How to properly plaster a metal surface – 3 ways

Plastering a metal surface is more difficult than plastering a traditional surface made of brick or concrete. Plaster finds it difficult to adhere to metal due to its smooth and non-porous surface, necessitating special techniques and preparations.

There are three tried-and-true techniques for applying plaster to metal surfaces that will guarantee a smooth, long-lasting finish. These methods accommodate various project requirements and materials, regardless of whether you’re working with steel, aluminum, or another metal.

This post will walk you through each method step-by-step, assisting you in selecting the best technique for your metal surface and taking into account crucial advice for durable results.

To guarantee that the coating adheres correctly and endures over time, plastering a metal surface calls for specific techniques. The post will walk readers through three efficient processes for priming and plastering metal surfaces, including the proper primers, application methods, and preparation stages for each method. Readers can prevent common problems like peeling and cracking on metal surfaces and achieve a smooth, long-lasting finish by knowing these techniques.

Plastering metal

Plastering is used to improve the appearance and provide protection for any metal components found in building structures, such as columns, beams, load-bearing stairs, and occasionally even entirely metal swimming pools.

Smooth metal bases, on the other hand, are more difficult to plaster. Unlike the plaster "shell," the material expands and contracts easily with temperature changes, so coordination between the movements of the plaster clothing and the metal base is required.

To guarantee that the plaster layer adheres to the metal, a metal mesh is utilized. Where metal components are attached to brick, concrete, or other types of walls, reinforcement is also required.

Because metal surfaces have unique properties, plastering them requires unique technology, beginning with the preparatory phase. Typically, the structure lacks "hooks" that the plaster could securely "grasp."

Even freshly out of the factory, rolled products are smeared with lubricant and other adhesion-inhibiting substance stains. Soot, rust, and other materials can be used to coat outdated products. Hardware also needs to be shielded from water infiltration.

The aforementioned things ought to be stopped, neutralized, or avoided. As a result, meticulous structure preparation is essential. By reinforcing, the plaster layer and the metal base must work together harmoniously. Reinforcement is also necessary for the joints between steel and other materials in structures.

Gypsum is by far the least appropriate type of plaster. Gypsum coating is only capable of withstanding modest, sporadic mechanical loads. It has the ability to take in water. Consequently, forming a damp layer on the base’s surface that prevents further transfer. Consequently, the plaster is easily damaged. Cement and lime-cement mixtures are regarded as appropriate for leveling.

Preparing metal for plastering

The surface is cleaned initially. Cleaning metal serves two purposes: first, it ensures adhesion, and second, it gets rid of things that can get stains on the plaster coating.

There are two approaches to cleaning:

• mechanical;
• chemical.

The metal surface is primed to improve adhesion and prevent corrosion after cleaning. Steel is susceptible to rusting not just from water. The condition of ferrous metal is chemically threatened by the active ingredients in the plaster solution.

Concrete contact is not used in order to increase metal adhesion. Plasterers are doing the right thing when they use products like GF that have anti-corrosion additives for priming.

Mechanical cleaning of the surface

Steel brushes are used for manual mechanical cleaning at home. If the surface is large, you can also use a grinder with brush or abrasive discs.

Surfaces are cleaned mechanically, with abrasive equipment, or by sandblasting in production and on building sites. After treatment, take out any leftover dust.

Degreasing the metal surface

The cleaning complex includes degreasing:

1. Steel that has not yet been used is degreased using white spirit, gasoline or special removers. To prevent corrosion in the future, the surface is protected with primers.
2. Oil traces are also removed with alkaline solutions that contain up to 10% surfactants. Suitable caustic soda (10% solution), 0.5% OP-7, a common powder used in everyday life (10 g per 1 liter of solution).
3. Soot is removed by washing the metal with a solution of hydrochloric acid (3%), after which the acid is removed with clean water.
4. If the rust layer is no thicker than 100 microns, the oxidized metal is removed with a rust modifier.

