What does galvanizing give metals?
Zinc plating is the coating of various metal surfaces with a layer of zinc to protect against corrosion. The fact that it is galvanizing is the most effective method of rust control was found out long ago, more than 200 years ago. When investigating different methods, it was galvanizing that showed the most long-term results – metals covered with a layer of zinc did not rust for over 50 years.
Since then, anti-corrosion specialists have been using various methods of galvanizing. Originally it was hot-dip galvanizing, then galvanic, diffusion and gas-dip galvanizing. But in the 80s of XX century there was a definite breakthrough in this field and a new method – cold galvanizing – appeared.
Cold galvanizing is the most convenient, economical and durable method of galvanizing. It consists of coating a prepared metal surface with a composition with a very high (96-98%) zinc content, as well as with different additives. Cold-dip galvanizing can be done with a usual brush or roller right on the spot, i.e. there is no need to take the construction to another place. The result of this protection is the absence of corrosion for 25-50 years, and metals protected by cold galvanizing corrode 3 times slower than protected by other methods, despite the same zinc in the composition (according to studies made by Fulmer Center). So what’s the secret?
How does zinc plating work?
Iron reacts with moisture and oxygen and oxidizes. It produces a crumbly, flaky film on the surface which gradually turns into rust. This unreliable protection continues to let moisture and oxygen deep into the iron and destroy it. But zinc, tin and aluminum, when interacting with moisture and oxygen, form a strong film that does not allow destruction to continue. That is why a thin layer of these metals is used to protect other metals that are more susceptible to corrosion.
Zinc stands out among this group of strong metals in that it provides further protection from moisture and oxygen even if the coating is damaged, while the protection of tin or aluminum weakens or even begins to contribute to corrosion if the integrity of the layer is compromised.
Zinc protects metals in two ways at once – barrier (passive) and cathodic (also called active, protector or electrochemical).
Cathodic protection implies that zinc, when applied to iron, forms a galvanic pair with it, in which iron is the less active metal and zinc is the more active one. On contact with moisture and oxygen, the zinc-anode reacts first, donates its electrons to fight corrosion, and the iron-cathode accepts the electrons, protects itself and remains virtually untouched by rust. The protective process continues until the zinc layer is completely depleted.One layer of 40-60 μm lasts for 10-25 years.
At once 2 methods of protection, which replace each other, are very useful for metals from the first day of operation. The fact is that any coating composition is not 100% airtight, and has defects and pores. Zinc coating can also allow some amount of oxygen to pass through during the initial phase of use. This is when it protects metals from rust by treading or electrochemical means. During use, the coating structure thickens, the zinc compounds dissolve completely and barrier protection comes into effect, as with hot-dip galvanizing. If the coating’s integrity is damaged (scratches, mechanical damage, corrosion by chemicals), the cathodic protection takes over again.
Not just zinc – or why cold galvanizing protects longer?
In practice, zinc coating is the most reliable and durable. However, one zinc coating is not the same as another. You can buy a paint with zinc, apply it properly, but the protection will not last for decades. Because the zinc added to the paint will not work that way. Only cold-dip galvanizing compositions give such long-lasting protection (25-50 years). So why is cold galvanizing more durable than other zinc treatments?
Cold galvanizing provides the same protective characteristics as other methods, such as hot-dip galvanizing. But, in contrast, it is much easier to apply at the construction site, costs less and lasts longer.
Cold galvanizing compositions contain 96% and more of zinc, with 99,995% purity. That is practically 100% impurity-free! The higher the zinc concentration and purity, the longer the coating will last. That’s what makes “cold” coating corrode as slowly as possible in comparison with other galvanizing methods. The zinc particles in the composition are protected by resins – this further increases the protective characteristics of the coating. Besides, the minimum size of particles (from 12-15 microns to 3-5 microns in different compositions) and their oval shape provide strong electrochemical bonding with the metal. Because of this, even scratches and damage to the coating surface do not cause it to peel off, maintaining excellent adhesion. Only active coatings with cathodic protection can do that. Coatings that just have zinc in them can’t do that.
Even a proven galvanizing method like hot-dip galvanizing is slightly inferior to cold-dip galvanizing. That’s because hot-dip galvanizing uses compositions with zinc content of 80-85% with purity up to 98%. The resins, protecting zinc, are absent there, as they can’t withstand heat up to 400°C and will lose their protective properties anyway. Besides, not every construction can be dismantled, transported and placed in a hot zinc bath.
How long will a cold applied zinc protection last?
