The operation of metal structures and parts is often accompanied by exposure to aggressive environments. Examples include car bodies, and roof decking with fences and all kinds of frame sheathing. It is not always necessary to correct emerging defects by welding or a leveling tool, but embedding with a primer mixture may well justify itself. And best of all, metal putty with a wide range of protective effects will cope with this operation.
Cover assignment
Putty has a protective and restorative effect on metal surfaces. In practice, it is used as an intermediate layer between the structure of the workpiece itself and the outer decorative coating. In some ways, this is a preparatory base for ordinary paint, but designed forincreased protection of the base material. For example, heat-resistant putty for metal is able to reflect thermal effects at a temperature regime of -50 … + 120 ° C, while maintaining primary mechanical properties. Depending on the modification, this agent can provide protection against corrosion, aggressive alkalis, gasoline, weathering and direct contact with water. Therefore, there are special compositions focused on operation in industrial conditions, outdoors, indoors, in electric power plants, etc.
Material Composition
A large proportion of almost any putty of this type is epoxy. The remaining parts are various kinds of pigments and modifying additives with plasticizers. For this reason, the coefficient of non-volatile elements is about 90%. The specific set of minor components of metal putty depends on the conditions of use. These can be both neutral substances for filling defects, and reinforcing fibers like fiberglass inclusions that improve the physical properties of strength. Sometimes additional elements are introduced already in the process of preparing the solution. These include chalk or kaolin, which contribute to the rapid hardening and drying of the mixture.
Varieties of coverage
The type of filler used is of fundamental importance for the technical and operational qualities of the putty. According to this parameter, the following types of the main component are distinguished:
- Finefiller. Provides a delicate smoothing effect, masking microscopic pores and forming a smooth surface. This is the best metal putty for cars, which can also be used as a topcoat.
- Lightweight base. Also a kind of fine-grained putty, but without a decorative effect. Suitable for working with small scratches, chips and cracks. A distinctive feature of this composition can be called a modest mass, which has almost no effect on the structural characteristics of the blanks.
- Coarse filler. In this case, the emphasis is not on leveling or preparing the surface for final finishing, but on the rough correction of serious defects on the surface. In essence, this is a primer composition, after which grinding is performed. Coarse-grained fillers are characterized by high strength and generally mechanical resistance.
- Reinforcing base. Even more wear-resistant composition, due to which large damage with through holes is eliminated. Just such compositions contain fiberglass and metal powder.
Preparing the surface for applying putty
Working conditions and target surface requirements may vary depending on the characteristics of the specific formulation. For example, before there was a separation between the primer and the putty itself, which was applied after the defects had been repaired. Today, the question of in what sequence and how the putty is laid, on the ground or on the metal, is not worth it. There isonly one rule - a directly damaged surface in order to strengthen and protect it can be processed directly by any composition that contains epoxy. Special and separate primer with other mixtures is not required. Another thing is that the surface should be cleaned as far as possible from traces of corrosion, scale, burnouts and dirt with oil stains.
Preparation of composition
The putty base is supplied as a dry mix in volumes from 0.25 to 60 kg. Initially, you should expect a consumption of approximately 600-700 g/m2 with a standard thickness of up to 1 mm. If you plan to use a pneumatic gun for spraying, then the consumption will be even lower - approximately 200-300 g/m2, taking into account that the coating thickness is halved. In this ratio, metal putty is prepared for painting for cars. The dry mix consists of two components, one of which is the base, and the second is the hardener. First, the base is mixed with water using a construction drill-mixer at low speeds. Next, a hardener is added and stirring is performed in the same mode for 10 minutes until a homogeneous mass is formed.
Cover laying
After keeping the finished mixture for 20-30 minutes, they begin work. Styling can be done with a pneumatic sprayer, and with a traditional spatula tool, and with a complete tube with a small nozzle, if we are talking about a small areaprocessing. Putty is applied to bare metal in equal layers over the entire area and immediately leveled. To distribute the mass throughout the site, it is worth using the plaster rule. Also, do not forget that the mixture, due to the peculiarities of the recipe, does not retain plasticity for long, so the operation should be performed as quickly as possible. According to the instructions, the viability of the mixed putty when applied with a spatula is 1-1.5 hours, and when working with a spray gun - up to 6 hours. After polymerization, the laid and distributed coating is polished with fine abrasives. To do this, it is advisable to use a grinder with a felt wheel. Then you can proceed to decorative paint and varnish activities.
What to consider when using the material?
Experts advise in advance to focus on favorable environmental conditions. It is best to perform work at a humidity of no more than 80% and a temperature not lower than +5 ° C. If the material after preparation turned out to be too viscous and causes problems during application (especially for sprayers), then it is worth using special solvents for metal putty - means of grades R-4 and R-5A. Do not forget about the chemically active substances in the composition of the putty. It will not be superfluous to use personal protective equipment throughout the entire workflow.
Conclusion
The functions of protecting metal surfaces from various kinds of threats have long been adopted by paint coatings. They also protect the material from light mechanicalinfluences, and from corrosive processes. But under the conditions of operation of the material in aggressive environments and taking into account the existing damage, the best solution would be the use of putty for metal, which has a repair and restoration effect. Its main advantage is that it does not allow existing foci of damage to continue destroying the structure from the inside. In addition, the protective properties of many epoxy-based primers outperform alternative coatings.
