<p>FDM method has become an ever-growing process for manufacturing cost- and time-effective parts. The staircase and ridge effect caused by this method result in poor surface quality and compromise surface integrity which leads to low functional performance. Various post-processing techniques have been developed to achieve desirable surface quality. Among them, chemical polishing techniques are most effective. A lack of thorough investigation and microstructural analyses into chemical post-processing on the most popular material, PLA, exists. This study aims to investigate the effects of different chemical polishing techniques, different chemical solutions, and different durations of treatment on surface integrity and mechanical properties of additively manufactured PLA parts using FDM method. A randomized full factorial design is used with the help of Minitab DOE software. Two different chemicals, acetone and dichloromethane; two chemical polishing techniques, immersion and hot vapor; and five treatment durations of 90, 180, 360, 540, and 720 s are deployed. Chemical post-processing techniques used in this study has shown remarkable improvement in surface integrity with a maximum of 97% and 95.85% reduction in surface roughness parameters of Ra and Rz, respectively. However, it is observed that chemical polishing slightly compromises tensile strength of the samples. A maximum reduction of 38.3% in ultimate tensile strength is calculated. Treatment mechanism analysis shows that chemical treatment tends to flatten peaks by liquefying them and filling valleys by pushing them into valleys. Microstructural analysis depicts that solvent penetrates parts and reshapes their inner structures, resulting in sponge-like and porous structures.</p> Graphical abstract <p></p>