Based on the suggestion from class last week, i went to home depot a couple more times and finally found a usable material: ABS pipes.
However, there are a few modifications need to be done. First, the pipe is not see-through anymore, so i drilled holes on the side to be the observation window. Second, the idea of a convection cylinder requires a enclosed curve surface, meaning i need to cover up the holes with transparent material. So i bought clear acrylic sheets and plastic glue to cover up the holes. I tried laser-cutting the acrylic and gluing them on, but they just wont bend enough. After a few shatters i realized that acrylic is probably not the right material. so i had to go with clear packaging tape as backup.
after the piece is all sanded and ready, i assembled the cylinder wall onto a linear slider. There were also rack and pinion set that i tested with, but there was simply not enough torque to drive the entire piece. There were so much friction even with the slider design that it was impossible to move it with anything else but hand. One advantages is that at least it guarantees a steady liner motion, which helps to observe fire behavior as the convection chamber opens up.
In terms of fire coloring ingredients, I bought methanal, a blue-white flame as the base of everything. I did some testing with the wick of tea-light candles, but the carbon inside would always produce a yellow flame. Tablesalt is another coloring ingredient for yellow-orange flames. What i didn’t expect is the Borax detergent, it does produce green fire out of its boron ions, but there are also a combination of other ingredients that make the flame orange. So what end up happening was the flame would change color as different parts of the salt burns, and producing a mix of color that’s changing.