Repair and painting technology
The result of work in auto repair depends not only on the choice of high-quality paint materials and the exact selection of paint shade. It is also important to properly prepare the surface for painting. If you carefully perform all the necessary stages of repair and painting in compliance with all technological recommendations and requirements, the result will be at a decent level.
Main stages of repair and painting of metal parts
Checking the coating before painting
All metal body parts are sold with a ground surface, which is commonly called "transportation ground". Many of them are covered with anti-corrosion primer applied using cataphoresis technology, which provides high strength and anti-corrosion characteristics of the coating. The strength and quality of the coating determine the solvent test: saturated with solvent cloth put on a detail for a few minutes, then hold her on the surface of the part, if the cloth turns the color of the soil, then this coverage is recommended to remove from surfaces.
High-quality preservation coating should not be washed off with a solvent.
At this mandatory and most important stage, remove dirt from the surface of the repaired part. Degreasing is performed before and after grinding. At the same time, sprayers are used to apply Reoflex anti-silicon to the surface and wipes to remove anti-silicon from the part. Instead of a sprayer, you can also use a napkin moistened with antisilicon.
Attention! It is necessary to exclude independent evaporation of antisilicon from the surface of the part!
The right choice of material for grinding is also one of the most important points. Grinding begins with abrasives with coarse grain and gradually reduces it. Recommendations for selecting abrasives are given in Table 1.
*In this case, the surface must be thoroughly dried before applying the enamel.
Before using, the putty is mixed with 2-3% of the hardener in a weight ratio.
Attention! If there is not enough hardener, the drying of the putty slows down, the grinding is worse and the abrasive "clogs", and if there is an excess amount of hardener in the putty, peroxide spots may appear on the paint coating.
Then putty up to 4 mm thick is applied to the prepared surface. Drying 30 minutes at +20°C. For additional leveling of a large area, use a sprayed reoflex putty.
The primer must be prepared in accordance with the ratios of the diluents and hardeners specified in the TDS before application. All sections that are ground to metal are covered with 1 layer of anticorrosive soil. The drying time of anticorrosive soils is shown in Table 2.
After drying, the levelling primer is applied in 2-3 layers with a thickness of 130-250 microns. Exposure time between layers is 10-15 minutes (until matte). For application, use a pneumatic gun with a nozzle of 1.6-1.8 mm, a pressure of 2-4 bar (depending on the type of gun). Drying is performed at a temperature of + 20°C for 4-8 hours (depending on the number of layers and thickness of the coating) or at +60°C for 30 minutes. Before applying the enamel, the primer-Leveller is ground with abrasives P320 - P500.
Note. If Reoflex epoxy primer is used as an anticorrosive and leveling primer, then applying a leveling primer to it can be excluded.
The application of acrylic enamel
Before applying, the acrylic enamel must be prepared according to TDS. For applying acrylic enamels, paint guns with a nozzle of 1.3-1.5 mm, a pressure of 2-4 bar (depending on the type of spray gun) are used. Enamels are applied in 2-3 layers with an exposure time between layers of 10 minutes at +20°C. Air drying of acrylic enamels is 16 hours at +20°C or 30 minutes at +60°C. Before forced drying, it is necessary to make an exposure of 10 minutes at +20°C. After drying, the painted surface may require polishing to eliminate such defects as streaks, large shagreen, weeds, etc.
The application of the base enamel
Before applying, the base enamel must also be prepared according to TDS. For applying the base enamel, paint guns with a nozzle of 1.3-1.5 mm, a pressure of 2-4 bar (depending on the type of spray gun) are used. Base enamels are applied in 2-3 layers with an exposure time between layers of 10 minutes at +20°C. Before applying the varnish, it is necessary to wait until the surface is completely opaque (usually 10-15 minutes are enough, but no more than 24 hours). This is extremely necessary, because applying acrylic varnish to the base enamel that is not dry can lead to a decrease or complete loss of adhesion between the varnish and the base enamel, as a result, the varnish may detach from the enamel. After the base enamel has dried, it is recommended to wipe the painted surface with a sticky cloth.
The application of acrylic paints
Before applying the acrylic varnish is also prepared according to TDS. For application, use paint guns with a nozzle size of 1.3-1.5 mm at a pressure of 2-4 bar (depending on the type of spray gun). Acrylic lacquers are applied in 1.5-2 layers, depending on the type of material. In the case of applying the varnish in 2 layers, the exposure between the layers is made for 10 minutes at 20°C, with a half-layer application, exposure is not required. The final type of coating can be predicted by adjusting the application parameters: the method of preparing the material, the distance to the surface to be painted, the settings of the spray gun, the ambient temperature, and so on.
"Wet on wet" - a method of painting in which the paint material is applied without completely drying and grinding the previous layer. In this method, only one grinding operation is performed - at the very beginning. Each subsequent layer is applied without intermediate sanding, which significantly reduces the repair time. But if the soil is applied with a large shagreen or a large amount of "garbage", it must be dried and sanded. When painting using the wet-on-wet method, the requirements for compliance with minimum weeds, temperature conditions and other basic conditions must be the highest.
