4 compositions for painting aluminum and rules to apply at home
Aluminum is a difficult material to paint. Its smooth surface does not adhere well to paint. Therefore, light metal is painted using special technologies. Compositions for painting aluminum profiles should have increased adhesion. When working with paints on aluminum at home, it is important to follow the application instructions and prepare the surface well, otherwise the coating will quickly lose its aesthetic appearance.
Hardware Features
On the surface of aluminum, like any metal, an oxide film forms. On aluminum, it has the following characteristics:
- the surface is covered with a thicker layer than on other metals, regardless of the processing method and environmental conditions;
- the film prevents moisture from penetrating the surface, so that water-based paints do not stick to aluminum;
- oil paint also flakes - slower from smooth parts, faster from curly parts.
The surface particles of the material come into contact with oxygen from the atmosphere. As a result, aluminum oxide is formed, covering the product with a dense layer.The metal seems powdered with white dust and slightly rough to the touch.
Requirements for coloring compositions
Aluminum is used in the manufacture of front, articulated structures, engine parts, vehicle casings. Products are destroyed by precipitation and ultraviolet radiation. Therefore, the requirements for paints for outdoor use are the highest: resistance to mechanical damage, constant exposure to moisture and temperature changes.
Aluminum is also used in shipbuilding. The oxide film serves as a good anti-corrosion coating, but if its integrity is violated, the paint should perform the protective function. Therefore, the coating for aluminum boats must provide reliable protection against mold and algae. In technical rooms with a high concentration of vapor, aluminum without an oxide film is quickly destroyed. The paint should prevent fumes from reaching the metal.
Varieties of paints suitable for painting
There are four types of aluminum paints that meet the requirements to varying degrees. Coatings have their own advantages and disadvantages, therefore, when choosing, you should take into account the purpose of the room to be painted.
Aniline
The main area of application of aniline dyes is the textile industry. They are available in powder and liquid form.
Aniline is a toxic substance, but after drying the product is harmless to health.
Epoxy
Resins form the strongest bonds.
Durable epoxy paints are usually made up of two components, a base formulation and a volatile curing agent.
Acrylic
The base of the paint is a polymer that firmly adheres to the surface.
Spray paints are distinguished by their ease of use. The spray can be used to paint hard-to-reach corners and small parts. In addition, acrylic paints are more varied in color. White compositions can be colored.
Powder
Also, the advantage of powder coating is the absence of toxic release of the composition or of the solvent, more economical consumption. Most often, to fix the dye, the parts are subjected to heat treatment in a special thermal installation, so the technology cannot be replicated at home.
home painting instructions
Besides choosing a durable paint, the method of coloring the aluminum is also important. There are three main methods for painting a specific metal. The most durable result is achieved after anodizing - keeping the part in a live electrolyte solution.
Anodizing technology
To increase the adhesion of aluminum, you will need:
- salt or soda;
- distilled water;
- glass and aluminum basin;
- fine grain emery;
- battery with a current intensity of 2 amperes and a voltage of 12 volts;
- electrodes;
- acetone.
Surface preparation:
- prepare a concentrated solution of salt or soda in different dishes;
- insist the concentrate for 15 minutes and strain;
- mix in a glass container one part of the solution with nine parts of water;
- sand the aluminum part with emery;
- degrease with acetone;
- rinse with water;
- do not touch the washed part with your hands so that the stains do not remain;
- soak in each solution in turn for 30 minutes;
- connect the anode to the part, the cathode to the container, connect the electrodes to the battery;
- give tension for 1.5-2 hours.
To prepare the coloring composition you will need:
- 15 grams of aniline dye;
- 1 milliliter of acetic acid;
- liter of water.
How to paint a room:
- mix dye and acid in water;
- heat up to 80 degrees;
- lower the prepared aluminum part into the mixture;
- get it in 15 minutes.
For intensive staining, the part is held in solution longer, and for light staining - less.
