In order for the quality of painting to be at the required level, a number of parameters must be taken into account:
- Relative humidity of the tree;
- Relative humidity in the room where the paint is made .;
- Air temperature in the room;
- Parameters of paint material;
- Paint temperature before application.
The relative humidity of the wood on which the paint is applied should not exceed 14%. If this indicator is exceeded, then it threatens with the following consequences:
- Bubble formation, especially on a polyurethane type coating;
- Peeling of the film from the paint;
- Excessive shine.
Humidity increases when you carry wood from a cold to a warm temperature. Most often, wood from birch, maple and beech gathers moisture in this way.
Quality standards state that the moisture content of MDF should not exceed 12%. If the paint is matte, then this indicator may be better, in this case there will be no problems with painting. If a glossy coating is used, humidity should remain at the recommended level. In this case, high humidity contributes to the formation of shagreen and unevenness. It is desirable that the inside be laminated and the humidity remain at the level of 8%.
Moisture exchange occurs regularly between the tree and the environment. It is recommended to store wood products after painting after grinding in a room where the humidity level remains in the range from 30% to 70%.
If there is a high level of humidity in the room where the painting takes place, this will negatively affect the quality of the paintwork. Defects in this case are identical to those deficiencies that appear on wet wood.
In addition, high humidity significantly increases the drying time of the product, especially for materials that are diluted with water. If the indoor air humidity exceeds 70%, then it is recommended to add 10% more hardener to the paintwork material than is used under standard conditions. It is worth noting that with high humidity in the room, dust particles from sanding run off, as a result they become invisible on an already dried paintwork. Therefore, the optimal indicator of humidity in the room is considered to be 50-70%. It is with this humidity that the coating is as even as possible.