Optimum temperature and humidity in paint shops: brilliant results!

Painting with full control. Always eccellent finish and quality


Vaporizzazione acqua

In modern painting plants, constant innovation in the field of paint technology and the variety of surfaces to be treated requires specialized processes with well-defined application conditions. It is essential to create an air-conditioned and humidified environment according to precise technical specifications.

The optimal conditions for a successful result are a temperature range between +19°C and +24°C and a relative humidity between 40% and 60%. Of course, humidity management is essential, especially in the winter period.

Let’s see what humidity exactly means. The technical definition of humidity is the amount of water contained in a certain mass of air.  It can be expressed as an absolute value (grams in a certain volume of air) or as a percentage (relative humidity). Typically, the second value is considered. Humidifying therefore means adding water to the air.


Brilliant finishes and sustainable costs. The type of surface and the application area require specific solutions

The technologies available in the field of paints are very different from each other and vary according to the application support. Not only cars or heavy vehicles made of steel / aluminum, also other materials such as plastics and composites require very special attention for a quality paint job.

The application field adds further peculiarities such as the thickness of the film, the conditions of application and the quality of the result. The most specific sector is the aeronautical one, where every gram less of paint means fuel savings.

Aviation paints have reached a very high level of sophistication that requires specific application conditions, including controlled temperature and humidity. Just to give an example: in winter the conditions of application could be a temperature between +19°C and +24°C with a humidity level of 40-60% while in summer the temperature could be between +24°C and +28°C with the same humidity level.

These specific needs, always indicated in the product data sheets, lead to a new challenge: guaranteeing the required conditions while keeping operating costs under control.

Similarly for wood painting. Here, humidity is important both in the painting phase but also for the correct cross-linking process.

Let’s not forget the pharmaceutical sector and the specialized industrial processes.

Another aspect for which humidity control is important is environmental air conditioning. We consider, for example, rooms for residential use, health facilities, rooms for processing electrical, electronic and hybrid technology components.


Eco-efficient air humidification

It is simplistic to say that energy is a cost factor.

The real goal is to obtain the best result using the least amount of energy possible using heat recovery systems and the study of raw material costs. If we consider that in some application sectors the working conditions are within a certain range or optimal window, we just have to reach this target with the lowest cost. Humidity control requires an increased use of energy, because it is necessary to transform water from liquid to vapor (aeriform) so that it can be absorbed by the air.

Each change of state requires energy, but we can control the way the change of state occurs, making it more efficient and environmentally friendly.


The choice of the most suitable system: isothermal or adiabatic?

Humidifying means increasing the amount of water vapor within a certain volume of air. So the first step is to create water vapor: whether the transformation takes place through a gas or electric system that transforms water into steam (isothermal) or through the thermal energy contained in the air (adiabatic), a certain amount of energy is required.

The two systems have different strengths, the choice is linked to factors such as the space and the energy sources available. The air temperature and humidity conditions are closely related to each other and can be analyzed in the psychrometric diagram


Schema psicometrico: adiabatico
Adiabatic process
Schema psicometrico: isotermico
Isothermal process


Water is not just water: safety and maximum hygiene for the operator and for the equipment

Commonly used water contains mineral salts, microorganisms and other dissolved substances. Let’s focus on microorganisms: bacteria, algae and fungi. It is important to consider their presence when we have to treat the water and add it to the air we breathe. It is essential to avoid bacterial or fungal proliferation that can cause damage to our health.

The first step in the proper management of water is its purification. There are several treatment systems on the market: filters, osmosis systems, UV lamps and much more. Each system has its own peculiarities and different maintenance costs. The cheapest system does not always produce the necessary result and costs less to maintain.

When water evaporates, if not properly treated, it releases the mineral salts creating limestone while bacteria, such as legionella, can proliferate.

That is, in addition to becoming a problem for the operator’s health, it creates structural damage to the painting booths and heat-ventilating units, shortening their life. The water treatment is therefore a fundamental aspect for the correct installation of an adequate humidification system in a painting plant.


Verniciatura industriale in completa sicurezza

Air handling units for perfect paint processes. The right climate in all seasons

We must distinguish two situations: the winter or the summer season.

In winter, the outside temperature is low and with high relative humidity. Despite this, the absolute amount of water is very low as the cold air has a smaller volume and a lower capacity to retain water. By heating the air, the absolute amount of water remains unchanged but the volume increases, so the absolute humidity value will be very low (<5%) and far from the optimal working threshold of 40-60%. With these conditions, an air humidification system is required.

In summer, temperatures are much higher than the required set-point and humidity can vary significantly according to the geographic location. This means that it may be necessary to cool the air rather than humidify it. Although, with a low humidity level, the use of an adiabatic humidification system reduces the temperature at a lower cost than an air conditioning system.


Schema ciclo di verniciatura con umidificazione
1 – Prefilter
2 – Direct fired burner
3 – Intake fan
4 – Bag filter
5 – Humidification rack
6 – Droplet separator


Sizing, configuring and installing at the highest standards. A truly productive humidification system

To obtain optimal performance results, adequate section dimensions must be provided for the air passage, which ensure a good mix of air and water, in all operating conditions. It is also necessary to prevent the high temperatures of the curing phase from coming into contact with water to avoid bacterial proliferation.

Humifidation specialists. Business in action!

To obtain the best result it is important to rely on a partner who knows how to follow the entire design process, who evaluates the installation needs and knows how to advise the customer on the best cost / efficiency ratio of the system.

Blowtherm is always at the side of the Customer and his advisors, even on site, to find, together, the technologically correct and economically efficient solution. We know how to combine production needs, the characteristics of the installation site and the project external conditions.

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