The spectrum wall at Heureka shines brighter than ever
The spectrum wall at Heureka is a secret that passers-by can only see from a certain angle. During the last few months, it has been thoroughly renovated.
Heureka, located in Tikkurila, Vantaa, at the crossing of the main railway track and the Keravanjoki River, is one of the most popular tourism and leisure locations in Finland with approximately 280,000 visitors per year. At the Science Center, which was opened in 1989, visitors can learn about science and technology by doing science and experimenting.
At the end of 2014, the Heureka Science Center announced an expansion due to be completed by 2017.
– The spectrum wall is not a part of the expansion project or the renovation immediately connected to it. It is a part of the building's renovation program, which is progressing through different parts of the building according to the long-term plan and the annual repair plans, says Heureka's Facilities Manager Ulla Kortelainen.
Colors from the spectrum wavelengths
Heureka's façade on the side of the railroad tracks is covered by a glass wall with steel structures that illustrate the systematic division of visible light into different colors. The structures divide the 100-metre façade into 31 equal sections; the corresponding colors of the spectrum are based on analyses originally carried out in the laboratory of Tikkurila Oyj and the special hues created according to these analyses.
The steel was originally painted with solvent-borne Readur polyurethane paint (currently Temadur), but now the choice fell on Fontedur, a water-borne option. Because the water-borne products are tinted using different tinting colorants and colorant dispensers from the solvent-borne products, Tikkurila Color Service calculated new formulae for the colors.
Condition assessment revealed defects
Tikkurila's Technical Service Manager Juha Kilpinen inspected the condition of the paint on the steel structures of the Heureka spectrum wall in 2011.
– Visual examination showed that the topcoat had worn off completely at several points, and parts of it were also not well attached. In many places, mainly at different kinds of joints, the steel structure had begun to rust.
Instead of repairing the wall on site, re-painting at the paint shop in controlled conditions was chosen from among the recommended options for renovating the structures.
The structure of the frame has been assembled using bolted joints and consists of profile and pipe components, which means that disassembling the wall for surface treatment at the paint shop might be the most affordable option and provide the best end result. The corrosive parts of the structure could be repaired at the same time.
Disassembly and reassembly
The main contractor in the renovation of the Heureka spectrum wall was NCC Rakennus Oy, and Teräsnyrkki Steel Oy acted as its subcontractor.
The steel frame was disassembled completely, and the parts were moved to the Teräsnyrkki workshop in Hakkila, Vantaa. Because it would have been difficult to repair the old “vertical columns” due to major deformations, these were completely replaced. Similarly, the tension rods in-between the pillars were replaced with new ones. The new vertical pillars were manufactured in lots of approximately five pieces, in the same order as the reassembly was carried out. Teräsnyrkki was also responsible for disassembling and reassembling the glass sections.
Repainting the steel structures
The vertical pillars were painted with glossy Fontedur HB 80 polyurethane topcoat in several batches using 31 different hues, and all of the backing pipes behind the glass were painted with semi-gloss gray Temadur at the same time.
The application was carried out as wet painting, and no separate drying method was used. Because the Teräsnyrkki workshop did not have a great deal of previous experience with water-borne paint, the drying speed was studied before carrying out the surface treatment.
The manufacturer's instructions were followed with regard to the drying times, which were verified to match the temperature at the paint shop; this ensured that no problems occurred.
Before the surface treatment, the steel parts were washed and cleaned to preparation grade Sa2½. The painting was carried out using the system described below, which gives the paint an expected life of 15 years in exposure class C3 (SFS-EN ISO 12944-2).
Temazinc 99 60 µm
Fontecoat EP 50 Beige 80 µm
Fontedur HB 80 60 µm
Total 200 µm
Text: Arja Schadewitz. Photos: Aki Schadewitz.