Which mesh to choose for metal plaster

Metal surfaces are unique in that they have very little roughness. Plaster on metal therefore needs to be reinforced. Not only does the plaster layer have a mesh attached to its base, but it also "ties" the coating to the building. Reinforcement improves the plastering robe’s strength and thickness and its capacity to tolerate high internal stresses without breaking down or failing in the face of external loads.

The least amount of mesh currently in use is appropriate for rabbits. The rabbits’ wires are flexible, making it challenging to pull on; a thick layer of coating will be needed. Additionally, the plastering mesh has faceted wires, whereas the rabid’s wire is round.

Typically, they employ more than just a plaster metal mesh. A 50 mm-cell masonry mesh can be helpful in certain situations. For instance, two different kinds of mesh will provide dependable reinforcement if plastering the pool’s metal walls with tile cladding is necessary.

1. The metal bowl is degraded.
2. The pantry is welded to the surface.
3. The surface is primed with undiluted Vetonit Dispersion, to which quarry sand is added (clean!).
4. Apply a spray.
5. Perform reinforcement with a plaster mesh (cell size 10 mm x 10), fixing it to the masonry.
6. Already on top of the plaster mesh, apply a layer of soil (add 10% Despirsion to the solution).
7. The first week, take care of the plaster layer, maintaining the surface moisture and the correct natural hardening mode of the solution.
8. Fill the pool with water, keeping it under load for a couple of days. After draining the water and drying, perform the cladding.

Additionally, you can use clamps to strengthen the beams and fix the rods in a variety of ways, including by drilling holes. Spot welding is more frequently utilized for fastening, though.

The tack points are spaced 25–20 cm apart. If the metal element is flush with the wall, the mesh is placed over the hardware and moved 15 cm to the nearby wall sections. There, it is fastened to the wall using tight or self-tapping nails.

You can also use fiberglass mesh fabrics that are held in place by finishing adjacent areas if the plaster layer is thin on metal surfaces and the hardware is small.

Method 1 Plastering over mesh

The process is comparable to plastering walls composed of other materials in that layers of mortar with varying compositions are applied to create the coating:

1. Splashing. The mixture is made of a liquid consistency with the addition (to increase the strength of the reinforced layer and better adhesion to the mesh) of fibrous components – waste, asbestos fibers, felt. Additives are introduced only into the spraying solution.
2. Primer – the main coat of a mixture of normal viscosity.
3. Covering (a layer of a mixture without sand or with fine-grained sand) is an optional step if decorative plastering is planned.

Method 2 Plastering over putty and mesh

Automotive putty can be used as a "rasp" for plastering on metal. Although this approach is more costly, it produces quality outcomes.

1. After cleaning the metal, apply to the surface layer of putty. Use a spatula to form an uneven grooved surface.
2. A layer of tile adhesive is applied to the surface formed in this way after it dries.
3. Often the surface is additionally strengthened by attaching a mesh in the same way as in the first method.
4. You can plaster metal over the adhesive layer (even with gypsum compounds).

Method 3 Dry plastering using gypsum board

Dry plaster sheets (kgl) can be used to cover a metal beam or staircase structure. This is accomplished by first processing the metal, then using standard profiles or wooden block inserts to create a frame that is fastened to the walls or ceiling. Drill-cut drywall sheets are screwed onto the installed frame.

Plastering again usually doesn’t result in any issues. For inexperienced artisans, this is the safest method. The likelihood of committing an error approaches zero.

Although plastering a metal surface can be challenging, it is doable with the correct technique. Depending on the type of metal and the conditions it will be exposed to, each method of applying plaster—cement-based, epoxy, or specialized metal primer—has advantages.

A well-prepared surface is essential. The key is to remove any rust, apply a bonding layer, and make sure the metal is prepared to receive the plaster. Ignoring these steps frequently results in inadequate adhesion and rapid degradation.

Making the proper material and technique choices will guarantee that your plastered metal surface is long-lasting and aesthetically pleasing.

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