I agree with Penman1 also. I use both Silmar 41 polyresin and Alumilite. Both work well with turning but have their own pros and cons. For clear casting objects on the tube like snakeskins, feathers, labels and things you want to use polyresin. Alumilite doesn't adhere well in that application. If your casting worthless wood or pinecones, acorns, and similar, I would suggest Alumilite, which adheres very well to this type of casting, plus Alumilite does not shrink when curing like Polyresin does. Both work well with color casting but I think you can keep better color separation with Alumilite because it cures so fast.
With Alumilite you have about seven to eight minutes to mix, stir, pour and pressurize in the tank so you need to have a plan and stick to it, not to mention having a stop watch helps. Cure time is about 1.5 to 2 hours so its out of the tank much quicker. Another draw back is you cant make multiple pours with it. It wont stick to itself very well the second time. The polish and shine issue can be fixed with a CA finish. Its more durable, especially when you drop a pen on a hard surface.
With polyresin you have twenty to thirty minutes, sometime less in warmer climate, to work and chamber it. Polyresin smells and shrinks as it cures, and you will want to wait 12 to 20 hours for proper curing before removing from the pressure tank. Its also good for multiple pours so you can recast a blank later if you need to, and it polishes up very well. Ive dropped a few pens and cracked them on a hard tile floor.
Im sure Ive over looked some info but this was what I experience with them. There are many who know more than me. When it comes down to what type of Alumilite you want, I would ask someone like Curtis "MesquiteMan" or those who have a lot of experience with it. Good luck!