The color of anodized aluminum can be changed by maintaining the product in chemical solutions. How to cook them and achieve a certain shade is shown in the following table:
| Option 1 | Option 2 | Color | ||
| salt name | Dosage in grams per liter of water | salt name | Dosage in grams per liter of water | |
| Potassium hexacio-(II) ferrate | 10-50 | Iron (III) chloride | 10-100 | Blue, light blue |
| Potassium hexacio-(II) ferrate | 50-100 | Copper (II) sulfate | 10-100 | brown |
| Potassium dichromate | 50-100 | lead acetate | 100-200 | YELLOW |
| Potassium chromate | 5-10 | Silver nitrate | 50-100 | Orange |
| Barium chloride | 10-50 | sodium sulphate | 10-50 | white |
| cobalt acetate | 50-100 | potassium permanganate | 25-30 | Black |
The part is maintained alternately in the first and the second solution for 30 minutes, then washed with distilled water.
Powder coating
Powder dyes harden at high temperatures. Therefore, a baking oven is required for coloring. In this case, the part must be absolutely clean.
How to properly prepare the surface:
- clean old paint with solvent;
- fine emery sand;
- degrease with alcohol;
- rinse with water;
- treat with alkaline and acidic solutions;
- wash off traces of alkalis with distilled water.
Painting is carried out in two ways:
- ionized gun;
- pastry shop.
For the first method, the part is grounded. Using a gun, an electric shock is applied to the powder particles and these are attracted to the aluminum surface. Industrial heat chambers are used for paint baking. Both methods of powder coating require special skills and equipment.
Painting with primers and special enamels
The method consists of applying the compositions to aluminum without electrical treatment.
For coloring you will need:
- primer on aluminum, stainless steel or chrome;
- fine grit sandpaper;
- zinc-aluminum paint for metal;
- acetone or white spirit.
How to prepare a room:
- clean the surface with sandpaper;
- treat with acetone or white spirit;
- apply a primer in one layer;
- after 5 minutes, apply a second coat.
To paint over a primer, it is best to use spray paint.The dye should be sprayed upwards from a distance of 30 centimeters. The second layer can be covered after 20 minutes. 3-4 coats are applied for added strength.
The piece is completely dry after 6 hours. In addition, varnishing will help strengthen the coating. Automotive varnish is suitable for fixing.
Tips and Warnings
How to properly paint aluminum so that it does not peel off:
- emery-cleaned metal should not be left exposed. From a reaction with oxygen, the part will oxidize, and the soil will not be sampled. The work will have to start over. Therefore, after sanding and degreasing, you should immediately start priming;
- if the spray bottle is clogged, you need to shake the bottle and spray the paint on the rough surface until the layer is evenly laid;
- suitable fraction of sandpaper for sanding - 600, 800 and 1200;
- an aluminum window profile is sanded with 500 fractions of emery, primed and painted with a spray gun, and the glass is previously wiped with alcohol and glued with adhesive tape to a polyethylene film;
- automotive spray paint is suitable for painting aluminum profiles in sliding furniture;
- the old aluminum boat coating can be removed with a grinder or a washer, it can be painted with a roller or a spray gun. For painting the bottom, it is better to use epoxy compounds;
- proven Hammerite specialty paint. It is a durable anti-corrosion coating that can be applied over rust without a primer. But it requires a solvent from the same manufacturer, which is difficult to find in the market.
Safety precautions for home aluminum paint:
- work in a ventilated place;
- before painting, clean with water so that dust does not settle on the parts and does not mix with the paint;
- do not paint near heat sources - next to a radiator, stove, in direct sunlight;
- remove chemicals, gas cans, medical solutions, household chemicals from the work area;
- use lamps for lighting.
It is necessary to work with powder dye in protective clothing:
- tight medical gown;
- gas mask or respirator with goggles;
- gloves.
During painting, it is important to maintain cleanliness: thoroughly clean the surface of dust after sanding, avoid drips and drips of paint, when working in a garage or shed, make sure that midges do not enter not in composition. Coating on a flat surface lasts longer.