  Consolidation of colloidal gels results in enormous stresses that are usually
released in the formation of undesirable cracks. The capacity of a gel network
to crack during drying depends on the existence and significance of a pressure
gradient in the pore liquid; in addition it depends on the way the gel relaxes
the resulting drying stresses. In this paper the effect of a binary mixture of
solvents saturating the gel network on the crack patterns formation is
investigated. Indeed, incorporation of a small quantity of non-volatile
cosolvent, i.e. glycerol, inhibits drying-induced cracks; moreover addition of
a concentration greater than 10% to a colloidal dispersion leads to a crack
free coating in room conditions. Mass variation with time reveals that both
evaporation rate and cracking time are not affected by glycerol, in the range
of added glycerol contents studied. In addition measurements of mechanical
properties show that the elastic modulus is reduced with glycerol content. The
decrease of the number of cracks with the glycerol content is related to the
flattening of the pressure gradient in the pore liquid. The mechanism is shown
to be due to the combination of two processes: flow driven by the pressure
gradient and diffusion mechanisms in accordance with Scherer work (1989).
