Wooden fenestration: Colour is everywhere!

The purpose of a paint system is to provide protection to the structure, to decorate it, and to significantly improve its appearance.

There are many applications such as in the automotive industry, the furniture industry, building and paint construction, electronics, agriculture, even microelectronics, but also in road markings

The basic structure of the paint system consists of the following:

From the solvent (organic or water)
From the wetting agent
From the gloss factor
From the pigments
From the condenser

The two main categories of colours depending on the solvent

Organic: Conventionally, for example, oil paint
Pros: long open processing time (do not dry quickly), have high brightness and have reduced vein growth
Cons: high VOC (high emissions), fire hazard, hazardous to health, non-elastic fragile

Water-soluble: Acrylic paint, dye-PU
Pros: Fast drying time, no risk of explosion, permanent elasticity, good weather resistance, easy application, easy cleaning
Cons: increased veining, more grinding effort, fast drying.

Color and application is an important factor in producing a quality wooden window with great durability, BUT NOT THE ONLY factor.

What are the determining factors  for the construction of a quality window?

Timber Selection
Wood preparation
Painting and application of paint
Glass panels
Transportation & Protection
Acceptance Protocol from the customer
Care and maintenance

Choice of paint system: What is the purpose of a paint system in the construction of a window?

The paint system:
Protects the surface of the wood from moisture
Protects the surface of the wood from UV rays
Regulates the permeability of moisture in wood
Upgrades the surface of the wood

The paint system cannot:
Dry a wet wood
Provide protection to a poorly designed structure
Not forever stable without maintenance

You should keep in mind that depending on the wooden construction you should choose the appropriate product and the corresponding paint system.

What are these categories of wooden structures?
Stable construction (windows, doors)
Semi-stable construction (wooden houses, wooden cladding, etc.)
Non-stable construction (fences, pergolas, etc.)

We will consider the fixed structures that are windows and doors and initially make the choice of suitable timber, since not all types of wood make for the construction of windows. Different European directives define the suitability of the corresponding timber according to its stability (EN350-2016), resistance to moisture absorption and consequently to the appearance of fungi and rot.

The categories of timber are five
Classification according to DIN EN 350
class 1: very stable
class 2: stable
class 3: moderately stable
class 4: little stable
class 5: not stable

These categories refer only to those parts of the wood that come from the “heart wood” of the trunk and not from the outer parts (sap wood).

Categories 1 and 2 are suitable for the construction of windows, while categories 3-5 should be subjected to appropriate chemical treatment according to EN599 and DIN 68800 part 3.

Correct design of profiles

The sharp corners remove the paint. There the thickness of the paint is less than 10% of the desired layer. Good paint coverage is only possible on rounded corners.

Edge protection
A vulnerable point of wooden windows is the edges. Based on statistics, the largest percentage of damaged windows are caused by ineffective protection of edges.

There are suitable products that can be applied after impregnation and priming. This way we protect the paint and the window.

Let us observe two pieces of wood placed in a basin of coloured water. In one of them the special insulator has been applied while in the other one it has not. You see the intense influx of water into what was not protected.

Choice of paint system: Coating or lacquer?
Many times we will have to choose between the two depending on the stress that the windows and doors will have where they will be placed. Lacquers always have a higher resistance to UV radiation, while coatings should have a high pigment content in order to better filter out radiation. Colorless and lightly colored ones have low protection.

While very dark colours protect better but have the disadvantage of retaining radiation resulting in an increase in temperature on the surface of the wood. Therefore the choice should be made very carefully.

Paint application

After choosing the colour, the correct application of the paint should be done. The use of the appropriate equipment – paint gun, paint sprayer, beaker, etc. (according to the technical instructions of the paint), but also the appropriate conditions in the paint shop guarantee the correct application of the paint:
Air humidity: 60 – 70 %
Air temperature: 15 – 25 °C
Material temperature: 15 – 25 °C
Room air change: 15 times per hour
Rest time: about 15 minutes, after application of the impregnation and final coat. This results in an even and homogeneous layer of paint without bubbles.

We see that many factors affect the quality of a modern high quality wooden window

A good colour alone does not make a good window!

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