## 1 Introduction  
Over the last two decades or so, additive manufacturing products have become an irreplaceable part not only of technical practice but also of, e.g., medicine or the food industry [1; 2]. The advantage of 3D printing technology lies mainly in the possibility of creating shape-variable components. This fact also results in a high degree of freedom in the design of the product [3]. An indisputable advantage here is also the speed of component production [4]. A high degree of independence from the functionality of logistics flows is also important. This point of view plays a very important role nowadays due to component production failures on the part of suppliers or non-compliance with delivery deadlines in the just-in-time logistics system [5]. On the contrary, among the disadvantages of 3D printing can be included, in particular, the formation of cavities, which is associated with the deterioration of the mechanical properties of the products. However, the mechanical properties of 3D prints can be improved by using composite materials [6]. The use of surface treatments also leads to improvements in mechanical properties. This effect was noted in the case of the chemical smoothing of the 3D print surface, e.g., with acetone [7; 8]. It is also possible to apply coating layers. The application of coatings based on, for example, organic paints, mineral oils, metal layers, resins, or silicones can be included in this category. All of the above-mentioned coatings can be applied to polymer substrates [9]. Another post-processing technology includes annealing. The method consists of three steps: heating above the temperature of the glass transition, endurance at this temperature, and gradual cooling. This process releases residual thermal stress, increasing the strength between the individual layers of the 3D-printed parts. The resulting product is, therefore, more resistant to external influences [10]. A positive effect on the mechanical properties of the material was also noted, for example, when combining a filament with a content of thermally expandable microspheres and subsequently annealing it [11]. To create the most durable part possible, the choice of 3D printing parameters is also very important. These parameters are mainly the density of the filling, the orientation of the part during the printing process, the thickness of the layer, the style of application, and the speed of extrusion of the material, as well as the diameter and temperature of the filament during printing [12; 13; 14]. The most frequently used degradation tests not only include UV radiation [15], but also cyclic tests involving a combination of freezing, thawing, and changes in relative humidity [16]. The test mentioned can be extended, for example, by placing the material in a salt solution [12]. In this case, the test simulates the exposure of the samples to seawater [17]. This type of degradation test is used to evaluate 3D prints not only in the engineering industry but also, for example, in the construction industry [18]. However, due to the mentioned conditions, this test can reliably simulate the working cycle of the components in winter (snow slush with road salt, frost at night, icing during the day). The essence of the test is the penetration of the salt solution into the cavities (pores) in the surface of the material (at temperatures above the freezing point) and the subsequent initialization of the formation of microcracks. This phenomenon occurs when the samples are frozen as a result of the increase in volume of ice, which loads the walls of the cavity until cracks appear. When temperatures rise above freezing, these cracks lead to an increase in brine absorption, which initiates the formation of a network of additional microcracks that later function as individual cavities. If the temperatures drop below freezing again, the formed ice again weighs down the walls of the new cavity, and the degradation cycle continues like this again.