The basic treatment of car refurbishment mainly refers to the damage parts of the coating of various cars, such as the obvious discoloration of the appearance of the paint film. Coating defects such as peeling, chalking (discoloration), rust, cracks, loss of gloss or dullness. Because the paint film is too dilapidated and the decoration is poor, if it is not refurbished in time, it will seriously affect the appearance of the car and give people an uncivilized feeling. According to the actual situation of this type of car, the basic treatment should usually be divided into four steps: car washing, removing old paint, polishing, blowing and cleaning.
(1) Car wash
Car washing should use various car washing methods according to different types of cars. For example, for various passenger cars, because the car body is relatively high, it should be washed from the upper part of the roof . After the upper part is rinsed, the inside of the car body is repeatedly washed with tap water. and fenders, etc., are rinsed repeatedly. When flushing, it is best to have two people cooperate, that is, one person holds a hose to flush, and the other uses a cloth mop to mop the dirt with the water flow. When washing the car, if there is a lot of grease on the surface of the old paint , you can add an appropriate amount of cleaning agent to the tap water, use a high-pressure water gun to clean the grease, and then use clean water to repeatedly rinse all parts inside and out. After each car is rinsed, remove the accumulated water at each corner with cotton gauze, and wipe off the water.
(2) Old paint
Generally, three methods can be used: scraping method, paint stripping method and mechanical tool removal method:
① scraping method
This method is mainly suitable for the removal of old paint before refurbishment of trucks and ordinary passenger cars . Tools such as steel spatulas and steel flat shovels can be used during operation. When removing the old paint of passenger cars, since the thick putty layer of ordinary passenger cars is mainly distributed in the four corners of the front and rear walls, the lower part of the windshield of the front wall, and the surfaces of the doors on both sides, these parts should be cracked, grained, loose, etc. Bad old coatings shall . Because the putty layer in these parts is prone to cracking, loosening or crystal grains and other undesirable phenomena when encountering vibrations caused by uneven road surfaces during the driving of the bus, especially the thicker water quality putty layer is more prone to the above phenomena when encountering severe vibrations, so These thick layers of putty must For the thin putty layer on other parts, if there are no cracks, crystal grains, bubbling and other adverse phenomena, and the adhesion is strong (strong), and the appearance of the paint film is intact, it is not necessary to remove it, so as to be used as the first step of new coating Coating, reducing the amount of material used for coating. But for the large surface of the car body on both sides, if there is rust on the surface of the old paint, it must cleaned with a steel shovel in turn, and the quality of the refurbishment painting should not be affected by saving trouble. When cleaning, use a steel shovel to stick to the surface of the object, and remove it with force to effectively clean it. When removing the old paint on the windows, front and rear windshields, etc., be careful not to use too much force to prevent steel shovel from damaging the glass.
When removing the old paint of the truck, since the original putty layer outside the cab is mostly oil-based putty, such as ester glue putty, phenolic putty, etc., the adhesion is strong. As long as there is no cracking or other adverse phenomena on the putty, it is not necessary to remove it. In order to serve as the bottom layer of the new coating . If the paint film produces rust, it is necessary to effectively remove the old paint film parts (except the putty layer) successively.
②Paint stripping method
That is to use the paint remover to remove the old paint in turn. It is mainly suitable for the side window pillars and windshield pillars of passenger cars, the windshield pillars of cars, the glass frame of the door and other parts that are not easy to remove with a spatula. When removing paint, first use a brush dipped in paint remover to continuously brush the surface of the old paint. When the old paint swells and wrinkles (bulges), use a duster to clean it in turn. Generally, each part should be repeated 2-3 times. It is easy to effectively clean the old paint. For the old acrylic polyurethane paint with strong adhesion after high-temperature baking, if the paint remover is ineffective, it can be used as the bottom layer of the new coating for ordinary passenger and truck vehicles without removing it . , you need to carefully remove it with tools such as steel shovels, so as not to affect the quality and decoration after the new painting .
③Mechanical tool removal method
The mechanical tool removal method is mainly suitable for the removal of old paint on various car surfaces. Because the parts of the car body are pressed and formed with a mold, each part has a curved shape and a smooth appearance, and usually the primer can be directly . If the old paint on these parts is removed with a steel shovel, the traces of the shovel will often show , which will affect the quality and appearance. However, after cleaning with mechanical tools, traces can be avoided, which is conducive to improving the quality of the refurbished coating . When removing the old paint, you can use No. 80-100 emery cloth first, and cover or stick the emery cloth to the grinding disc After the old paint is removed, the old paint of the whole car is completely removed, and then the 120-150 emery cloth is replaced to smooth the coarse sand marks on the surface of each part. This process is commonly known as too fine.
(3) polishing
After the old paint on the base surface of various refurbished cars is removed, it needs to be polished to make the surface free of residue and rust , and then blown and wiped. When polishing, it is necessary to use an appropriate method to polish .
For example, on the base of various ordinary and mid-range passenger cars, there are often obvious rust pits (raindrop-sized rust) after the old paint is removed, especially windows on both sides of the vehicle body and the lower surfaces of the front and rear windshields, which are often damaged by rain. Let the rainwater gradually infiltrate into the bottom layer , form rust over time, and cause rust pits on the surface of the steel plate, so it is necessary to remove the rust first , and then perform a full-scale polishing. - No. 70 coarse sand, that is, first use a steel brush to repeatedly brush the rusted part of the rust pit until the metallic luster is exposed, and then use an emery cloth to polish it completely. Especially for sundries such as putty traces left over from the old paint , it should be smoothed vigorously. The facets and edge surfaces of each part should also be carefully polished and smoothed in turn.
For the base of various cars, use No. 100-120 emery cloth to repeatedly polish the parts where the old paint has been removed, especially for the parts that have not been ground by the sander when removing the old paint, and do not miss it. For the electroplated parts on the surface of various cars, such as handle parts, electroplated lamp holders, electroplated beading, electroplated sign parts, etc., if prickly heat-like (star point) rust occurs do not polish with abrasive cloth to prevent damage to the coating. Rust, you can use a clean towel dipped in sand wax to remove the rust repeatedly, so that it will not damage the coating, but also protect the coating. For the base layer of various trucks, the outside of the cab can be polished with No. 120 emery cloth, and other parts can be polished . When grinding the plane parts, grind hard 5-6 back and forth for each part, and 2-3 back and forth for each other surface.
