Imbibition in pieces of paper with different shapes

We study theoretically and experimentally the wicking process in pieces of blotting paper of different shapes: rectangular and triangular strips and square strips where radial imbibition occurs. We find that in rectangular strips the dynamics of the capillary penetration yields the classical Washburn law while in the other cases logarithmic corrections respect to this law are obtained. Our experiments are in good agreement with the theoretical predictions.