different viscosity, such as the ordinary three-roller, fangs polishing machine viscosity of 30 ~ 40s.
7 leveling. Check the print after curing, corrugated shows poor leveling. The solution is to reduce the viscosity, heat or add thinner; second, extend the coating and curing time to make it fully level and then cure.