Discuss the methods of removing old coatings from steel surfaces

Thread Content

Let’s discuss the methods for removing old coatings from steel surfaces. The removal of old coatings depends on the degree of damage to the coating layer as well as the specific requirements for that coating; it can be removed entirely or partially. Manual, mechanical, sandblasting, and flame rust removal methods can all be used to remove old coatings. Furthermore, strippers are widely used to remove old coatings. Paint removers are divided into acidic paint removers, alkaline paint removers, and neutral paint removers. Paint removers, also known as paint strippers, paint washers, or paint eliminators, are composed of a mixture of solvents such as chlorinated hydrocarbons, esters, alcohols, and benzene derivatives. By utilizing the solvent’s ability to penetrate and swell the covering layer, it is possible to effectively remove paint, coatings, and other substances from the surface of various substrates. For coatings with different film-forming substances, different paint removers can be used; for example, old oil-based coatings are usually removed using alkaline paint removers, while old coatings made of synthetic resin paints are typically removed with organic solvent-based paint removers. However, due to the corrosive effect of alkali solutions, and if not controlled properly, they can easily damage the steel surface; therefore, organic solvent strippers are commonly used for removal, with the choice of stripper determined by the type of existing coating. When using a paint remover to remove the old coating, first remove dust, moisture, and oil from the surface of the part to be treated. Then apply the paint remover to the old coating using a bristled brush, applying a thick layer of it. Wait for about ten minutes (this time should be extended in winter); once the old coating swells or softens, it can be gently removed with a spade. If the old coating is thick, it can be applied several times to remove it. When using organic solvents to remove paint, since the paraffin contained in them often remains on the surface after the old paint has been removed, affecting things such as the adhesion of the new coating, it is necessary to clean the surface with gasoline or similar substances. The role of paraffin in the paint remover is to slow down the evaporation of organic solvents, allowing it to act on the old coating for a longer period of time. When the temperature is too low, paraffin will precipitate, affecting the paint removal effect. Therefore, the paint remover should be placed in a place with a higher temperature, and used after it has melted evenly. Be sure not to heat it with an open flame! The entire operation should be carried out in a location free from open flames and with good ventilation, to prevent fires and poisoning.