How do you know when alumilite is too old? Does it simply no longer set up solid? I have some clear slow that's been sitting unopened for several years. I used it yesterday and much to my surprise it set up just fine. It's still curing so I haven't tried cutting it into blanks yet. I'm a little hesitant to do any more using it in case it's no good but don't know how to tell. I'm casting worthless wood that's been stabilized so I don't want to waste it. On the other hand, now that it's open I want to get at it.