This paper concentrates on the densification of sol gel derived thin nano-ceramic coatings by laser radiation and by furnace treatment. Deposition of the film is done by means of spin coating of Zirconia. The sintering of the layer is observed using a number of different measuring techniques. Especially, attention is paid to the densification behavior and the grain growth in the layer, investigated by scanning electron microscopy and ellipsometry. Also the different crystal phases observed are addressed. During sintering at a constant temperature a change in the sintering behavior with time is observed. This change is observed for most temperatures. Both the initial fast sintering of the process (for all sintering temperatures), and the final slow sintering (only at the higher sintering temperatures) are explained.