What's wrong with my alumilite????

[Monty]

Last Saturday I mixed equal amounts by weight and added several drops of white for contrast color with coffee beans. It finally got hard enough to remove from the mold Sunday afternoon, but the outside of the blank is still sticky today. The blank I cast is approx 6X6X1.

 

[MesquiteMan]

Mannie,

Did you make sure your beans were 100% dry? That is the only thing that causes Alumilite to be sticky that I have found. I have not done coffee beans, however. EVERYTHING that I cast in Alumilite is put in a toaster oven at 190 or so fo a few hours before casting to make sure it is dry. Since I started doing that, I have not had any issues like you mention. The only other thing it possibly could be is your colorant. If it is not Alumilite brand then you are sorta on your own with trial and error. Of course if you put too much you will certainly have a problem. It does not sound like you did, though, so I was strongly suspect the later.

Go ahead and put the block in a toaster oven for 2 or 3 hours and the sticky should go away.

 

[jthompson1995]

I've run into some similar issues with the clear alumilite. I think the issue comes from the temperature. My shop is in my basement and usualy pretty cool. Any time I have cast with the clear, it has been soft, though not sticky, and hard to remove from the mold. The directions say to heat the molds, especially on thin castings. I have not done this and usually need to leave the molds in the pressure pot overnight to be sure they will harden enough not to let bubbles reappear. After day or two, though, the blanks harden up fully and are not sticky at all. You probably could heat them to hasten curing, or actually follow the directions and heat the mold before casting.[}]

I have used the alumilite white for casting coffee beans and have not had any of those issues. I do not need to add any colorant, it's thinner than the clear (better penetration into the beans), and unmolds easily within 15 minutes.