This is a video of raku and smoke fired work .To get the intence black that you see the smoking was done in a sagger with just a handful of dry wood shavings in the bottom of the sagger not touching the piece to be smoked, if need be dry them first, as moisture can leave marks on the work.Then i fire slowly to 750c. The black is better if the piece has a layer of a high fire clay or porcelain terra sigilata on it.

This piece was slab built with a turned lid. When bone dry it was painted with a terra sigillata. Then bisc fired. Then a soda solution was added to the higher parts of the surface and a low temp glaze to the inside of the bottle then refried to 1030c. Then it was smoke fired in a  sagger with about 3 hand fulls of sawdust to 750c. The smoke takes on parts not protected by the soda solution. Note that when adding the soda solution it does bleed a bit so not too much on the brush. this soda solution can also be colored with a stain or pigment to give a stronger effect if you want.