Lacquer is a general term for raw lacquer and refined lacquer.
Lacquer contains urushiol, laccase, gum, water and other main components. The drying of lacquer is to oxidize and polymerize the urushiol in the lacquer in the air through the oxidizing substances in the lacquer, so that the raw lacquer is dried in the air to form a film. The oxidizing substance in lacquer is laccase, which is a kind of oxidase and is an indispensable oxidizing substance when lacquer is dried naturally. There are two main points that affect the activity of laccase: one is that laccase has significant heat sensitivity, and its activity is the highest when the temperature is 40°C and the humidity is about 80%, but when the temperature rises to 75°C, its activity is within 1 hour. Totally destroyed.
Experience has proved that if the weather is too hot or too cold, or the environment is too dry or too humid when applying lacquer, it will not be easy to dry. The second is the acid value (pH) of laccase. When the pH value is 6.7, the activity is maximum. When the pH value is less than 4 or greater than 8, its activity disappears. Acid, hydrogen peroxide, potassium chloride, sodium diazonium, potassium, or sodium galvanic acid, etc., can partially or completely destroy the activity of laccase. Therefore, when storing and using lacquer, avoid contact with such substances. .It is better to store lacquer in the basement or cellar where the winter is warm and the summer is cool. If it is stored in a warehouse, it should be stored in a cool and wind-free place without sunlight. It should not exceed 30°C in summer and not lower than 0°C in winter. At the same time, pay attention to separate it from the vapor of acid, alkali, salt and other chemicals, pigment powder and various unstable substances, so as to prevent the lacquer from deteriorating. The laccase in lacquer is an oxidase, and the storage time should not be too long, and it is better to use it up within one year. The old lacquer of more than two years is difficult to dry, and it needs to be mixed with new lacquer to dry.
In order to adapt to the drying characteristics of lacquer, it is better to have a special room (or basement) as a drying room. The room is clean and dust-free, not ventilated, and the room temperature is controlled at 15 ℃ ~ 25 ℃; %about. This kind of drying room is commonly known as "yin room" and is used for drying lacquer coatings. Raw lacquer coating and lacquer putty are generally dried in this "shady room" for 12-24 hours.
