The clinical effectiveness of tissue conditioners is influenced by their gelation characteristics and viscoelastic properties after gelation. The purpose of this study was to evaluate the effect of addition of ethyl alcohol (EtOH) on these properties, and to compare the effect of EtOH with that of the powder/liquid (P/L) ratio. Three tissue conditioners were used in this study. The gelation times were obtained with an oscillating rheometer. The viscoelastic properties after gelation were also evaluated by stress relaxation tests. Addition of greater amounts of EtOH produced the shorter gelation time and the larger flow after gelation. Conversely, although the use of a higher P/L ratio produced a shorter gelation time, this procedure leads to a smaller flow after gelation. The results suggested that the addition of EtOH to the liquids of tissue conditioners is an effective method for controlling gelation times and viscoelastic properties after gelation.