The operating time of cold zinc plating varies depending on operating conditions and layer thickness, as well as the degree of cleaning of the metal surface. Contaminated air, the influence of different chemicals, gasoline, salts, alkalis and petroleum products can insignificantly, but accelerate the depletion of the coating. The life of a coating used outdoors is always shorter than that of a more gentle indoor use.
The time periods guaranteed by the manufacturer for Barrier-Zinc cold galvanizing compositions:
Dependence of Layer Thickness and Life of Barrier-Zinc Coating:
- 40 microns: 7-10 years;
- 60 μm: 10-20 years;
- 80 μm: 14-25 years;
- 100 μm: 18-25 years;
- 120 μm: more than 20 years.
It is worth noting that these are the terms guaranteed by the manufacturer. The real life of the coating is 1.5-2.5 times longer than the warranty. In addition, the service life of such a coating can always be extended, at any time, by adding another layer and making it thicker.
Our website offers other zinc-containing primers that provide reliable and durable protection of metal against corrosion. For example, Barrier-Grunt is a one-component anticorrosive primer with zinc to protect metal in different environments (soil, water, atmosphere).
Do you have any questions about the composition? Contact the representative office in your city:
in St. Petersburg: +7 (812) 603-41-53, +7 (921) 927-58-47 in other cities: 8 (800) 707-53-17 e-mail: email@example.com
Rating of effective rust converters with zinc: rules of use, prices, opinions of buyers
Means belonging to the category of converters with zinc, help to cope with a rusty deposit and permanently protect the metal surface from corrosion.
The active action of the reagent is due to the complex composition, in which the zinc component plays an important role.
In order to successfully select and apply the converter, it is necessary to objectively compare analogues and not to violate the technology when cleaning the product.
From this article you will learn what is a rust converter with zinc, how the product works, how to use it, what are the reviews of consumers.
What is it, how does it work?
Converters of rust with zinc – these are specially designed means, which contain in their formula not only substances that react with iron oxides, but also zinc salts.
The acids (e.g. orthophosphoric acid) can play the role of the former. The active components cause zinc to react chemically with oxygen and to become an insoluble inert compound.
The action of zinc is based on the chemical nature of metals. Zinc has a higher charge than iron. This explains its greater chemical activity: it reacts faster with electrolytes.
Externally the reaction product looks like a thin film that covers the surface of a product. That it protects the metal from moisture and the new appearance of rust.
Some converters as additional ingredients also contain manganese, which strengthens the protective film layer.
Galvanizers as well as monocomponent converters form a loose layer on the metal surface that has to be removed. But at the same time the zinc inhibitor forms an additional primer coating under it, which is not present after acid and neutral cleaners.
How do I use galvanizers?
Zinc inhibitors are used for cleaning and galvanizing
- metal grills,
- piece goods.
Treated areas can be painted or repaired. To keep the result of zinc plating for a long time it is necessary to follow the rules of application. Each converter is supplied with its own manual.
But there is a common scheme of application for all the zinc-converters:
- The thick oxide layer is brushed off mechanically.
- The treated area is degreased.
- Shake the bottle with the converter.
- Apply the product to the rusty surface.
- Sustain the prescribed time.
- Grind away the top loose layer to a protective film.
- Coat the metal with primer and filler.
- Paint the treated surface in a suitable tint.
Most converters are designed to work at positive temperatures (+10 to +30 degrees).
Experts recommend using converters with zinc when rust is weak or absent at all. Galvanizers have proven to be excellent preservatives and corrosion blockers. That’s why they are good for cleaning and ideal for preventive care.
Which one should I choose?
The modern market of chemicals designed to protect against rust is represented by a wide range. To determine the best product, it is advisable to consider several points.
First, the effectiveness of cleaning from the rust layer and the quality of the protective coating are important. Second, it is recommended to pay attention to the prolonged effect. The duration of protection can play a decisive role.
Another important criterion in the choice is the ease of use . Converters can be:
- paste consistency.
The choice should be made based on the quality, shape and area of the surface to be cleaned.
If you need to treat a hard-to-reach area, the aerosol is helpful. This product is convenient to apply if there is no possibility of direct contact with the surface.
When cleaning the horizontal surface of a large area, gels and liquids are advisable. If the rust has an insignificant spread or is localized on an inclined surface, it is better to use a paste or gel.
About the properties of converters manufacturers report in the description on the packaging. However, for the sake of objectivity, it is recommended to take into account the reviews of consumers who have already experienced the means in practice.
