How to Distinguish Between Genuine Galvanized Steel and Rusty One

Galvanized steel is known as a strong and corrosion-resistant material due to its zinc coating. However, not all products that appear to be galvanized are of the same quality. Some may even resemble galvanized steel on the surface, but the protective layer is actually very thin or damaged. Here's an easy way to distinguish genuine galvanized steel from rusted steel so you don't make the wrong purchase.

1. Look at the Surface Color and Shine
Genuine galvanized steel has a bright silver color with a metallic sheen. Crystalline patterns resembling "frost flowers" (spangles) are often visible on the surface.
In contrast, rusted steel is usually dull, brownish, or dark grayish, with some even showing red rust spots.

2. Touch the Surface
Genuine galvanized steel feels smooth and cool to the touch. However, if the protective layer is thin or damaged, the metal will feel rough and sometimes leave rust dust on your hands.

3. Test with Water

You can do a simple test by dripping a small amount of water on the surface.

• If the water drips off and doesn't stick, the zinc coating is still good.
• However, if the water spreads quickly and leaves brown stains after a few hours, it's a sign that the surface has begun to corrode.

4. Use a Magnet
The galvanized coating doesn't change the magnetic properties of the steel, but a difference in magnetic response can occur if the underlying surface is severely rusted.
Rusted steel usually exhibits a stronger magnetic response because the protective layer has been removed, leaving the pure metal underneath.

5. Look at the Edges or Cuts of the Metal
The edges or cuts usually reveal the true condition most quickly.
If the inside is still bright gray, the zinc coating is still protecting well. However, if the edges have begun to discolor or rust, the galvanized coating is starting to wear away.

Conclusion
Knowing the difference between genuine galvanized steel and rusted steel is crucial to ensuring the durability of the material in your project.
For best results, always purchase galvanized products from a trusted supplier like PT Intisumber Bajasakti (ISBS), which provides high-quality galvanized and galvanized steel, meeting SNI standards, and suitable for various construction needs.