The method of "wet on wet" with the use of anti-rust primer
This method is used when during the grinding process on the edges and other surfaces of complex shapes, the transport soil is "rubbed" to the metal. Since the layer of transport soil often does not exceed 15-20 microns, it is quite difficult to avoid this. At the same time, an anti-corrosion primer is applied to the prepared and cleaned surface of the repaired part according to TDS. An anti-corrosion primer is applied to the anti-corrosion primer according to TDS. Then the final coating is applied (acrylic enamel or base-varnish system).
The method of "wet on wet" without the use of anticorrosive primer
Anticorrosive soil can not be used in the case when after careful grinding of the "transport" soil there are no places to "wipe" to the metal. In this case, the prepared and cleaned surface of the repaired part is applied with the Reoflex leveling primer according to TDS. Then the final coating is applied (acrylic enamel or base-varnish system).
Note. After drying, the painted surface may require polishing to eliminate such defects as streaks, large shagreen, weeds, etc.
Smooth transition method
This method of painting is used depending on the damage, both within one element and with the color of the neighboring one. It is used mainly to reduce the color differences between the repaired parts and the original ones, and in some cases to minimize costs.
Smooth transition painting using base enamel and varnish
To prepare the repaired surface, the area of the part adjacent to the repaired area is matted. If the transition is not planned for the varnish, then the entire element is matted. To do this, use an abrasive P400-P500 (or P800 - P1000 in the case of water). We recommend using a matting paste with a small amount of water. When matting, special attention is paid to the ends and hard-to-reach places, because their poor-quality processing in the future can lead to peeling and chipping of the coating. After processing, the surface is blown with compressed air. When using matting paste, the remaining paste is removed using water. Then degrease with Reoflex antisilicon and wipe with a sticky cloth.
The next step to create a wet substrate is to apply the base for Reoflex transitions in 1 layer to the sealed zone (the material does not require dilution). The surface is kept for 3-5 minutes at a temperature of + 20°C. Then, without waiting for complete drying, the base enamel is applied to the repaired area in 2-3 layers diagonally. It is not recommended to spray the transition in a single vertical line, because in this case, the transition will be noticeable. When applying enamel, it is necessary to gradually expand the color zone, i.e. each subsequent layer of enamel should overlap the previous one. Interlayer drying is performed within 10 minutes at a temperature of + 20°C. Before applying each layer, it is recommended to wipe the surface with a sticky cloth. After drying the enamel to a matte state (15 minutes at a temperature of +20°C), apply the varnish in compliance with TDS requirements.
In the event that there is a need to go over the varnish, The painted surface is applied reoflex varnish in 2 layers, gradually expanding the color zone, similar to applying the base enamel. The varnish is applied in strict accordance with TDS. After applying the varnish and a slight exposure to the transition zone, apply the Reoflex transition thinner in 1 layer. The transition thinner is a ready-to-use product, but if necessary it can be mixed with a ready-made mixture of acrylic varnish in a ratio of 5 to 1 by volume. Drying is performed in strict accordance with TDS for acrylic lacquers. After the coating is completely dry, if necessary, the transition zone can be polished.
Smooth transition paint with acrylic enamel
When using this method, the finished acrylic enamel is applied to the prepared repaired area in 2-3 layers diagonally. It is not recommended to spray the transition in a single vertical line, because in this case the transition will be noticeable. When applying enamel, the color zone is gradually expanded, i.e. each subsequent layer of enamel should overlap the previous one. Interlayer drying is performed in strict accordance with TDS for acrylic enamels. After a slight exposure, a 1-layer Reoflex transition thinner is applied to the transition zone of the painted surface.
Note. After the painted surface has dried, it may require polishing to eliminate such defects as streaks, large shagreen, weeds, etc.
Features of repair and painting of plastic parts
When working with plastic parts, the algorithm is the same as when working with metal parts. As with metal parts, new plastic parts may have an unsatisfactory ground coating that should be removed before painting (see the "section about metal"for a solvent test). Most of the new plastic parts can be supplied uncoated. To paint a plastic part that does not require repair, it is necessary to sand its surface with an abrasive P400-P600 or a matting cloth of gray color. If there is no primer coating on the part, or if there is a primer coating on the part, but with " wipes” to the plastic, then the next step is to apply an adhesive
When working with a plastic part in need of repair, special materials are used:
- putty for bumpers and / or putty with carbon fiber;
- soil for plastic 5 + 1;
- polyester resin and glass mat.
For the final leveling of the surface, you can use any acrylic
soils subject to their plasticization.
Before using the materials, carefully study the information on the bank and TDS. Do not use
material or mixture with expired pot life, do not try to further dilute the thickened
material. Close cans of material tightly as many of them react with moisture in the air and
lose their working properties. Carefully observe the recommended number of coats when applying
materials, mixing ratio, application distance, nozzle size, application pressure and drying time.