I have used a solution of MEK [methyl ethyl keytone] with clean white styrofoam. I add the styrofoam to the MEK until no more is dissolved. I then drill my blanks and pre-turn them down a bit. I then cover the blanks in the MEK solution and pull a vacuum of 5-10 pounds of vacuum for several minutes to an hour ... any more and the MEK is "boiled" off way to fast to allow a complete soaking throughout the blank's walls. I remove the blanks, re-mill the ends and inside of the tubes, and then turn to shape. The MEK is available from major paint stores, the styrofoam from common packing materials. Colored styrofoam I have not tried. The MEK is VERY volitile and the vapor is dangerous to your health. The vapor will also attack any plastic nearby as well as many finishes on furniture - proper ventilation is a MUST. Be aware that MEK boils rapidly under even a mild vacuum, so an overflow is possible. Plact your holding jar in a larger casn to catch the overflow. Practice will dictate what you need to watch out for. Just DO NOT BREATH the MEK fumes.
Fred