Alginate, discovered in 1881 by British chemist E.C.C. Stanford, is a polysaccharide isolated from seaweed. Since its introduction into dentistry in 1940, it has been used as an impression material due to its hydrophilic and hydrophobic properties, which allow dimensional changes during impression and solidification. For optimal impression, type 3 plaster is recommended, which presents lower expansion and longer setting time, ensuring dimensional accuracy. In addition, the stability of the dental model is crucial, including mechanical and dimensional strength. Plastic and metal trays offer different advantages and disadvantages in impression taking. 126 plaster models made with 9 brands of alginates were reviewed: Super Gayz, Kromopan, Tulip, Cavex CA37, Alginoplast, Tropicalgin, Tulip Color Switch, Max Print Cyan and Biogel. The models were divided into three groups according to the type of tray: perforated plastic, perforated metal and smooth Rim Lock type. Each group was evaluated by gelation tests with room temperature water and cold water (4°C), using plaster types 2 and 3, and either removing the plaster immediately or after waiting 4 minutes. The distance between the central development groove of the lower left first molar and the central development groove of the lower right first molar was measured as 44.16 mm. When analyzing the perforated plastic trays with plaster types 2 and 3, the brands Super Gayz, Kromopan, Tulip, and others maintained an average of 44.15 mm with plaster type 2 and 44.15 mm with plaster type 3, showing consistent results in dimensional accuracy.