Fossil reintegration is an unreliable field regarding intervention criteria and materials used according to the characteristics and requirements of specimens. Generalized use of epoxy fillers in different kinds of gaps suggest that an in-depth study on more reversible gap fillers for small to medium fossils is necessary. This paper investigates the physical-mechanical comportment of six gap fillers of three different families of resins: vinyl, acrylic and epoxy. Samples have been tested according to their working properties, aging properties, and affinity with paleontological materials. A physical-mechanical characterization has been done to gap fillers according to different parameters. Moreover, accelerated artificial aging tests have been done in all samples. After that, changes have been quantified with several analysis techniques.