The appearance of aquatic equipment is not only a matter of aesthetics, but also an important aspect of protecting expensive equipment from an aggressive environment: salt, fresh water, ultraviolet light and mechanical damage can quickly turn shiny metal into a rusty pile if not taken in time. Painting of the outboard motor is the most affordable and effective way to extend the life of the unit, preserving its functionality and presentation.
The process of refining paint requires careful preparation and compliance with technological nuances. Many owners mistakenly believe that it is enough to simply apply a layer of paint on top of old chips, but this saving of time will only lead to the rapid peeling of the new coating. Aluminum alloyswhich are used in most of the silk, and stainless steel They require an individual approach to materials adhesion.
In this article, we will take a look at all the steps from chemical selection to finish polishing, which tools are really needed and what you can save on without losing quality, and the work done well will allow you to forget about corrosion for several seasons of active use.
Choosing the Right Type of Paint for lower unit
The first and most critical step is to find the right paint material, and conventional car enamels or nitro paints are not suitable for use in aquatic environments, as they do not have the necessary elasticity and chemical resistance. Alkyd paints They may seem attractive in price, but they quickly lose color and crack under the influence of salt water and solar radiation.
The best choice for remediation of the coating are specialized formulations based on polyurethane or epoxyThese materials create a strong, inert film that keeps moisture and oxygen out of the metal. Interlux Brightside or Nautic PaintThey have high glossiness and resistance to abrasion, which is especially important for the lower part of the engine.
It is also worth considering two-component systems that require mixing the base with a hardener immediately before application. Two-component polyurethane paints They provide maximum chemical and mechanical strength comparable to the factory coating, but require very precise compliance with mixing proportions.
When choosing a color, consider that dark colors (black, dark blue) are heated more in the sun, which can accelerate the aging of seals at the top of the lower unit.
It is important to pay attention to the compatibility of the paint with the base material. Aluminum alloys often require special soils-insulators to prevent oxidation. If you plan to use the motor in salt water, make sure that the paint chosen has a label of resistance to the marine environment.
Required tools and materials for the job
The quality of the final result depends on how well you have prepared the workplace and tools. You should not start working on your knee in a garage full of things, because dust is the main enemy of glossy surfaces. You need a spacious, well-ventilated room with a temperature of at least 15 ° C and humidity of up to 70%.
The machining of the surface will require a set of abrasive materials of different grains, sandpaper must be fabric or paper based with moisture-resistant coating, the use of power tools such as: squirt-strinderIt will significantly speed up the process, but requires skill to avoid leaving circular drawings on the metal.
- 🛠️ Abrasive materials: sandpaper with grains P80, P240, P400, P800 and P1200, as well as grinding sponges for hard-to-reach places.
- 🧴 Chemistry: degreasing agent (antisilicone), rust converter (if there are foci of corrosion), primer for aluminum, selected enamel and solvent.
- 🖌️ Depositing tools: spray gun (compressor or aerosol cylinder with adapter), brushes for coloring small defects, paint tape and covering material.
Pay special attention to personal protective equipment. Solvents and paints are toxic, so the presence of high-quality products. respiratory You'll also need protective glasses and nitrile gloves that are resistant to chemicals.
☑️ Preparation for painting
Technology of surface preparation for painting
The surface preparation takes up to 80 percent of the time, and it's what determines how long the new coating lasts, and the first task is to completely remove the old, damaged paintwork and all the corrosion points, and if you just paint it, it will continue to develop under the new paint layer, causing swelling.
Chemical washes or mechanical methods can be used to remove deep defects and old paint. Mechanical stripping to metal is the most reliable way. Use a P80-P120 abrasive to remove the main layer, gradually moving to a finer grain. The surface should become matte and rough to ensure maximum adhesion.
⚠️ Attention: When grinding aluminum alloys, don't use steel wire or steel brushes. The iron particles left in the aluminum pores will immediately rust, leaving ugly streams. Use only brass brushes or abrasive materials.
After machining, you need to carefully degrease the surface. Use special degreasing agents or isopropyl alcohol. Rub the surface with a lilac-free wipe, changing it as it becomes dirty. It is important not to touch the prepared surface with your hands, as the skin fat will worsen the adhesion of the soil.
If you find deep scratches or shells from corrosion, you need to fill them up. Use a metal epoxy putty designed for wet environments. Once dry, the putty is ground level with the main surface, creating a perfectly smooth plane.
