The treatment and protection of rusty metal has always been an important topic in the industrial and construction fields. Once the metal surface is rusted, it will not only affect the appearance, but also lead to a decrease in structural strength, and even seriously affect the function and service life of the equipment. Therefore, timely and effective removal of rust on the metal surface and coating it with suitable bottom paint is a vital step in the protection of metal surfaces.
Among the many anti-corrosion coatings, bottom paint, as the first layer of anti-rust coating, plays a vital role in rust prevention, improving coating adhesion, and improving the surface state of the metal. For rusty metal, choosing a suitable bottom paint is particularly important, because it not only needs to solve the problem of rust removal and rust prevention, but also must ensure that the paint can be firmly adhered and provide a smooth and durable foundation for the subsequent topcoat.
So, what is the best bottom paint for rusty metal? This issue involves many aspects such as the type, composition, and use conditions of bottom paint. This article will conduct an in-depth analysis of this issue to help consumers, construction workers, and related practitioners make scientific and reasonable choices.
Why does metal rust?
Metal rust is caused by chemical reactions, usually the process of metal reacting with moisture and oxygen to produce metal oxides. Especially in an environment containing oxygen and moisture, the metal surface will react with moisture, oxygen in the air or pollutants to form rust. This process not only affects the appearance of the metal, but also weakens its physical properties. In severe cases, it may even cause damage to the metal structure.
Common rusty metals include iron, steel, aluminum, etc., especially iron and steel. Once rust spots appear on the surface, it not only affects the appearance, but may also cause structural performance to decrease. Therefore, it is particularly important to treat and protect rusty metals.
What is the role of bottom paint in rusty metal painting?
Bottom paint is the bottom layer of the painting. It mainly plays the following roles:
1. Anti-rust protection
For rusty metals, the primary task of bottom paint is to prevent further oxidation reactions. Anti-rust bottom paint forms a protective film to isolate oxygen and moisture in the air, thereby reducing the development of rust.
2. Enhance coating adhesion
Metal surfaces, especially those that have been rusted, may have irregular roughness, which reduces the adhesion of the paint. Bottom paint can fill these tiny gaps and unevenness, enhance the bonding between the topcoat and the metal surface, and ensure the durability of the coating.
3. Improve the surface condition
Bottom paint can also smooth the metal surface, making the paint more uniform during the subsequent coating process, which helps to improve the final coating effect. It can effectively fill rust spots or tiny holes on the metal surface to form a smoother coating foundation.
4. Improve corrosion resistance
Some high-quality bottom paints also have special functions such as acid resistance, alkali resistance, and salt spray resistance, which enhance the corrosion resistance of the metal surface and extend the anti-corrosion protection period.
What are the common types of bottom paint for rusty metal?
Different bottom paints have their own characteristics in composition, performance and applicable environment. For rusty metal, there are usually several main types of bottom paint to choose from:
1. Zinc-rich bottom paint
Zinc-rich bottom paint is the most common type of anti-corrosion coating. It forms a layer of metallic zinc coating through zinc powder or zinc alloy particles, thereby acting as a sacrificial anode. Zinc itself has good corrosion resistance, and in electrochemical reactions, zinc will corrode first, thus protecting the underlying metal from further corrosion.
Advantages of zinc-rich bottom paint:
● It has excellent corrosion resistance and is suitable for metal surfaces such as iron and steel.
● Zinc powder plays an electrochemical protective role in the coating and can effectively prevent rust.
● Suitable for harsh environments such as marine climates and industrial areas.
Disadvantages of zinc-rich bottom paint:
● In some special environments, the adhesion and durability of zinc-rich bottom paint may be limited.
● The construction requirements of zinc-rich bottom paint are high and need to be operated according to specific processes.
2. Epoxy bottom paint
Epoxy bottom paint is a bottom paint commonly used on metal surfaces, especially rusty metals, with strong adhesion, corrosion resistance and wear resistance. Epoxy resin can form a tight protective film during the curing process to prevent moisture, oxygen and chemicals from corroding the metal.
Advantages of epoxy bottom paint:
● High adhesion, able to adhere firmly to the surface of rusted metals.
● Strong waterproof and anti-oxidation ability, suitable for humid and cold environments.
● Good chemical resistance, can prevent some acidic or alkaline substances from corroding metals.
Disadvantages of epoxy bottom paint:
● Epoxy bottom paint needs to strictly control the ambient temperature and humidity during construction, otherwise the coating may crack or fall off.
● The price is relatively high, especially for some high-end epoxy bottom paint.
3. Polyurethane bottom paint
Polyurethane bottom paint is widely used in corrosion protection of various metal surfaces due to its good adhesion and weather resistance. It can form a hard coating on the metal surface, which can not only prevent rust, but also provide additional UV resistance and wear resistance.
Advantages of polyurethane bottom paint:
● Good weather resistance and wear resistance, suitable for high temperature and high humidity environments.
● High adhesion, especially suitable for metal surfaces, can provide long-term protection.
● Strong chemical corrosion resistance, can maintain stable performance in various harsh environments.
Disadvantages of polyurethane bottom paint:
● Polyurethane bottom paint is expensive and has a higher cost than other paints.
● It has high construction requirements and requires professional personnel to operate.
4. Acrylic bottom paint
Acrylic bottom paint is a water-based paint with low toxicity and volatility. It is suitable for indoor and some environments that do not require extreme anti-corrosion performance. It is suitable for lightly rusted metal surfaces and can provide effective anti-rust protection.
Advantages of acrylic bottom paint:
● Low volatility, good environmental performance, suitable for use in low temperature environments.
● Easy construction, suitable for home or small-scale construction.
● Relatively low cost.
Disadvantages of acrylic bottom paint:
● For severely rusted metals, the anti-corrosion effect may not be as good as epoxy or zinc-rich bottom paint.
● Relatively poor durability, suitable for mild environments.
5. Phosphate bottom paint
Phosphate bottom paint is a coating formed by chemical reaction, which can effectively improve the adhesion and anti-rust performance of metal surfaces. Phosphate coating is usually used on irregular or pickled metal surfaces, which can provide additional anti-corrosion protection.
Advantages of phosphate bottom paint:
● Provide additional metal surface protection and effectively prevent rust.
● Strengthen the adhesion of the coating, especially suitable for irregular or untreated metal surfaces.
● Easy to apply and can dry quickly.
Disadvantages of phosphate bottom paint:
● Limited anti-corrosion effect, suitable for some slightly corroded metal surfaces.
● Compared with other anti-corrosion materials, it has poor durability and requires regular maintenance.
Founded in 1994, Huaren Chemical Industry Co., Ltd. is a Chinese company known for manufacturing and exporting high-quality industrial coatings and resins. With 30 automated production lines and an output capacity of more than 20,000 tons annually, we are your one-stop factory for paints like epoxy bottom paint, acrylic bottom paint, chlorinated rubber, and more. We serve diverse markets, from shipbuilding and construction to mechanical and petrochemical industries. Our pricing is highly competitive, with flexible wholesale options and personalized customer support.
