CROWN MOLDING

While this ‘recipe’ may sound quite straight-forward, there is a whole lot more to the process of shaping raw gypsum into pieces of architectural art – and major landmarks across Finland depend on the outcome. Kipsilista crown molding adorns the walls and ceilings of Helsinki’s grand, historic Hotel Kämp, which was designed back in 1887; Kipsilista moldings also adorn the Belle Époque Grand Residence 21 apartments in Helsinki, originally designed and built by Swedish master painter and industrialist Per Erik Färlander from 1888-89. Modern and contemporary landmarks also rely on Kipsilista molding, including the Toyota Racing Head office, in Puuppola, and even the biggest mall in the nation, the Veljekset Keskinen Mall.

The company’s molding is intricately designed. Of course, detail is important, especially in these historical projects,” explains Dr. Thomas Gröer, Head of Technical Marketing, Industrial Solutions at WACKER SILICONES. “New molding has to match the original design perfectly, so the right silicone must be used, depending on the required processing time,” Dr. Gröer continues. “And the blended material results in a premium-quality molding: fireproof, moisture-free and designed to last many lifetimes, while retaining its detail and shape.” Building on these outstanding results, Kipsilista has expanded its offerings: most recently, the company has incorporated traditional crown-molding design with LED lighting.

When the moldings are made, the first one is framed on the table with plywood for extra edges. The mold is then filled with two-component silicone. Kipsilista moldings are made with WACKER ELASTOSIL^® VARIO 15 and VARIO 40, silicones recommended by supplier Lindberg & Lund, a member of the Biesterfeld Group.

“Because of their low viscosity, these silicones impart special qualities to the gypsum molding material, including no shrinkage and ease of processing,” explains WACKER’s Dr. Thomas Gröer, an expert in the use of silicone for a range of industrial applications. “And the curing time can be varied, depending on the shape of the molding and whether the process needs to be accelerated,” he continues. “With deep undercuts, for example, a softer silicone with good elongation properties is needed. The material is then ideal for more intricate details and has better resistance."

The gypsum is then delivered to Kipsilista in batches of 1,200 kilograms from Germany. The pure gypsum used by Kipsilista does not contain coal or other sandy substances often used in mass-produced plasterboards because of their low cost. Instead, Kipsilista uses artist’s plaster: It is completely recyclable, emission-free, non-flammable and non-shrinkable all factors that make for a superior-quality end product.

Production requires a series of careful steps. “The plaster is brought into our facility in sacks on a trolley and is moved close to the casting table. The plaster is then sprinkled into the water for mixing. The mixture is ready when the plaster powder forms islands on the surface of cold, clean water,” Hakala explains. The gypsum mass is mixed with a drill paddle. Next, the plaster is initially brushed across the surface of the mold by hand. This intensive and meticulous process prevents air bubbles from forming on the surface of the finished object. Next, a gypsum compound is added to the mold so that pre-cut fiberglass fabric (300 g/m2) can be pressed over and through it. This is an important step to ensure that the material can withstand future processing steps.

After Kipsilista’s plaster formulation has hardened for 21 minutes, the newly shaped material is carefully removed from the original mold and finally hung on a ceiling hook to dry. “The gypsum product contains far more water in relative terms than the corresponding concrete product. A gypsum product lifted from the mold weighs almost twice as much as it does when dry,” Hakala notes.