Restoration of the appearance and protective properties of the body from aluminum-alloy Unlike steel, aluminum does not rust as we know it, but is susceptible to oxidation and electrochemical destruction when it comes into contact with salt water or vagus currents. The right painting technology creates a robust barrier that extends the life of a vessel for decades.
Many owners underestimate the complexity of working with the duraluminium or AMGIt's a fatal mistake, because it doesn't have any specific preparation and chemically active primers The coating will defuse in the first season, requiring strict sequences of operations, from degreasing to finishing polishing, and the use of specialized materials compatible with non-ferrous metals.
The quality of the final result depends on how carefully the surface preparation was carried out, even microscopic residues of fat or oxide film can become centers of the beginning of detachment of the paint material. solvent Abrasive materials should be approached with maximum responsibility, without saving on consumables.
paint selection materials for aluminum
The first and most critical step is to select the chemistry, aluminum is a group of non-ferrous metals that require special adhesion conditions, standard alkyd enamel, popular in household construction, on the hull of the boat will not last long. epoxy or polyurethane compounds that have high elasticity and chemical resistance.
Special attention should be paid to the primer layer. zinc-filled soil Or special primers with chromates (although they are becoming rare due to environmental regulations), which create a passivating layer that prevents the development of film corrosion, and if you plan to use a boat in salt water, you can't save on the ground.
⚠️ Warning: Never use copper-containing antifouling paints on an aluminum case without a special insulating layer. The contact of copper and aluminum in the electrolyte (water) creates a galvanic pair, which will lead to rapid destruction of the metal of the case.
The finishing should also be in line with the operating conditions. For slow-moving pleasure boats, acrylic polyurethanes are suitable, which give excellent gloss. For high-speed boats experiencing shock loads from waves, it is better to choose more viscous ones. epoxyIt is important that the solvent in the paint is not too aggressive for the already applied soil, otherwise there will be a “curling” effect of the layers.
Tools and workplace preparation
You can't paint well without the right equipment. You can work in a garage or outdoors, you can use not only a set of brushes and rollers, but also a process mechanization tool. You can ideally use a compressor and a spray gun, but you can also use high-quality work for small volumes. velour-roller with a short pile.
Surface preparation is 80 percent of the success of the whole operation. You'll need a grinder (orbital or vibrational) with a set of abrasives of different grains, start with a large grain (P80-P120) to remove the old coating and oxides, and finish with a small one (P240-P320) to create adhesion-producing rics.
Don't forget personal protective equipment. Solvent vapors and aluminum grinding dust are bad for your health. Be sure to use a charcoal filter respirator, safety glasses and gloves. The workplace should be well ventilated but protected from dust and direct sunlight, which can dry the solvent in the paint too quickly.
- 🛠️ Grinding machine and sandpaper with grain from P80 to P400.
- 🧪 Degreasing agent (white spirit, acetone or specialized formulations).
- 🎨 Krascopult with a diameter of duse 1.4-1.6 mm or high-quality brushes.
- 🧤 Protective equipment: respirator, glasses, gloves, overalls.
Technology of cleaning and degreasing of the body
The preparation process begins with a thorough inspection of the case, all deep dents and cracks must be brewed or sealed before the painting begins. The old coating, if it is held tight and not bloated, you can not remove completely, just wrap it to a matte state. mechanical sweep metal is required.
After machining, the chemical preparation process takes place. Aluminum is instantly coated with a thin oxide film that interferes with adhesion. Orthophosphoric acid rust converters are acceptable, but require careful neutralization and washing with water. A more modern method is the use of orthophosphoric acid rust converters. grass-block (wash primer) that chemically bind to metal.
The Secret to Perfect Adhesion
After grinding and before primer, warm the body with a building hair dryer to a temperature of 30-40 degrees. This will remove moisture from the metal microcracks and improve the spreading of the soil.
Degreasing is the final step before painting. Rub the surface with a rag soaked in a solvent. The movements must be progressive so that the dirt is not smeared, but collected. Once the solvent is dry, you can no longer touch the surface with your gloves, because the skin fat will worsen the adhesion of the paint.
Coating sequence
The process of painting is highly regulated and requires time intervals. soilIt's designed to provide adhesion and corrosion protection, and it's applied in a thin layer to avoid sweating, and it's drying time depends on the air temperature and the type of material, usually 2 to 24 hours.
