Thanx a lot catlin for the words above. The smoke was postwork. I applied the "smoke" EyeCandy filter on a separate layer, then used it as a canvas to paint the smoke on on another layer. (EC filter tends to be slightly "flat", but it's very useful because you can set the wind, the turbulence etc). When I was enough satisfied with the mouse-painted third layer, I deleted the filter-layer, adjusted opacity to make my smoke more transparent and merged down. IMO, Bryce voluemtric smoke (applied to a sphere, or a cylinder, or whatever you like) could be way more effective than this... but I (ehm) simply forgot to put it in the image before rendering. :-| I tried to plop-render it after, but (dunno why) the final image showed clearly the outlines of the newly rendered box, so finally I switched to post (BTW, I have nothing against postwork, I use it a lot usually, but this time I simply wanted to do without). Stefano