Wood paint, wood stain, polyurethane wood finish, wood oil, and lacquer are different in their properties and uses. Which one should you choose?

Introduce the differences between wood paint, wood stain, polyurethane, wood oil, and lacquer, along with guidelines for choosing the right application based on surface, durability, and project characteristics to ensure the wood remains beautiful for a long time and is cost-effective.
Knot Staining issue on colored film

The issue of wood sap seeping onto the paint film, the seepage of wood sap from the wood surface, and the resulting color stains on the paint film, what causes it, how to fix it, and what prevention methods are available.