Converters differ not only in efficiency, ease of use, but also in price. The price-quality ratio must be optimal, so the money invested will be recouped by the result and the duration of the anti-corrosion protection.
Top 5 best agents and reviews of them
Below are the most popular rust converters with zinc:
The formula includes:
- orthophosphoric acid,
The film that forms after treatment of the product promotes stronger adhesion of the primer and paint to the surface.
The liquid is applied to the metal twice. After the second layer ASTROhim is applied keep for 20 minutes and then rinse with water. Otherwise there is a risk of damaging the metal.
The average price for a bottle (500 ml) is 120 rubles. Most users (85%) recommend ASTROhim for use. The low price is noted as an advantage. The effect is rated as “excellent”.
The only inconvenience is a pungent smell, which is felt after applying the remedy. Read the reviews here.
The chemical is presented in aerosol form . Characterized by deep penetration, long term protection, good adhesion. The converter is popular among car enthusiasts and professional car repair shops.
The spray is applied in two or three layers with a two minute interval. Remove excess product with alcohol. It is necessary to wear personal protective equipment before use.
A bottle of 255 ml is estimated at an average of 600 rubles. Reviews confirm the high effectiveness of Hi-Gear. The product does not damage the paint when it comes into contact with it. The formed film lasts for 3-4 months.
As disadvantages, the extremely high price is noted. Reviews can be found here.
The liquid converter with orthophosphoric acid forms a strong protective layer of light gray color. Care should be taken when treating painted surfaces, as the strong compound is capable of corroding paint and varnish. Suitable for metal and ceramic products.
The product is applied with a brush or sprayer. According to the instructions there should be two layers. The time interval between them is 15-20 minutes. Finishing coat can be applied after 2 hours after treatment.
A 500 ml bottle costs an average of 80 rubles. A liter bottle with an atomizer is priced at 200 rubles.
More than half of the users (73%) recommend “Chemist” for use. The reviews note a good result, economical consumption, an acceptable price. To the disadvantages include the toxicity of the composition.
LAVR Rust remover
A liquid product of the “10 minutes” series is suitable for the treatment of surfaces that have been subjected to severe corrosion. LAVR is characterized by rapid penetration into the rust layer.
The formula is made up of:
- mixture of organic and inorganic acids,
According to the instructions, spread the converter on the surface with a sponge, rag or brush. If the bottle has a sprayer, spray the product from a distance of 15-20 cm. After a quarter of an hour, the remnants of chemicals and rust are scrubbed with a brush. Rinse the metal with water and wipe dry.
A 500 ml bottle with a trigger costs an average of 200 rubles. There is almost no criticism in the reviews. The only comment is the possible irritation of the skin of the hands in the absence of gloves. The efficiency of LAVR, ease of use, adequate price and economy are unanimously recognized.
As a part of the liquid means include:
- orthophosphoric acid,
- active additives.
Application of the product is standard: the liquid is applied once to the rust until the rust is completely wet. After drying remove the remains of galvanizing and loose layer.
AUTOPROFI bottle (500 ml) with a spray nozzle sold for 230 rubles. Reviews emphasize that the converter copes with the task of removing oxides. The zinc remains in the form of whitish streaks.
But the category of “galvanizing” AUTOPROFI does not hold its own. The disadvantage is the low information value of the label: it does not specify the durability time.
Where and for how much to buy?
Zinc converters are not scarce. They are not difficult to find at car and hardware markets, in large construction stores. An even easier way to buy the product is to order it from an online store.
The cost per pack is determined by the brand, the volume of the bottle, the pricing policy of the retail outlet. In this case, not always the budget is associated with poor quality. The figures on the price tags range from 80 rubles to 600.
Tips for use
Anticorrosives with zinc are convenient and effective in use. But to exclude possible problems and to achieve the ideal result, it is desirable to remember and apply in practice the following tips:
- Before applying galvanizing to an expensive product, it is advisable to test it.
- Most converters require the use of gloves.
- The treatment should be carried out outdoors or in a ventilated room.
- It is necessary to treat the whole surface to stop the corrosion.
- Remains of the converter and the loose layer are removed with a brush without metal lint.
- If necessary, treatment of metal with the converter is repeated.
- For preventive purposes after some time the product should be coated again with galvanized.
All the most important and useful information about rust converters can be found in this section.
Modern converters with zinc are an effective solution to protect metal surfaces from oxidation. The rich range of galvanizers allows you to choose the most suitable option in a particular situation.
At the same time to get a satisfactory result it is important to follow the technology of treatment and additional recommendations for the protection of metal.