Even metal has a limited lifespan - let’s make sure it’s properly protected

Materials such as iron, steel, zinc, copper, aluminum and other metals are used everywhere. In almost every home we can find fences, stairs, windows, doors, radiators or other pieces of furniture with metal elements. It is often the case that poorly protected or completely unprotected surfaces have changed their original appearance or are deteriorating as a result of atmospheric effects.   With proper protection, the deterioration can be prevented or at least limited, thus prolonging a product’s lifespan.Long-term protection is achieved only with a correctly prepared surface and a properly selected coating system. Below, we have prepared some basic tips for how to prepare and paint metal surfaces.

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Pick a sunny day for painting, with no rain or fog, as high air humidity can have a negative impact on the drying of the coating. We recommend not painting objects in the morning when they are still covered in dew, but rather waiting for them to dry and warm up to the ambient temperature.

Grease and similar impurities should be removed with a suitable cleaning agent or thinner prior to painting. Old paintwork that no longer adheres to the surface should be completely mechanically removed, using paint removers or heat. An undamaged coating that only needs refreshing should just be cleaned and lightly sanded.  

Remove rust mechanically, by sanding or grinding. On galvanized sheet metal, copper, brass or aluminum, the use of a wire brush or metal wool is not recommended. If rust is removed with acid-based chemical agents (phosphor), the surface must be thoroughly rinsed with water and dried and only then can it be painted (if using a solvent-based paint), as any substance remnants hinder drying.

The biggest enemies of metal objects are water and air. This is why metal objects are first always protected with a basic anti-corrosion coating, which prevents rusting and improves the adhesion between the surface and the cover coating.   For long-term protection, we recommend applying at least one coat of a primer, and on more exposed surfaces, two layers of coating, which will protect the metal surface from rust and improve the adhesion of the finishing coats. 

Only after a surface has been protected against rust can top coatings or enamels be applied, which give the surface the desired decorative effect. Enamels also protect the surface, as certain colour shades and gloss levels protect the metal against the effects of the sun and rain. For external use, we recommend the use of gloss coatings, which are more resistant to atmospheric effects and need to be restored less often. 

The choice of coatings depends on the surface and the desired final appearance.   In particular, attention should be paid when painting 'special' metal surfaces such as galvanized sheets, copper, aluminum or brass, which are known as ‘difficult' surfaces to paint, as common commercial paints often have poor adhesion.   For the long-term protection of these surfaces, we recommended using a coating specially adapted to the selected surface. 

To maintain good protection and a good appearance, we recommend regularly inspecting all metal surfaces.   Under normal conditions, it is sufficient to do this once a year. Special attention should be paid to horizontal and sun-exposed surfaces, which are more susceptible to weather conditions.

 

Tips for the task and selecting a suitable paint:

  • choose the right paint for your product with the help of the instructions on our website or on the packaging, taking into account the conditions to which the product is exposed;
  • if you need to apply several layers, use the same manufacturer's paint for all layers; 
  • different paint qualities must not be mixed, even if they are from the same manufacturer;
  • only thin the paint if this is necessary for the chosen application method (e.g. for spraying), using the thinner prescribed in the instructions;
  • perform a test on a small part of the old paintwork prior to painting, to check that the new paint doesn’t dissolve or soften the old one;
  • it is necessary to test the paint adhesion on a clean surface prior to painting an aluminum surface;
  • when painting large surfaces, paint the entire surface at once – do not stop and start;
  • if possible, objects that will be painted should be positioned horizontally;
  • objects that are attached should be painted back to front, and bottom to top (e.g. fences);
  • apply the paint in several thin layers and according to the time intervals stated in the instructions;
  • to achieve a more beautiful appearance, slightly sand the surface before applying the following coat;
  • mix the product thoroughly prior to each coat;
  • wash the tool immediately after use, with thinner (when using solvent-based paint) or with water (when using water-based paint) and dry it;
  • any stains that form while painting should be removed with NITRO or TESSAROL thinner while still fresh;
  • pour any leftover paint into a suitable smaller container and close it well;
  • be careful with the storage temperature, especially with water-based paint (acrylic paint) - the paint must not freeze.

 

Frequent mistakes when protecting metal and why they occur:

  • poor adherence of the coating – the surface was poorly cleaned, there is grease, rust and residues of paint strippers, there is water vapour condensation on the surface
  • rust - the coating was used without prior use of a primer, the surface was poorly cleaned
  • inferior paint spreading rate, brush traces - excessive paint or unsuitable thinner was used, lower layers piled up, the temperature was too high
  • rough surface - the layers were not sanded
  • soft and non-resistant paint layer – individual layers were applied too quickly one after the other or the paint was applied too thickly
  • inferior coverage and inadequate protection - the paint was applied too thinly, the paint was excessively thinned 
  • longer drying time, matte appearance and orange peel texture - the paint was applied at too high or too low temperature and air humidity, an unsuitable thinner was used
  • the paint curdles - the recommended thinners were not used
  • the paint does not dry - chemical paint removers were poorly removed, the humidity is too high and the temperature too low, the paint was applied too thickly in one layer
  • porous surface - the paint was applied too thinly, the paint was excessively thinned
  • paint cracking, hairline cracks and wrinkling - unthinned paint was applied in a single thick layer
  • peeling – the surface was poorly cleaned and old coatings that no longer adhere to the surface were poorly removed, the tools were poorly cleaned, a suitable primer was not used
  • visible dents under the paint - damage on the surface was unremedied
  • appearance of lumps on the surface – the tools and surface were poorly cleaned, a suitable primer was not used
  • a cracked coating film after drying - water-based coatings were applied at too low a temperature

 

Rust

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Inferior coverage and inadequate 

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Peeling 

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Appearance of lumps

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Visible dents, unremedied damage

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