Casting: Which Resin to Use?

I recently started turning hybrid blanks because I liked the freedom of choosing different combinations of wood and colored resin. After some research and testing, I settled on Alumilite Clear, a urethane based resin.

Benefits to using a urethane resin over other types include low odor, quick set times, and a finished product that can be brought to a mirror polish. Alumilite Clear resin will be ready to machine in 24 hours, while other resins can take up to 72 hours.

Finished hybrid blank and Alumilite

To eliminate air bubbles from the casting, I needed to use a pressure pot during the curing process. Unlike epoxy resins, using a propane torch will not work due to the speed at which Alumilite cures. I used between 35 to 40 psi of pressure on the poured casting for no more than 90 minutes. I quickly learned to be very exact while weighing the two parts of the resin as variances caused longer or incomplete drying times.

I started with Australian burls for the wood base and used both TransTint and Alumidust in the resin. I quickly found a little bit goes a long way—the first casts were almost too opaque to see the burl.

The author turning a hybrid blank

Alumilite is not meant for stabilizing wood. Other resins such as System Three MirrorCast are much better suited for stabilization or filling cracks and voids. I tried using MirrorCast for one of my hybrid blanks, but found the cure time was too long and the finished product had a slightly colored tone.

Looking back, I’m glad I decided to try my hand at casting and turning hybrid blanks. Not only was it a great learning experience, I feel there is a long road of experimentation ahead.