Printing and coating
Soiling is the foundation of your future coating. Outboard Motors use special etching soils (wash primer) or epoxy soils. Eating soil contains acid that micro-grazes the surface of aluminum, providing chemical adhesion. Epoxy soil creates a powerful barrier film.
The soil should be applied in thin layers, avoiding ducts. Usually 1-2 layers are enough. After drying the soil (time indicated on the can by the manufacturer), it should be slightly slapped with the abrasive P400-P600 to remove dust and shafts, which will provide an ideal base for the finishing enamel.
Finishing paint requires accuracy and adhering to the spraying distance. The spray is kept perpendicular to the surface at a distance of 20-25 cm Movements should be smooth, with a torch overlap by 50%. The first layer is made thin ("fog"), so that the paint is grasped, and the subsequent - more saturated.
- 🎨 First layer: It is applied thinly, serves for clutch, can look translucent.
- 🎨 Second layer: It is applied after 15-20 minutes (according to the instructions), gives the main color and cover.
- 🎨 Third layer: (optional) to obtain deep gloss and surface alignment.
Secrets of working with two-component paints
The viability of mixed two-part paint is limited to 2-4 hours. After that time, the paint in the jar will thicken and become unusable. Mix as much as you can produce at a time. The residues in the jar will harden into a monolith that can not be removed.
Between the layers, be sure to keep the interlayer drying. If you apply the next layer too early, the solvent may remain in the lower layers, which will lead to clouding or wrinkling of the coating ("orange peel").
Comparison of paint specifications for motors
To make a final decision on the choice of material, it is worth comparing the main specifications of popular coating types. Other operating conditions dictate their requirements for protective properties.
| Type of paint | Resistance to salt | Resistance to UV | Difficulty of application | Term of service |
|---|---|---|---|---|
| alkyd enamel | Low. | Medium | Low. | 1 season |
| Acrylic (aerosol) | Medium | High. | Low. | 1-2 seasons |
| Polyurethane (1K) | High. | Very high. | Medium | 3-4 |
| Polyurethane (2K) | Maximum | Maximum | High. | 5+ seasons |
As you can see from the table, material savings are often sideways in the case of outboard motors, and dual-component systems, despite their high cost and complexity, are more profitable in terms of life.
It is also worth considering that some engine manufacturers use special heat-resistant paints for the upper parts of the lower unit (muffler), as the temperature there can reach high values.
Drying, polishing and assembly of the unit
After the finishing layer is applied, the polymerization process begins, and although the paint may appear dry to the touch after an hour, the full chemical strength is gained within 7-14 days, during which time it is not recommended to operate the motor, especially in salt water, or to expose it to mechanical stress.
To achieve the perfect gloss after drying completely (after a few days), the surface can be polished. Use a soft-circle polisher and a fresh paint polisher to remove the fine shafts and dust that have been caught in the painting process.
⚠️ Warning: Do not use aggressive abrasive polishes immediately after painting. Let the coating gain hardness for at least 2 weeks. Otherwise, you can wipe the fresh paint to the ground.
When assembling the motor, be careful with fasteners. Bolts and nuts should be replaced with new galvanized ones or treated with graphite lubrication so that they do not boil in the future. Install the motor on the transom only after you are sure that all layers are completely dry.
Regular maintenance of the updated coating will prolong its life. After each salt water laying, the engine must be washed with fresh water. Once a season, it is recommended to apply a protective wax compound for boats, which will create an additional hydrophobic layer.
High-quality painting of the outboard motor is an investment in the durability of the equipment. Properly selected two-component polyurethane and careful surface preparation allow you to forget about corrosion for 5 years or more.
Can I paint my engine without taking it off the boat?
Theoretically, it can, but it's not recommended, the surface preparation will be low, the risk of paint getting on the boat and into the water, and it's also difficult to ensure that the spraying and the control of the stains in the vertical position is uniform without dismantling.
How much dried paint for outboard motors?
The drying time depends on the type of paint and temperature. Aerosol enamel dries "on a stick" in 30-60 minutes. Polyurethane two-component paints require 12-24 hours for primary polymerization and up to 14 days for full strength.
Do I need to remove the motor stickers before painting?
The original decals are best preserved if they are in good condition, carefully taped around the perimeter with paint tape, if damaged, removed, and then replaced with new ones or stenciled.
How to degrease the surface before painting?
It is best to use specialized degreasing agents (antisilicons) for auto repair or isopropyl alcohol. Gasoline, kerosene or white spirit can leave a greasy film that worsens adhesion.