The enemy of steel: Corrosion
As the structural support for the colored stone tiles, once the steel base material gets rusty, the entire roof system will be at risk of failure: the tiles will deform, develop leaks, and the colored sand will flake off, ultimately leading to roof leakage. To protect the core steel, we must pre-coat its surface with a layer of "sacrificial anode" or "barrier" metal, which is commonly referred to as a "coating".
In the ceramic tile coating industry, the two main types of coating technologies currently in use are: galvanization and galvalume coating.
II. Galvanized vs. Aluminized Galvanized: Which Has Longer-lasting Protection?
To visually demonstrate the difference between the two, we have cited a set of industry-recognized accelerated aging test data
| Galvanized coating | Core element | Protection mechanism | Corrosion rate under extreme salt spray testing |
| GI | 100% ZN | Sacrificial anode protection: Zinc corrodes before the steel, thereby protecting the base material. | Faster. Once the zinc coating is completely depleted, the steel plate will immediately become exposed. |
| GL | 55% aluminium + 43.4% zinc + 1.6% silicon | Barrier protection + sacrificial anode protection: The aluminum layer forms a dense oxide film to prevent moisture; the zinc layer provides local sacrificial protection. The two work together. | Extremely slow. The overall corrosion resistance is 3 to 6 times that of galvanized steel plates of the same thickness. |
Why is 55% galvanized zinc the golden ratio?
The "barrier effect" of aluminum: When the aluminum in the coating comes into contact with air, it will quickly form a dense and chemically stable oxide aluminum film. This film is like a perfect "shield", completely blocking water and oxygen from reaching the steel substrate. The "electrochemical protection" of zinc: Although aluminum provides an excellent overall barrier, at the cutting edges or scratches, the steel substrate may still be exposed. At this time, the remaining zinc layer will come into play and act as an anode, being corroded first (that is, sacrificing itself) to provide temporary electrochemical protection for the exposed steel. This "barrier + sacrifice" dual protection mechanism gives 55% galvanized zinc steel plates extremely excellent long-term durability, especially suitable for roofing materials like color stone tiles that are exposed all year round.
III. Intesa Standard: It is not just aluminized zinc, but also high weight and high quality. Just knowing that the substrate is aluminized zinc is not enough. High-quality colored stone tiles also need to meet the standard in terms of coating weight.
1. Coating weight: The key parameter that determines the lifespan. In the colored stone tile industry, the thicker the coating, the longer the anti-corrosion lifespan. Market low-end standard: AZ60. Products of this type can only maintain about 10 years without rusting in coastal environments. Engineering standard (the standard that Intesa adheres to): AZ100 - AZ150. Ensure that the base material has a physical lifespan of 30-50 years, which is also the physical basis for our colored stone tiles to achieve a long lifespan commitment.
2. Crystal structure of aluminum-zinc alloy: A more microscopic quality gap. High-quality Galvalume steel plates, the aluminum-zinc crystalline structure on their surface (usually in the form of fish scales) should be clear, fine, and evenly distributed. If the coating composition is not pure or the cooling process is improper, the crystals will appear coarse, sparse, which will reduce the density of the aluminum layer, thereby affecting the anti-corrosion effect.
