The disguised shade, known as khaki, has long ceased to be the prerogative of exclusively military equipment and went far beyond camouflage tasks. In the modern care industry metallic This color is valued for its ability to hide dirt, dust and small surface defects better than glossy light or deep black tones. Emal khaki metal is not just a decorative coating, but a complex chemical composition that provides protection against corrosion, mechanical damage and aggressive environmental effects.
Choosing. alkyd-urethane With the pigment of khaki, owners of garages, car service stations and industrial facilities solve several tasks at once: prolong the service life of equipment, hide traces of operation and give objects a strict, functional appearance. Unlike standard black or gray soils, this shade allows you to create an aesthetic finish that does not require frequent updating.
In this article we will discuss in detail the chemical composition of such paints, the technology of their application to various types of metals and nuances, which are silent in construction stores. You will learn how to prepare a rusty surface and why phosphate It may be more important than the painting process.
Chemical composition and types of khaki enamels
The basis of any high-quality paint on metal determines its durability and adhesion. Alkyd enamel They remain the most popular choice due to their availability and ease of application, but for high load conditions they can be inferior to more modern analogues. They include alkyd resins, solvents and pigments, giving a characteristic greenish-brown hue.
The more durable option is epoxy and polyurethane compositions. They form a dense film on the metal surface that is resistant to impacts, scratches and chemical reagents such as gasoline or oil. It is such compositions are often used to paint the bottom of cars or machines in workshops.
It is important to distinguish paints by type of solvent. Water-soluble acrylic compounds are environmentally friendly and do not have a sharp smell, but require a perfectly dry surface and are often less resistant to abrasion compared to organ-soluble analogues.
- 🎨 Alkyd: Budgetary option for internal work or temporary protection.
- 🛡️ Epoxy: Maximum chemical resistance and adhesion to metal.
- 💧 Acrylic: They dry quickly, suitable for work in enclosed spaces.
- 🔥 Heat-resistant: They can withstand heating up to 600 ° C, suitable for exhaust systems.
⚠️ Attention: Do not mix paints on different bases (for example, alkyd with acrylic). This can lead to a chemical reaction, clotting of the composition and complete detachment of the coating after a short time.
The secret to khaki color persistence
Pigments used to produce the color of khaki (iron oxides, chromium), in themselves have high cover and light resistance. This means that even with partial burnout or abrasion of the upper layer, the color does not change dramatically, unlike bright blue or red shades, which quickly pale under ultraviolet light.
Preparation of metal surface: critical stage
The success of painting 80% depends on the quality of preparation of the base. Metal The material is capricious, and any remaining rust or fat particles under the paint layer will become a hotbed of new corrosion that will bulge the coating from the inside. The first step should always be mechanical cleaning.
Use a petal-disc angular grinding machine or metal brushes to remove loose rust and old flaking coating. After mechanical cleaning, the surface must be degreased. For this, solvents of the type are ideally suited White Spirit, nephras Or specialized antisilicones.
If deep corrosive ulcers are present on the metal, a simple clean-up is not enough. Application required rust-converter Orthophosphoric acid. They chemically convert iron oxide into a stable compound, creating a protective layer.
☑️ Checklist for metal preparation
Particular attention should be paid to drying after degreasing. Moisture remaining in the microcracks will lead to rapid muniation (bubbles) after applying enamel. Ideally, between degreasing and priming should take no more than 2-4 hours, so that the metal does not have time to cover a new, invisible to the eye layer of oxides.
Printing: the foundation of durability of the coating
Soil is the link between bare metal and decorative enamel khaki. Without a high-quality coating, even the most expensive paint will not be able to provide reliable protection. For ferrous metals (steel, cast iron) it is critically important to use corrosion-proofing, containing zinc or phosphates.
There are two main approaches to squashing. The first is the use of a separate soil (GF-021, epoxy soils), which requires complete drying before painting. The second is the use of soil enamels "3 in 1", which contain a rust converter, soil and paint in one bottle. Although the 3-in-1 is convenient, for critical designs such as car bodywork or load-bearing elements, professionals recommend separate application.
| Type of soil | Basis | Drying time | Application |
|---|---|---|---|
| GF-021 | Alkyd | 24 hours. | Static constructions, fences |
| epoxy | Two-pronged | 2-4 hours | Body of the car, bottom, aggressive environment |
| Zinc-filled | Polyurethane/Epoxy | 1-2 hours | Maximum anticorrosion |
| Acid (Washington) | Polyvinyl butyl | 15-30 minutes | Adhesion to smooth metal (aluminum) |
When applying the soil, it is important to observe the thickness of the layer. Too thin a layer will not cover the pores of the metal, and too thick can flow or dry for a long time inside. The optimal thickness of one layer is 15-20 microns.
