Several years ago Nancy Dale Kinney provided her technique directions for marbelizing with smoke on one of the Yahoo lists I was a member of. I love this effect.
SUPPLIES: 1" candle, candle holder, Tablespoon
The surface to be smoked must have already been prepped with the background color and dried. To smoke light a candle in a holder and allow to burn a few minutes until you have a good tall flame. Hold the scooped side of the tablespoon over the flame until you get a black carbon build up on the spoon. Practice moving the spoon around over the flame until you see a steady stream of black carbon or smoke rising above the spoon. I have found that the spoon must be almost perpendicular to the candle. If the candle has burned a few min. you will have a better flame. You must use the standard 1" diameter candle. This stream of smoke is what adheres to the project piece. Hold your piece over the stream of carbon, moving the piece around so that the carbon will adhere to various places. Be careful not to let the spoon touch the surface. When you get the desired result, immediately spray with the Krylon Matte 1311 or the Liberty Spray. You can always go back and smoke again if you want more smoke even if you have sprayed. What ever spray sealer that you end up using just be sure that you can paint with acrylic on top if that is the medium you are using. On larger pieces smoke sections, spray, allow to dry and then smoke other sections. Spray to avoid smudging. To give the marbelized porject a more interesting effect, I wash in touches of color where there is no smoke. Wipe excess paint from brush and blend into the smoked areas a little. Allow to dry.