In electrolytic galvanizing, the zinc layer is deposited electrolytically (flow through product and liquid) from an aqueous solution of zinc (see question 2). The layer is smooth and smooth. The layer thicknesses vary from about 5 to about 40 µm. The layer thickness is determined by the current density and the duration in the zinc bath. Unfortunately, the distribution of the current density across the product is not uniform. This means that the layer thickness is higher in certain places (outside / protruding parts) and lower in certain places (inside corners / inside sides). The current always searches for the path of least resistance. The inside of tanks or pipes, for example, can only be electrolytically galvanized if a so-called 'auxiliary anode' is applied on the inside, with which we reduce the distance to be traveled for the current at that location.

After galvanizing, the layer is passivated (also called "chromated" or "bichromated"), which greatly increases the corrosion resistance and enhances the appearance. The passivation layer is a thin zinc chromate / zinc oxide layer on top of the zinc layer. The passivation layer can be applied in different colors, namely blue, yellow, green and black. From blue to green, the chromate content of the layer increases, the layer thickens slightly and the corrosion resistance improves. Black passivation is often used for visual applications. The layer is nicely smooth, semi-glossy black and is in terms of corrosion resistance between blue and yellow. With a product that is well galvanized and yellow passivated, the passivation layer may account for half its life (up to red rust). This should be duly taken into account when comparing with hot-dip galvanizing.

The highest temperature in electrolytic galvanizing must be sought in the pre-treatment and in most cases is a maximum of 70 degrees Celsius. So there is no risk of deformation of thin material. However, hydrogen gas is produced during electrolytic galvanizing, which can be included in the material structure especially with hardened steels. This creates "hydrogen embrittlement". After galvanizing, this hydrogen gas can be expelled again by heat treatment.

In hot-dip galvanizing, the product is immersed in a container of liquid zinc. A large block of zinc is heated to about 400 degrees and has melted. During dipping, the product is covered with a layer of liquid zinc and immediately after clotting, this layer solidifies. The layer is less glossy and usually even matt-gray after a few days. The layer thickness is not determined by the time in the bath. Only the thickness of the material influences the layer thickness (the thicker the material, the thicker the layer). The layer thicknesses are at least approx. 60 µm. and can sometimes reach up to 200 µm. Drip formation and deformation of thin material (approx. <5 mm.) Are disadvantages of hot-dip galvanizing. The advantage of hot-dip galvanizing is that it precipitates everywhere on the product, including on the inside of tanks and pipes.