All glass surfaces must be properly cleaned according to how dirty they are. In particular, a sufficient amount of clear water must be used for this. Avoid aggressive cleaning agents (e.g. alkaline suds, acids, agents with fluoride content) as well as abrasive cleaning materials. These abrasive materials may only be used to clean off specks of dirt that cannot be removed in any other way.

The raw materials mean that all materials used in glass products have inherent colours that can become stronger as the glass thickness increases. To meet the statutory requirements in terms of energy conservation, coated glasses are used. Coated glasses also have an inherent colour. This inherent colour can look different when looking through and/or at the glass. Variations in the colour appearance are unavoidable, and can be caused by the iron oxide content of the glass, the coating process, the coating itself and changes in glass thickness and pane structure.

The lower the U-value (previously k-value) of an insulation glass, the lower the temperature of the outer pane at equal room and outdoor temperatures. As a result of the "radiation exchange" with the sky, the temporary build-up of condensation on the outer glass surface is possible on the outer surface of high-performance heat-insulating glass in corresponding climate situations (e.g. after cold, clear nights). This condensation recedes as soon as the pane heats up, for example as a result of sunlight. The condensation builds up for physical reasons, regardless of the insulation glass system, and does not constitute a defect.

In sunshine, the application of absorbent films and paints after installation causes intense thermal pressure on the glass with the risk of thermally induced pane breakage. If you know before the glazing is made that such films and paints are to be applied, the use of single-pane safety glass is recommended to reduce the risk of breakage.

Increased thermal pressure is also generated in glass if part of the pane is exposed to direct sunlight whilst another part is in the shade. These shaded glasses are heated up unevenly. The tension generated in the glass as a result of the uneven heating depends on factors including the intensity of the sunlight, the absorption of the sunlight by the glass and the geometric distribution of the sun-exposed and shaded glass surface sections.

A minimum distance of 30 cm must be maintained between radiators and insulating glass situated behind them. If single-pane safety glass is used as the inner pane of the insulating glass, the minimum distance can be reduced to 15 cm.

In sunshine, the application of internal shades after installation involves the risk of heat build-up between the shade and the glass. With regard to the distance from the glass and the installation situation, for example, the shade must therefore be applied in such a way as to avoid this heat build-up.

Stickers and labels on the glass have a special adhesive particularly appropriate for this purpose. They should be removed from the glass panes as quickly as possible. In particular, the stickers should not be exposed to sunlight for a long period of time. Different wetting behaviour compared with the rest of the glass surface is not entirely avoidable in places where stickers and labels have been removed.