A linear dispersion relation is derived for the collisional gradient drift instability under the assumption that partial short-circuiting of perpendicular ambipolar electric fields, ion inertia, and ion viscosity are the significant factors in the ''freezing'' of striations with perpendicular scale sizes of several hundred meters. Quantitative evaluation of this dispersion relation indicates that eigenmodes tend to be localized to low-density portions of the plasma when short-circuiting is active. However, the eigenmodes can extend in relatively uniform fashion across the density gradient when short-circuiting is very small. This situation would appear to be conductive to the formation of striations. Hence the calculations suggest that short-circuiting of perpendicular ambipolar electric fields is weak at the sharp perpendicular density gradients where striations begin to evolve. The observation of perpendicular density gradients which are persistent and sharp supports the idea that short-circuiting is weak. With the assumption that short-circuiting is zero, a dispersion relation is derived with full ion viscous contributions. Evaluation of this dispersion relation suggests that the finite ion gyroradius contributions are the dominant factor in striation ''freezing.'' Accordingly, an expression is derived for estimating the outer scale wave number appropriate to ''frozen'' striations, and an appropriate application is made to the ''U-shaped curve'' formulation of striation dynamics.