liquids 1 and 2 fully wet the surface as shown by their low contact angles, so they should be neglected when first drawing the line of best fit to find the critical liquid surface tension needed to effectively wet the pc surface, γ, which is simply the x-intercept of the best fit line for the zisman plot. to find the best fit line a least squares regression is recommended by using a computer program such as microsoft excel, minitab, matlab, or it can also be done using a modern graphing calculator such as a ti-84. this was done with the data from table 1 and the fit data for liquids 3,4, and 5 can be seen on figure 3.