Application - Processing

On-Site Paint Coatings

Basic Principles

On-site paint coatings are possible, however, they will not reach the same quality as the coatings applied in the factory. Apart from the decorative point of view, a paint coating may also be advisable for reasons of physical conditions, as protection against moisture absorption. Although AMROC-PANELS are weather and rot resistant even without a paint coating, it is still a wood-based material, which can react to changes in the humidity of its surroundings, or to direct contact with moisture (e. g. when used as an exterior façade) resulting in small dimensional changes in length and width (swelling-shrinking behaviour).
See technical date.

A professional painting process decreases the swelling-shrinking behaviour by temporarily delaying or, depending on the kind of coating material, even reducing to a large extent the absorption of moisture. Façades which are subject to high climatological demands, must therefore always be provided with an effective paint coating.

A merely one-sided paint coating will cause a lack of balance in moisture diffusion between the two sides of the board, which can lead to a distortion of the boards, especially in façades and moist rooms. The back of the board should therefore be coated as well, to ensure an approximate balance in moisture diffusion. Especially for rear-ventilated façades this requirement is necessary, because the back of the board is affected by surrounding humidity. Moisture absorption may also take place in the periphery of the boards, through the cut edges; these should therefore always be included in the painting process.

Correct storage and processing must ensure that the boards do not absorb moisture prior to being painted. If not stored correctly, release of absorbed moisture at a later stage may lead to the water-soluble components of the hardened cement, like calcium-carbonate, easily reaching the surface and thereby lead to paint damage in the form of efflorescence.
The occurrence of efflorescence cannot be excluded with on-site paint coatings.

Choosing the coating materials

AMROC-PANELS have a pH-value of 11-13. This requires that all applicable coating materials be alkali-resistant. Many coating materials from different manufacturers meet this requirement.

The following products are tested and recommended by paint manufacturers:

Basically, it can be assumed that the choice of coating materials is determined by the requirements of the intended application.

In a complete coating system (priming, intermediate coating, final coating), all individual components should be obtained from a single manufacturer, to ensure compatibility.

Dispersion paints can cover all requirements. For façades, UV resistant dispersion paints in bright colors, rich in additives and with an acrylic base are recommended. Dark paint colors can only be used in combination with a calcium hydroxide stable paint coating. Solvent containing primers and coatings could be preferred by the manufacturer in view of effectiveness. However, it must be noted that building material classes Bl will be com-promised.

Technical data provided by the manufacturer are decisive for the application and processing.