This enemy is very dangerous: the car loses its presentation, and with it the price. But that is not all. Rust undermines the power elements of the body, the suspension - and the car actually falls apart.
How to contain corrosion? One of the most effective ways to deal with it is a zinc coating of steel parts. The thirtieth element of the periodic table has long been known as one of the most reliable defenders of steel, in addition, it is relatively inexpensive, affordable, and technologically advanced. Galvanized metal is widely used for the bodies of modern cars and this helps to prevent through corrosion for 15 years.
In industry, zinc is applied mainly by two methods - hot dip galvanizing or electrochemical deposition. Both require high costs - material and energy, in addition, they are not always applicable, especially for large structures and parts of complex shape. All this gave impetus to the development of the method of cold galvanizing - similar to the application of paints and varnishes.
Zinc coating protects the surface of iron (steel) in two ways. Either forms a mechanical barrier (insulation) from a continuous film of zinc oxide and salts, or in the presence of moisture, electrochemical (tread) processes are used when the material is used to repair defects in the coating itself, preventing iron corrosion.
Protection of the first type is more characteristic of hot-dip galvanizing (a continuous moisture-proof coating is immediately formed), of the second - for cold. However, in the latter case, in the presence of moisture, electrochemical processes change the structure of the coating, and it gradually begins to work as after hot-dip galvanizing.
Compositions for cold galvanizing, in order to provide active electrochemical protection of the steel surface, must contain in dry form at least 94% pure zinc with a particle size of 12-15 microns or at least 88% zinc with a particle size of 3-5 microns.
Zinc-containing primers in aerosol containers, mainly imported, are on sale. The most common "Zn-GRUNT" epoxy from Hi-Gear, besides the only one with instructions in Russian, directly on the bottle.
The use of all drugs (photo 1) is almost the same: the treated surface must be cleaned of rust, scale, old paint and degreased. To increase the protective properties, pre-treatment of the iron surface with phosphating agents (for example, phosphoric acid converters) will be useful. It should be borne in mind that the density of zinc is several times higher than that of the “binders”, and it precipitates in containers. Before use, such compositions need to be mixed well. Even after the ball in the balloon begins to move freely, the instruction recommends shaking it again and again for at least a minute.
The coating is gray, rather soft (which is especially noticeable if you apply a layer of three or four, as recommended). But on top you will surely apply the soil, and then paint this place in the color of the car - it will be stronger.
Of the formulations that we tested, it turned out to be the most difficult to mix Hycote's Zinc Priming product before use - the ball is lightweight, you need to shake thoroughly!
Naturally, we also paid attention to the effectiveness of nebulizers - anyone who has ever used such aerosol preparations will understand us. Mard-Hyde Weld THRU nebulizers and the already mentioned Hycote did not work very clearly (photo 2).
At the same time, we remind that after coating the spray channel of the aerosol can with any drying composition (this also applies to varnishes, paints, etc.), you need to clean it: turn the can down with the spray gun down and press until clean gas flows. Only in this way can one expect that the next time the can will be operational (the drafters of other instructions forget such an important detail).
Cold galvanizing, providing high protective properties, also attracts with its ease of use, affordability, and relative cheapness. The shape and dimensions of the machined parts do not play a role - moreover, they can then be machined again, welded, etc., and then galvanized again.
For motorists, the Zincor-Auto kit for electrochemical deposition of zinc may also be of interest. In addition to the main task, it allows you to pre-clean the damaged area by electrochemical rust removal and degreasing. The kit (photo 3) includes two bottles with solutions, two electrodes (one made of stainless steel, the other with a zinc tip) and a wire with a connector and a clamp.