Once the first layer is dry, interlayer grinding is often required, which removes the shagrens and creates roughness for the next layer. If you use two-layer soil, you need to grind it carefully so you don't rub it to the metal, then you apply a second layer of soil or immediately finish enamel, if the material technology allows.
☑️ Checklist before painting
Finish enamel is applied in 2-3 layers. Each subsequent layer is applied after drying the previous one "on the stick." It is important to follow the technique of "wet by wet" or interlayer grinding, depending on the recommendations of the paint manufacturer. The dry layer should be thick enough to create a solid film, but not excessively so that the coating does not lose elasticity.
Material compatibility table and drying time
For ease of planning, it is important to know the specifications of the materials used. Below is a comparative table of popular types of coatings for aluminum boats. Note that drying time is indicated for standard conditions (+20 ° C), at lower temperatures it increases by 1.5-2 times.
| Type of material | Basis | Drying time (layer) | Resistance to water | Difficulty of application |
|---|---|---|---|---|
| GF enamel | Alkyd | 24 hours. | Low. | Low. |
| EP enamel | epoxy | 4-6 hours | High. | Medium |
| Polyurethane | 2K Polyurethane | 6-8 hours | Very high. | High. |
| acrylic | Acrylic | 2-3 hours | Medium | Low. |
And you can see from the table that epoxy and polyurethane compounds are better at performance, but they require more precise mixing ratios. A hardener dosage error can cause the paint to either not dry or become brittle and crack.
When mixing two-component paints, use only dividing containers. It is impossible to determine a ratio of 4:1 or 10:1 on the eye, and this depends on the strength of the coating.
Common mistakes and defects in painting
Even skilled craftsmen sometimes make mistakes that nullify all efforts. bubble This is often due to poor degreasing or moisture getting under the paint layer, and it can also be caused by too rapid drying of the solvent at high body temperature.
Another common problem is shaven (orange peel), which occurs when the paint is too thick or applied under too high a spray gun pressure, and this defect can only be corrected after drying completely by grinding and polishing, which is time-consuming. To avoid this, strictly follow the instructions for diluting the material.
⚠️ Warning: Do not attempt to accelerate drying with powerful heat guns. Sharp heating of freshly painted surfaces leads to boiling of solvent inside the layer and formation of irreversible defects.
Separation of paint layers is a sign of the use of incompatible materials (for example, applying epoxy paint on old oil without insulation) or insufficient surface roughness. If the paint began to peel after a year, the preparation technology was most likely violated or poor-quality soil was used.
Coverage care and recovery
After drying, the paint gains its final strength within 7-14 days, during which time it is not recommended to launch the boat into the water or subjected it to mechanical stress, regular care consists of washing with fresh water after each release to salt water and periodic treatment with polyroles to restore the gloss.
Small chips and scratches must be painted immediately, without waiting for the corrosion process to begin, it is convenient to have a small supply of paint preserved in sealed containers. Local repair is carried out using the same technology: stripping, degreasing, soil, paint.
The durability of painting an aluminum boat depends on the quality of surface preparation and only 30% on the cost of the paint itself.
The use of paint technology allows you to obtain a coating that will protect the aluminum hull for 5-10 years or more, an investment in the safety and aesthetics of your vessel, which pays off without the need for frequent repairs and loss of speed due to fouling of the bottom.
Can I paint an aluminum boat with a regular spray enamel?
Technically, it can, but it will last for a season, and aerosol paints do not have the adhesion to aluminum and resistance to UV and water, and for temporary cosmetic effects, it is acceptable, but for full protection, it requires the use of specialized boat enamels.
Do I need to remove the engine and equipment before painting?
It is advisable to remove all removable elements: liners, rundooks, naktouse, which will allow you to properly paint hard-to-reach places under them and avoid leaks on chrome parts. The engine can not be removed, but it must be carefully closed with paint tape and film.
What is the best temperature for painting a boat?
The optimum temperature range for most marine paints is from +15°C to +25°C at a humidity of no more than 80%. At lower temperatures, the chemical reactions of polymerization slow down or stop, and at high temperatures, the paint dries too quickly without having time to spread.
How to remove the paint leaks if they are already dry?
The dried streams are carefully cut with a sharp blade or sanded with a P1000-P1500 abrasive to the level of the main coating, then the place is grinded by P2000 and polished with polishing paste. If the flow is deep, local coloring may be required.