The construction speed of the fire-resistant spraying coating is very fast. The sprayed surface is equipped with anchor components to support the sprayed coating. The surface of the fire-resistant sprayed coating needs to be repaired after spraying because the thickness of the sprayed coating should meet the thickness required by the user. When spraying the paint, the mixture is continuously fed into the spraying machine. The material is sent to the nozzle by compressed air, with the air pressure controlled at 0.5m 12 to 0.19MPa, and the water pressure at the nozzle is controlled at 0.14 to 0.21MPa to ensure that the material is fully mixed. 

When applying paint, the operation of the spray gun is extremely important. It is necessary to ensure the quality of the sprayed coating and reduce the rebound rate. The key parameters of the spraying construction process mainly include the distance and angle between the nozzle and the surface being sprayed, the amount of coating water added, etc. This is the core of the spraying construction. During spraying, the distance between the nozzle and the surface being sprayed should be controlled within 0.8 to 1.2 meters. In actual operation, it is determined according to the type of coating and the outlet pressure. The nozzle of the spray gun and the spraying surface should be kept vertical, and the coating should be directly sprayed onto the spraying surface. Due to the high quality of the aggregate spray paint, it is prone to rebound at the middle part of the spraying material flow. The quality of the refractory powder and the adhesive is very low because the movement of the powder outside the spraying material flow causes serious flying at the site. Therefore, the amount of powder should be controlled, and the sprayed coating should not be uneven or peeling. 
When the distance between the spray gun nozzle and the spraying surface is 1 meter, the spray gun should move along a circular path, with the diameter controlled within 300 to 400 meters. Try to spray to the designed thickness in one go, and the spraying area should not be too large, generally controlled at 1.0 to 1.5 square meters. After spraying, expand the spraying range. When spraying fireproof coating, 2% to 4% of water should be added to prevent powder from flying during transportation. The remaining water should be added to the spray gun nozzle. The water consumption for heavy and light fire-resistant sprayed coatings is 10% to 14% and 12% to 20% respectively. When the type of fire-resistant sprayed coating, the pressure of the nozzle and the distance are fixed, the water volume should be such that the sprayed coating does not flow, and the water volume should be stable. Under the premise of ensuring the quality of the sprayed coating, add as little water as possible to obtain a good performance sprayed coating. 
The painting sequence is to spray in sections from top to bottom. Every 1-2 meters, a 1-3-meter-wide expansion joint is reserved. If the spraying construction is interrupted, a stepped joint spraying should be carried out at the expansion joint. If the coating layer is set, a knife should be used to cut the stepped joint connector of the expansion joint. When the fire-resistant coating is just solidified, the surface should be trimmed with a knife. If there are any looseness, drying, or cracks, they should be removed promptly and re-sprayed. After the spraying is completed, natural curing until initial setting, and then watering for moist curing for 3 days. 
How to handle the spraying of polyurea substrate? 
1. Concrete base treatment: Spray the concrete prefabricated pieces with a blast of air, or use an angle grinder and a high-pressure water gun to remove dust and debris from the surface. After the base material is completely dry, use filling materials to level the surface. Once the sealing material has cured, use an angle grinder to polish the areas that need sealing. Then remove the surface dirt, apply a layer of matching primer by brushing or rolling. The heavy re-coating interval for the primer is 24 hours, and the small interval is 3 hours. 
2. Metal substrate treatment: The substrate is sandblasted to the SA2 5 level. Defective areas such as weld seams are leveled with epoxy putty to ensure a smooth transition throughout the substrate. After the epoxy putty has cured, it is ground with an angle grinder, and then the substrate is cleaned, rolled coated, or painted with two layers of matching primer.