Chromadek® is lighter and stronger than any other roofing material, providing roofs of up to 80% lighter than those using concrete tiles. This saves on the roof structure, construction time and equally important the cost.
In light of certain colour coated steel product not reaching the expected life span, it is clear that all colour-coated steel sheeting does not comply with the design requirements for structural roofing materials. Due to Chromadek® being a well-established brand name, the name is being used generically for pre-painted roof sheeting. Authentic Chromadek® sheeting is imprinted with "ArcelorMittal South Africa Chromadek®" at regular intervals to mark it as the genuine colour coated steel product manufactured by ArcelorMittal South Africa.
Chromadek® is available as either Chromadek® Standard or Chromadek Ultim® designed for exposure and use in different atmospheric conditions:
Is intended for use under rural, Industrial (mildly chemically polluted) or moderate marine conditions.
Comprises a Z200 hot-dipped galvanized supstrate pre-primed with a primer (Dry film thickness (DFT) of 5µm) and finished with a final paint coat (DFT of 18 - 22µm) on the top surface.
A single backing coat (DFT of 8µm) is normally applied to the reverse side of the sheet.
Is intended for heavy industrial or marine conditions,
Comprises a Z275 hot-dipped galvanised supstrate, pre-primed with a chrome free primer (DFT of 20µm) and finished with a final coat (DFT of 18 - 22µm) on the top surface, giving a total dry film thickness of 38 - 42µm.
The reverse surface is coated with a 10µm corrosion resistant chrome free primer and a 10µm top surface paint system.
Steel is generally regarded as a rigid material offering only strength. This is not true of ArcelorMittal South Africa’s galvanised steel used as substrate for Chromadek®. It is readily formable which makes it eminently suitable for a wide variety of end-uses in the building industry. The formability of the substrate is matched by the flexibility of the paint system, two characteristics desired by architects, profilers and developers..
At ArcelorMittal South Africa’s Vanderbijlpark paint line, laboratory personnel conduct exhaustive tests on every coil of Chromadek® to ensure its formability and durability. The T-bend test is used to determine the resistance of the paint to cracking and/or detachment from the substrate. It gives an indication of the flexibility and adhesion of paint when it is deformed by bending through 180 degrees. No cracking and delamination of the paint is permissible. The primer and top coat on both sides of the sheet are tested for wet film and dry film thickness as well as for hardness and gloss after curing.
An important factor contributing to colour fastness means that every Chromadek® coil is subject to reverse impact testing for adhesion and a solvent rub test ensures proper curing.
Regular and ongoing maintenance ensures the superior corrosion resistance of Chromadek® reducing the requirement of frequent repainting after installation.
The appearance and properties of Chromadek® and Chromadek Ultim® can be safeguarded by proper handling, storage, installation and maintenance procedures. Chromadek® should be stored in a dry, well-ventilated area, clear off the ground. Sheeting should not be allowed to get wet while bundled or nestled in stacks. If a pack does become wet, the sheets should be separated as soon as possible and the surfaces dried with a cloth. Sheets should then be stacked so that free air circulation completes the drying process.
When handling Chromadek® on site, care should be taken not to damage the surface finish, see do’s and don’ts for Chromadek®
If the paint surface should become scratched - either during installation or later on - specially formulated air-drying touch-up paints are available. The surface would first have to be cleaned of any dirt, grease or chemical pollutants that might be present. Keep in mind that the UV resistance of air-drying touch-up paints cannot match the UV resistance of the oven-cured Chromadek® paint systems and the use of touch-up paints should be kept to a minimum.
When using Chromadek®, you are assured of excellent technical back-up.
To keep your Chromadek® roof in pristine condition for as long as possible, periodic washing down with water and a mild detergent prevents the accumulation of corrosive debris such as leaves, dirt and pollution fallout. This is especially recommended for both Chromadek® and Chromadek Ultim®.
Four Chromadek® colours (See Data Sheet C1.4), Charcoal Grey, Dark Dolphin, Aloe Green and Buffalo Brown, are produced by utilizing an advanced thermal technology paint system. This advanced paint system incorporates a heat reflective pigment providing an up to 8°C cooler benefit along with improved paint system durability. The paint system durability is measured according to its capability to maintain gloss, colour and film integrity.
The heat reflective pigments in heat reflective Chromadek® is chemically inert and highly stable allowing heat reflective Chromadek® to reflect more of the sun’s energy preventing the coating from directly absorbing energy resulting in less heat build-up resulting in longer life-cycles (less fading).
To gain insight into heat reflective Chromadek®, a demonstration recently showcased at UIA2014 titled “The heat reflective aspects of Chromadek®, what you imagine you can see” captures the strides made in paint technology that enables Chromadek® to become cooler.
An extract from the recent UIA2014 demonstration shows that “seeing is believing” when it comes to heat reflective Chromadek®. The key aspect of the demonstration shows the visible contrast between the same heat reflective and non-heat reflective Chromadek® colour.
The demonstration draws natural attention to the circled heat reflective colour appearing lighter therefore cooler, due to the heat reflective pigment, while the non-heat reflective colour remains darker therefore hotter. (NIR = Near Infrared)
In addition a darker colour can be configured through the application of heat reflective pigment to function as a lighter colour
To put this into a practical context
Where annual cooling loads dominate, a highly reflective and highly emissive colour coated steel roof is optimal for reducing energy consumption. Where annual heating loads dominate, an unpainted galvanised steel roof is more desirable because of its low infrared emittance.
Make the Chromadek® choice, the heat reflective benefit is a reality through