Why is painting work difficult in winter?

Drying things

After drawing a line on a paper, the ink on that line is clearly not dry… Or the glue does not dry and is sticky… What would you do in such cases?


You may use your hand or a fan to blow air on the painted area, breathe on it, or place it in a warm place. In order to dry an object, the liquid contained in it must be evaporated.

To that end, temperature and humidity are important.

The above-mentioned “actions we take when we want to dry things quickly” are actions that are empirically known.



How things dry

I wrote that temperature and humidity are important when things dry, but how are they related?

Imagine you want to dry your laundry outdoors.

The higher the temperature and the lower the humidity, the more water contained in the laundry becomes water vapor and the more likely it is to evaporate.






Temperature and humidity are also important for paint drying

“Temperature” and “humidity” are also important for paints, especially for paints on building exterior walls and iron bridges.

This paint, which is mainly used outdoors, is called “solvent-based paint” and is a paint in which the resin remaining as a paint film is dissolved in an organic solvent.

Solvent-based paint differs from laundry not only in whether they evaporate “water” or “organic solvent”, but also in that the resin left by the chemical reaction becomes a three-dimensional, mesh-like shape and hardens.

There are several types of curing methods, such as oxidation polymerization type and reaction curing type.


What is the best climate for painting?

Specific construction conditions differ depending on the paint used.

However, it is generally said that the optimum climate for painting is

a temperature of around 25°C and

a humidity of around 65%.

The paint is also affected by the temperature of the painted surface.

If the temperature of the coated surface reaches around 50°C, bubbles will be generated in the coating film and the paint will not be applied properly.

On the other hand, if the temperature or the temperature of the coated surface falls below 10°C, the evaporation and curing reaction of the organic solvent will be delayed, which may interfere with the formation of the coating film.

In addition, when the humidity is high, that is, when it rains or snows, or when condensation or frost is likely to form, water adheres to the coating surface, weakening the adhesion between the coating films and leading to poor finish.


If the climate is not taken into consideration, the coating film may be repelled or wrinkled, resulting in poor durability and easy peeling.





Difficulty of painting depending on the season

As mentioned above, painting work is affected by humidity and temperature. Depending on the season, there are times when it is suitable for painting and times when it is not.



Difficulty ratings ★☆☆☆☆

It may rain due to the spring rain front, but the temperature and humidity are stable and it is a season suitable for painting. Be careful of the weather.


Rainy season

Difficulty ratings ★★★★☆

Due to the rainy season front, it continues to rain and tends to become highly humid. It is not very suitable for painting. We recommend that you avoid it.



Difficulty ratings ★★★☆☆

Although there are many typhoons, showers, and heavy guerrilla rain, it is often suitable for painting because there are many sunny days and the temperature is high. However, since the temperature of the painted surface tends to rise, it is necessary to consider painting from a time when the temperature is low (early morning, etc.) depending on the construction site such as the roof.



Difficulty ratings ★★☆☆☆

There is a possibility of rain due to the autumn rain front and typhoons, but except for that, the temperature and humidity are stable and it is a season suitable for painting.



Difficulty ratings ★★★★★

Painting is possible in areas that are dry and the temperature does not drop so much, but it is not possible in snowy areas from late autumn to early spring. In addition, freezing, condensation, and frost easily occur, and the temperature is often below 5°C, so painting work requires experience and technology. In addition, special consideration may be required such as building a roof to prevent snow from coming in, or covering the building with a curing sheet and then blowing in warm air with a large commercial heater (jet heater).



In this way, especially in winter, painting is more difficult than in other seasons, and it is better to avoid painting as much as possible.

If painting is unavoidable, you should avoid mornings and evenings and work during warmer days.



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