Powder coating defects: a brief overview

It would seem that a high-quality anti-corrosion coating cannot be spoiled by anything. It looks spectacular and, thanks to the principle of application, simply fits perfectly on products of any shape. However, we often observe the presence of defects that are quite visible and spoil the appearance.

After all, everyone had such situations when you chose some thing in the store, brought it to the checkout, and after looking closely noticed a minor scratch, stain or, for example, unevenness? Of course, we ask you to change our product for another, because no one wants to pay for what is spoiled. Who in this case should be responsible for the fact that the product is no longer suitable? Store staff? No, because they just sell what they receive. They can choose a supplier and believe in quality, but at the same time, it is almost impossible to check the product 100%.

No one will be able to view thousands of batches, whether the paint is perfectly applied to every millimeter. This should be monitored by manufacturers. And if their products have noticeable defects, it means that they do not adhere to all the rules by which painting should take place. Such negligence then costs us thousands of defective products, which, at best, can still be restored, some of them ended up in apartments with defects, while others flew into the trash heap, being simply written off for marriage.

In order for such unpleasant situations to happen less often, or even not to take place at all during the work process, it is important to know what can cause defects in paint and varnish coatings and what simple rules will help prevent their occurrence.

There are several of the most common factors that can ruin a perfect finish:

  • violation of the dyeing technology by the master;
  • inappropriate surface preparation;
  • poor quality of the painting material.

At the same time, if you know all the nuances, you can easily determine by the type of defects what mistake was made.

Therefore, further on the most common defects and the reasons for their appearance

Craters

In other words, it is any type or shape of notches and irregularities in the surface. They not only make the coating less attractive, but also reduce the anti-corrosion properties of the paint. The defect has the form of small pits up to 2 mm in diameter, located unevenly over the entire surface. Depending on the depth of the defect, the coating may lose its durability. Why do they appear?

  • incompatible material with solvent

If you do not adhere to the proportions indicated in the instructions, you can easily ruin the coating. Therefore, do not neglect the indicated ratios and advice on the selection of solvents.

  • wrong coating thickness

The paint layer must be thin and meet all standards, if you apply more paint than necessary – you should not be surprised that the entire coating will be in craters. Increasing the coating thickness changes the properties and drying speed, so the paint layer can deform and cause inequalities.

  • moisture

During staining, you must be sure of the humidity of the air. After all, the settling of condensate or any oil compounds causes craters.

  • bubbles in paint

Sometimes, during the mixing of paint, air enters its composition, and then small bubbles can settle on the painted surface, burst when dry and form craters. Therefore, it is important to always mix materials very carefully and observe how the paint is applied. After all, you can get rid of this defect while the paint is still liquid.

air pressure in application devices

In the case of the application of anti-corrosive materials, it is important to monitor the paint and air supply pressure inside the devices to avoid uneven paint supply.

Not in all cases it is possible to get rid of craters. The most common option is to sand the coating layer and reapply. However, it is still much better to follow the rules and paint successfully and efficiently on the first try.

Shagreen paper, paint clots or streaks

For some, shagreen may seem like an interesting coating option, because the orange peel effect can also look quite interesting, but not when it suddenly appears in small spots on a smooth surface. Usually this defect is characterized by a collection of small tubercles. Such a defect can be caused by:

  • violation of viscosity (high viscosity of the paint, due to which it is applied unevenly and does not smooth out on the surface when drying, but collects in separate clots. Insufficient viscosity of the coloring material leads to the fact that the paint runs off with stains)
  • the distance between the gun and the thing to be painted is not enough (this also causes layers of paint, due to which it lies unevenly)
    inappropriate proportions (they can be expressed not only in the form of craters, but also, for example, lumps. If you add a lot of solvent or do not stir to the end)
  • increased room temperature (leads to the fact that in some places the solvent evaporates much faster and causes the formation of an “orange peel”)
  • layering (sometimes products require re-coating, but if you do not wait until the first layer is completely dry, the next one can form stains)

It is very important not to neglect the above reasons for the formation of defects, because the line is very thin. For example, moving the spray gun too close to an object can produce shagreen or a layering effect, but holding the tool too far can cause streaks.

Rubbish

One of the most unpleasant reasons, because any dust, for example grinding dust, or a small lint, when it hits the surface, visually immediately creates a defect. These can be both the results of an insufficiently cleaned surface, and a dirty room in which dyeing or contaminated clothing of the master takes place.

Crackle

One of the defects that cannot be corrected in any way. Indeed, in fact, this is not a visual defect, but the loss of a protective layer: it simply peels off and falls off. Why is this happening? This could be:

  • too thick layer;
  • applying a quick-drying coating to an unfinished preliminary;
  • incompatible materials;
  • increased viscosity.

So, the main mistake is non-compliance with the rules according to which painting should be performed. All this can easily turn any product into trash. After all, painting is not only the creation of a protective layer, but also the final appearance, which is also important for the user. All requirements are not so complicated: cleanliness, correct temperature, proportions and application technique. By following them, you can achieve better results.

Дефекты порошковой окраски

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