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Video: Red, Pink Or Orange?
The color of facade coatings changes again and again. What are the causes of these color deviations and what should the painter do to avoid complaints? Dipl.-Ing. (FH) Hans-Joachim Rolof The client wants a specific color for the facade: light yellow, ultramarine blue, red. This shade should be available at least for acceptance. Even if this succeeds: after four to five years there is a complaint, now the color has changed! How can the painter proceed to avoid discussions and complaints by the customer? BFS Leaflet No. 26 "Color change of coatings in the outside area" from the Federal Committee on Color and Property Protection serves as an aid. The leaflet applies to facade coating materials in accordance with DIN EN 1062-1 and solvent-borne or water-borne varnishes outdoors. From the perspective of the expert, practical experience on this new information sheet is reported below. Attention: The BFS information sheet No. 26 does not apply to color deviations for acceptance. Such deviations from the construction target are dealt with in BFS Leaflet No. 25 "Guidelines for the Assessment of Color Matchings and Color Deviations". Causes of the color change Color changes occur depending on the period of use, the type of use and the intensity of the environmental influences (e.g. UV radiation, irrigation, etc.). Color changes are influenced by the type of binder, the type and proportion of pigments and fillers, the additives, etc. When selecting a coating material, the substrate (the building material and its condition), the structural conditions,the location of the building and the surface effect are crucial. Product-related influencing factors are the type of pigments (organic or inorganic), the type of binder, the gloss level of the coating, the pigment volume concentration (PVC) and the brightness of the color. The substrate can have a negative effect on color stability due to alkalinity, different structure with the same coating material, soluble wood constituents or plasticizers. The BFS leaflet contains so-called Fb codes (color fastness codes) to predict the possible age-related change in the color of coating materials. These consist of a class (binder base) and a group (color pigment), are based on general experience and apply to products of medium quality. Coating material after binder:
- Class A: silicate paint, emulsion paint with a high binder content, acrylic paint, PUR paint
- Class B: emulsion paint, matt, silicone resin paint, dispersion silicate paint, alkyd resin paint
- Class C: dispersion filler paint, lime paint, colored mixed polymer resin paint, epoxy resin paint
Color pigment after lightfastness:
- Group 1: very good lightfast inorganic pigments
- Group 2: good lightfast organic and / or inorganic pigments
- Group 3: limited lightfast organic and / or inorganic pigments
The visually perceptible changes to be expected after about three to four years outdoors are given as follows for the different classes (without changes due to color pigment): For facade coatings:
- Class A: barely visible chalk
- Class B: visible chalk
- Class C: clearly visible chalk
For paint coatings:
- Class A: barely visible chalk, barely noticeable loss of gloss, barely visible yellowing
- Class B: visible chalking, noticeable loss of gloss, noticeable yellowing
- Class C: clearly visible chalking, significant loss of gloss, marked yellowing
The leaflet also contains a request to the manufacturers to identify their products on the labels and in the technical leaflets with the appropriate Fb code. But is that really enough? Is the advice on site and the color selection at the customer not much more often done using color cards? Shouldn't the "Color card" advisory tool include a list of the Fb codes with the associated coating materials? The color cards will certainly be bigger in the future, since the prints on the back take up more space. Tips for the painter Section 6.2 "Recommendations for the processing tradesman" is important for the processor. Below it is stated that the processor can only make an exceptional assessment based on the binder and the color of a coating material,whether a product tends to change color. And further: "(…) Without special product experience, due to the influencing factors described, he cannot make any definite statements about the extent and after what time the color of a coating material changes (…)". There are basically two options for advice: If a color is specified as a building target, the contractor can achieve a higher quality class (A before B before C) by choosing a different binder base. However, compatibility or suitability for the subsurface must be observed, as otherwise damage can result. If a coating material is specified, for example because of certain property requirements, a higher color stability can be achieved by selecting other color pigments from a higher group (1 to 2 to 3). This also gives the painter an instrument for greater added value: if the customer values a certain color, then the higher quality coating material may have to be used - which costs because quality has its price. So you can earn more with risk awareness as part of a consultation if the customer follows the advice. New duties: new risks? Finally, the BFS information sheet states: "(…) The processor is not obliged to provide general information on color stability (…)". No tradesman should rely on this advice without legal advice, in case of doubt one should think of the contractual agreements, because the lawyers are of the opinion: Pacta sunt servanda - contracts must be observed!This also applies to the promised or agreed color as an assured quality - unless the customer has been informed beforehand: information remains a must!
Dipl.-Ing. (FH) Hans-Joachim Rolof is a master painter and ö.buv expert. Since 1993 he has been a managing partner in the iba institute Gottfried & Rolof with headquarters in Koblenz and branches in Düsseldorf and Stuttgart. On March 11, 2010 in Höhr-Grenzhausen, the iba Institute is organizing the iba BauFach symposium "Façade & Space: Insulate properly, plaster properly - energetically optimal" on the subject of ETICS and energy saving. Information is available at www.iba-institut.de.