Rules for using acid to remove rust from metal, how to dilute
Acid has been successfully used for a long time to remove materials destroyed by rust from metal parts. The reagent allows you to permanently remove the crumbly, red-brown layer from the surface. In addition to the chemical method, there are others that are used in industry, small-scale production and everyday life. Let's analyze together how effective they are, why it is necessary to remove rust from metal, how dangerous it is.
Causes of corrosion
A prerequisite for the formation of brown spots, the destruction of the metal can be not only contact with moisture. Sometimes the future home hides under a coat of paint, waiting for a chance to prove itself. The storage of metals and metal products in a humid and poorly ventilated environment also leads to the appearance of foci of corrosion.
And in addition neglecting cleaning, protection will lead to the development of small areas into large areas, to the defeat of large areas. For thin metal (bodywork), such inaction will end in disastrous and expensive repairs.
Cleaning methods
There are several working methods to get rid of metal corrosion. Experienced metalworkers successfully use them alone or in combination, depending on the complexity of the situation. These include the following methods:
- mechanical cleaning;
- chemistry;
- alternative (improvised means).
Which one to choose, to solve the problem for the owner himself, taking into account the available resources, including reagents, time, the scale of the defeat.
Mechanical
One of the most practiced rust control methods. It consists of the slow but sure removal of corrosion products from the surface of steel or alloys. Used stiff brushes, special accessories for power tools, abrasives. At the end of the procedure, dust and dirt are removed, the released metal is cleaned and dried.
chemical attack
Consists in the treatment of rusty parts, surfaces with concentrated acids. Alkalis are less commonly used.
An elementary chemical reaction occurs: under the action of a reagent, the iron oxides form a salt.
The process is not fast, moreover, it is slowed down by the use of a weakly concentrated composition. But as a result of processing, loose, exfoliated fragments dissolve into pure metal. It remains to remove, wash off the residues of the reaction with water.
The use of folk remedies
It is already clear what to do, having experience, knowledge and the ability to use industrial methods to solve the problem. But what if all that wasn't there? We will have to use alternative and folk methods.
How to remove with acid
Acid is the main component of many commercially available rust converters.Only there are some additives in the composition, but at home it is quite permissible to do with a clean solution. You will need:
- One of the acids (phosphoric, oxalic, citric).
- Water to dilute the solution to the required concentration.
The ready-to-use composition will withstand point and focal metal corrosion without any problems.
sorrel
The acid contained in the plant of the same name is sold in stores in a dry state, in the form of white crystals. To obtain a working solution, the powder must be diluted in water, avoiding contact with the skin, mucous membranes and organs of vision. It is strongly recommended to use protective equipment when working with acids: goggles, coveralls, gloves.
To prepare a working solution, you will need 5 teaspoons of powder, as well as 250 milliliters of pure water. The crystals are stirred until completely dissolved, then the part is submerged (or covered with a soft brush). After about half an hour, depending on the oxidation state of the metal, the product is washed off and then wiped dry.
Orthophosphoric
Phosphoric acid is one of the rust converters and is used to remove corrosion products from ferrous metals. It should be used with care to avoid burns. The composition is applied drop by drop, with a brush, on large surfaces - with a paint roller or a spray bottle. Subject to appropriate protective measures, acid does an excellent job of cleaning parts and metal surfaces from oxides.
Lemon
"Lemon" food also refers to acids. The bag with the reagent is poured with warm water or immediately on the workpiece, then diluted to a pasty state - whoever prefers what is better.The effect of using citric acid will be no less strong than that of other solutions. At the end of the procedure, the metal is cleaned of corrosion residues, washed and wiped dry.
Special acid-based cleaners
Someone will say: why invent something if there are ready-made solutions? Yes, there's a reason for that, because there are rust cleaners on the shelves at any hardware store. This is a Bison brush attachment, rust remover, corrosion converter.
It is enough to purchase the selected composition, follow the instructions and, as a result, get pure, oxide-free metal.
Bison
The brush is a special accessory for a drill. Hard wires, which are placed on a metal disk, rotating at high speed, work like a hand brush, but much faster. When working, you must protect yourself from fine dust with the help of coveralls, goggles and a respirator. To remove a thin layer of rust, nothing better than a Bison. The brush can be used repeatedly as needed.
Rustproof
A chemical reagent, a clear, slightly oily acid-based liquid. Delivered ready to use, packaged in plastic bottles. The composition is applied to metal surfaces with a thin layer so that it covers the entire affected area. Corrosion products dissolve, turning into an inert film on a chemically pure metal. No additional processing is required, you can immediately start painting.
rust converter
Another composition based on phosphoric acid. Effective against oxides and corrosion products. Does not require removal from metal surface after treatment is complete.
Industrial prevention methods
In addition to forced rust cleaning, there are methods to prevent metal oxidation. These include:
- galvanic treatment;
- cathodic protection;
- application of inert coatings.
In domestic conditions, these methods are problematic to apply due to the lack of suitable equipment, the complexity of technological processes.
Galvanization
The process consists of spraying a thin layer of a substance that is weakly prone to oxidation on a ferrous metal by electrolysis. The nuance of the situation is that as soon as the protection is violated, corrosion begins immediately.
Cathodic protection
A method involving the use of a direct current source, which creates an area of negative electrical potential on the protected surface. It is successfully used on large objects (ships).
The weak point is the need for a continuously operating battery that powers the device.
Special coatings
Methods of protection using specially applied metal coatings cannot be less effective than others. Usually, for their manufacture, substances are used that do not react with condensate or moisture.
Galvanized
The coating with a layer of zinc perfectly protects the base metal from oxidation, making it inert towards less aggressive media. It is widely used to protect body parts, in the manufacture of hardware, fasteners.
Tinning
The method is based on coating the metal with molten tin solder. The layer formed resists oxidation well and prevents the spread of corrosion.
chrome plating
It consists of applying a layer of chrome to the units and parts, which is practically not subject to oxidation.It saves you money by replacing expensive stainless steel production with ferrous metal production, followed by chrome plating.