1.Are there defects or weaknesses in the coating itself that could cause the coating to be lost?
If the coating has tiny scratches, pinholes, bubbles, or the coating is thin at the edges or corners, the high-pressure water flow may "impact" the interface between the coating and the substrate through these gaps. Long-term or high-intensity washing may cause partial peeling of the coating (especially when the adhesion between the coating and the substrate is poor).
For thin coatings (such as decorative chrome coatings on the surface of household appliances, which are only a few microns thick), continuous flushing of high-pressure water flow may accelerate the wear of the coating, especially when the same part is repeatedly washed.
2.What effect will water gun pressure that is too high or distance that is too close have on the coating?
The pressure of household high-pressure water guns is usually 5-20MPa, and the industrial level can reach 30-100MPa. When the pressure exceeds the bearing capacity of the coating (such as ordinary zinc coating, decorative chrome coating), and the flushing distance is less than 10 cm, the impact force of the water flow may directly "break through" or wear the coating: For example, the zinc coating (thickness 5-20 microns) may be partially washed away and the base metal may be exposed under a pressure of more than 30MPa and a close-range flushing. Although the chrome coating has a high hardness (HV800-1000), it is relatively brittle. When the high-pressure water flow vertically impacts the corners, micro cracks may occur.
3.How does flushing angle and duration affect coatings?
Flushing vertically to the coating surface concentrates the impact force, which is more likely to damage the coating than at an inclined angle;
Continuous flushing of the same part for a long time (more than 1 minute) may cause fatigue wear of the coating due to accumulated impact, even at moderate pressure.
4.What are the situations that are usually less likely to damage the coating?
Thick coating and strong adhesion
For example, the hot-dip galvanized layer of industrial equipment has a tight bond with the substrate and good toughness. It is usually not damaged by household high-pressure water guns at a distance of more than 30 cm.
Automobile galvanized sheets are tested for adhesion before leaving the factory, and are generally not damaged by high-pressure water guns used for daily car washing.
Moderate pressure and standardized operation
In household scenarios, pressure ≤15MPa, distance ≥20 cm, and 45° tilted flushing have little effect on most qualified coatings.
Short-term occasional flushing has a lower risk of damage than frequent flushing.
5.What are the resistance recommendations for different coatings?
Hot-dip galvanized layer: more impact-resistant, unless subjected to long-term close-range high-pressure washing
Electroplated zinc layer: Thin coating should avoid close direct exposure to corners
Chrome plating (decorative): high hardness but brittle, avoid repeated impacts on the same area
Nickel plating: medium toughness, avoid high pressure direct exposure to pinholes