The aim of this study was to explore the possibility of modifying the surface of the polymers by commercial agents that are available in everyday use. The following materials were used: low density polyethylene (PE-LD), high density polyethylene (PE-HD), polylactide (PLA), cycloolefinic copolymer (COC), and materials that are used in additive manufacturing and are in the form of filaments: poly(ethylene terephthalate)-glycol (PET-G) produced by Devil Design, F41 FLEXTM and F43 TOUGHTM, produced by Forefront and Z-GLASS produced by Zortrax. CLEAR resin, produced by Formlabs, was also used to examine the possibility of modifying its surface. This resin is used as additive manufacturing material by stereolithografy. Commercial agents used for surface treatment are sprays Bama Power Protector and AntiAqua, Nano Vario foam, Rain-X and Bison Enamel Fix and 9HMR-FiX coating. The primary purpose of surface modification was to increase its hydrophobicity. Hydrophobic are those surfaces whose contact angle with water is greater than 90°, while surfaces with a contact angle less than 90° are called hydrophilic. The contact angle is defined as the angle that closes the tangent withdrawn to the edge of the liquid drop and the surface on which the drop is located. During the experiment, the contact angle of cleaned, as well as the treated surfaces of the material with water, formamide and diiodomethane was measured, and from the obtained results the free surface energy was calculated. The FTIR (Fourier transformation infrared spectroscopy) spectra of each individual agent used for surface modification, as well as the surface area of the material with and without the applied agent were recorded. As satisfactory modification agents, Bama Power Protector spray and Nano Vario commercial impregnation foam have been shown, and the effect of surface treatment of these agents on the formation of droplets at the output of the reactors produced on the 3D Form2 printer was investigated. Surface treatment in some reactors influenced the appearance and homogeneity of droplets.