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Gates or water pipes coated with a layer of water-based emulsion or oil paint look neat and presentable. Suspensions perform both a decorative and protective function, preventing rust. But metal surfaces are regularly contacted with oxygen, which triggers chemical reactions that destroy the paint film. It loses anti-corrosion properties, and you have to remove the old cracked layer.
Precautions and a simple method
Some metal products are quite fragile, so they can not be treated with a blowtorch or cleaned with abrasive components. Others can handle hard brushes, sandpaper, and even a building hair dryer. The method of removing the protective suspension is selected depending on the thickness and composition of the base, as well as the type of paint itself.
The most economical way is mechanical. You will need a stiff stainless steel spatula or a kitchen knife. The main thing is that the tool has a sharp blade.
The painted surface is carefully inspected and a weak spot is found where the coating is swollen or cracked. The protective layer is tampered with the selected tool and removed, trying to grab rust, if any.
The second stage of the mechanical method is grinding. It is necessary to arm yourself with coarse sandpaper with water-repellent properties. If you take a simple variety, it will quickly erase and become unusable.
The workpiece is fixed on a bar made of hard plastic or wood, so that it is more convenient to grind the metal and level it. The base, which is treated with sandpaper, moistened with cold water. It is advisable to use a spray gun so that the liquid is evenly distributed throughout the subject. Water provides gliding of the abrasive surface and does not allow particles of dirt and rust to rise into the air.
Repair work will be delayed for a long time if you have to clean the iron gate or fence. In such situations, the spatula is replaced with a grinder or a drill. You will need a nozzle with hard villi. They put it on a power tool and grind a cast iron or iron product until the layer of protective suspension disappears.
The result is fixed with anti-corrosion impregnations that fill small cracks and chips remaining after mechanical cleaning. Items that are planned to be repainted are necessarily primed.
The method has several significant disadvantages:
- A drill or trowel leaves dents on objects with thin walls.
- Stubborn paint is difficult to remove mechanically.
- During operation, dust is raised into the air, consisting of an old coating, metal particles and rust. If a person does not use a respirator and goggles, substances enter the mucous membrane of the eye and nasopharynx, causing irritation.
If you need to clean large objects with thick walls, such as pipes, it is recommended to call a specialist with sandblasting equipment. The metal surface is treated with a jet of fine abrasive, which removes both paint and rust.
Removing the old coating from brass products
Doorknobs, iron plates, hooks and other accessories are cleaned carefully so as not to spoil. The old coating is first soaked and then removed mechanically.
You will need:
- ceramic pan;
- detergent;
- kitchen or office knife;
- nylon brush;
- kitchen tongs;
- screwdriver.
They use a knife to pry the plate, hold the blade between the fittings and the door. Unscrew the screws, remove the handle.Screw hats are cleaned with a knife or brush. You can use a paint thinner or methylene chloride.
Put metal fittings in a pan. Pour some water so that it covers the handle and plate. Add 2 tablespoons of detergent. Put accessories on the stove and turn on medium heat. Boil for 4-5 hours, then turn it off and leave the pan on the burner until morning.
The paint will soften during this time. Accessories are taken out of the water with kitchen tongs. The coating is removed with a nylon brush. Metal will not work, it is too stiff and leaves scratches on the handle. If the paint hardens and does not separate well, the hardware is immersed in hot water for 5-10 minutes.
After cleaning, the brass products are polished with a soft rag and beeswax to protect them from rust. Before painting, the pen and plate are degreased, a layer of primer and a new coating are applied.
Chemical options
Metal objects with a raised surface are treated with solvents. They are:
- universal;
- substances for ferrous and non-ferrous metal;
- multifunctional, removing paint along with putty and primer;
- means for removing oil-based coatings.
Tip: It’s better to buy a wash at a hardware store. Powders and emulsions for removing paint from metal are also sold in car dealerships, but there they cost two to three times more.
Solvents soften the old coating, but it will be necessary to separate it from the base with a brush with hard bristles or a spatula. The person who has chosen the chemical method should stock up on a respirator, goggles and rubber gloves. You will need a special suit and shoes.
The wash is applied in a thick layer using a brush. Paint is removed in several stages:
- The metal surface is wiped with a damp cloth, cleaning from dirt, then disinfected.
- The prepared object is treated with a solvent, covered with a plastic film so that the substance is better absorbed into the old coating.
- 5–20 minutes are detected. The time depends on the type of wash and the thickness of the paint coat.
- The soft coating is stripped off with a spatula and sweep into a heap, so as not to trample into the ground or floor.
- Remains of paint are removed with a stiff brush with a metal pile.
The surface must be wiped with special compounds, for example, mineral kerosene, to remove the solvent. The substance must not be left on a metal base, otherwise a new coat of paint will not be able to fix and disappear.
Acetone is able to soften the old coating. A cloth or gauze is impregnated with a liquid, applied to a metal surface. Seal with plastic wrap on top, fix the structure with tape. Leave for 10-12 hours, so that acetone is absorbed and begins to work. The fabric is removed gradually, immediately clean off the paint so that it does not have time to harden.
The cleaned surface is coated with an anti-corrosion primer. Some aggressive compounds destroy metal objects and provoke the appearance of rust.
Thermal method
To remove several layers of stubborn paint a blowtorch, building hair dryer or gas burner will help. The metal surface is washed, removing dust and dirt, and after drying it is treated with fire or a stream of hot air.
High temperatures soften the old coating. It is separated from the metal surface, bubbles appear. Heated paint is immediately removed with a spatula or knife. In your left hand you need to hold a blowtorch, and with your right hand peel off the coating. You can work together to finish faster.
There should not be any flammable objects made of wood, paper or fabric near the surface to be treated. The paint is removed carefully so that hot particles do not get on the skin. The softened coating is eaten into the epithelium and a burn remains, which does not heal for a long time.
Do not burn cast iron or brass products.Some types of metal are scaled, brittle, and destroyed after being treated with a blowtorch. On others, cracks from uneven heating appear. Do not use a gas burner or building hair dryer indoors. Paint emits toxic substances, so work is carried out outdoors or in a ventilated area.
It is possible to remove the layer of the old coating quickly and effectively mechanically or chemically. Washings and brushes do not destroy metal surfaces, do not leave dents or cracks. The thermal option is rarely used and all the minuses and advantages of such purification are necessarily weighed.
Video: how to remove old paint from a metal surface
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