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Requirements for Colorants in Construction
The reason why Ultramarine Blue historically has not been used for cement coloration is because Ultramarine Blue is not chemically stable when is in contact with the cement paste. During the setting of mortar, different chemical interactions between them take place, so that the Ultramarine Blue’s chromophore is attacked and the blue color fades. During this chemical interaction there are two different reactions occurring simultaneously. First Calcium ions from cement are exchanged with Sodium ions from the Ultramarine Blue structure, producing some distortion in the crystaline structure of Ultramarine Blue. Second, because of the similarity of both structures, there is an overlap between the calcium hydroxide + calcium/aluminum silicate from cement paste with the Ultramarine Blue structure that favours the oxidation of the chromophore ( ); this combined chemical interaction leads to the complete fading of the blue color.
It is important to highlight that this effect is more critical under highly alkaline conditions, high water content or regular contact with water, for example in long setting times.
Being aware of the limitation of the current Ultramarines, the importance of this market, the few color alternatives designers and architects have and the potential for Ultramarine Blue in these applications, Nubiola has dedicated more than 4 years to a product development program in collaboration with a very prestigious R&D Centre for Construction and has launched suitable products to be used in this kind of applications.
Nubicem B series is a range of Ultramarine Blues specifically designed to be compatible in cementitious formulations. Thanks to Nubiola’s technology and knowledge in pigment encapsulation, Nubiola has succeeded in making a product that avoids (minimizes) the interaction with the cement paste.