The soil must contrast with the color of the finish enamel (for example, be light gray under the khaki) to visually control the uniformity of the overlap and the absence of gaps.
Technology of applying enamel color khaki
The application of paint can be done with a brush, roller or spray gun. To get a professional result in large areas, such as garage doors or car body, airless spraying or pneumatic work spray-rot They are uncontested. They provide a uniform texture without stripes.
If you use a brush or roller, choose tools with natural or combined bristles that are resistant to solvents. Synthetic brushes can dissolve in the aggressive environment of alkyd enamels. Movements should be smooth, along the long side of the product to minimize traces of pile.
It is important to observe the temperature regime. Most metal enamels require air and surface temperatures from +5°C to +30°C. At low temperatures, the paint becomes viscous and lies unevenly, and at high temperatures it dries too quickly, forming a “spin” or bubbles.
- 🌡️ Temperature: strictly according to the manufacturer's instructions (usually +15...+25°C).
- 💨 Humidity: not more than 80%, otherwise it may be swelling or swelling.
- 🧥 Defense: The mandatory use of respirator and gloves.
⚠️ Attention: When working with nitro-enamels or acid soils in a confined space (garage, chamber), powerful forced ventilation is required. Solvent vapors are heavier than air and can cause suffocation or explosive concentrations.
The finish layer is applied only after the previous one is completely dry. The “stickyness” of the surface is a sign that the polymerization is not yet complete and the application of the new layer will lead to defects.
For the perfect khaki shade over a large area, mix all the cans of paint you buy in one large container before you start work. The difference in shades between batches of even one manufacturer can be noticeable when drying.
Drying and polymerization: patience for results
Many people mistakenly believe that if the paint “does not stick”, then it is dried. In fact, the process polymerization (final strength) in alkyd and epoxy formulations takes from 7 to 14 days. In the early days, the coating remains vulnerable to mechanical stress and chemistry.
Speed up the process can be with the help of infrared drying or placing the product in a warm, dry room. However, sharp heating (for example, a heat gun at point-blank range) is strictly prohibited - this will lead to boiling of the solvent inside the layer and the formation of craters.
Full operational load (installing machinery, contact with water or fuel) should be given only after the expiration of the period specified in the technical passport of the product. For automotive enamels, this period can be up to 30 days for complete chemical resistance.
The effect of drying on the stick versus complete polymerization
The surface may appear dry in 2-4 hours (drying to stick), but inside the layer there are chemical reactions of crosslinking polymer chains. If at this moment to apply the next layer or load the part, you can break the structure of the film, which will lead to a reduction in the service life of the coating at times.
Common Errors and How to Resolve Them
Even experienced painters face paint defects. One of the most frequent problems is quill (Orange peel effect). It occurs due to too thick paint, high pressure in the spray gun or draft, which quickly cools the spray torch.
Subductions (floods) are the result of applying a too thick layer or insufficient exposure between the layers. Remove the stain can only be after complete polymerization: it is carefully sanded with abrasive P2000, polished and applied locally a layer of varnish or paint.
Separation "stocking" most often indicates poor degreasing or the presence of silicone on the surface (for example, from polishes). In this case, only complete removal of the coating, repeated cleaning and degreasing with special anti-silicone formulations helps.
- 📉 Matte spots: High humidity or ingress of moisture into the paint.
- 💥 Craters: The presence of oil or fat on the surface of the metal.
- 🌫️ Blunt-blue: condensation of moisture in the paint layer due to a sharp temperature drop.
Can I paint khaki metal over old paint?
Yes, you can, but only if the old coating is firmly held. It is necessary to check the adhesion (for example, a scotch test), clean the surface to matteness with an abrasive and degrease. If the old paint is grinded or peeled off, it must be removed completely.
What is the consumption of khaki paint per 1 square meter?
The average consumption of alkyd enamel is 100-150 grams per 1 m2 when applied in one layer. However, the actual flow rate depends on the roughness of the metal, the method of application and the color of the substrate. For rusty or rough metal consumption can increase by 1.5-2 times.
How do you dilute thickened paint?
Use only the solvent recommended by the manufacturer for a particular type of enamel (usually indicated on the can). For alkyd - White-spirite, solvent; for acrylic - water or a special acrylic diluent. Add the solvent should be in small portions (5-10%) and thoroughly mixed.