Some random guys review of the Lock Pro Clam Kit

[CapnCurry]

Excellent write-up, Snik! Very helpful, and very clear. I've already got my 158 bismuth on its way. But, I was hoping you might be able to offer some suggestions as to clay. I see you've written that Sculpey is the way to go, but I notice that Sculpey has different types of clay hardness - in your experience, is it generally better to go with a harder clay or a softer clay?

[Raccoon]

I forgot to note earlier; it seems the 158ºF Bismuth has much higher expansion than 117ºF Bismuth does when it cools.

158ºF Bi has an expansion property of .0051" per surface inch, while 117ºF Bi has a contraction of -.0002" per inch. So while 158ºF may be less expensive, it also creates a less accurate cast of the key. This can be crucial when molding a key for a lock that has tight tolerences. Especially laser cut keys. 117ºF Bi also has a higher hardness than 158ºF Bi, which is unusual for its low melting point, but pretty dang useful.

Compared to resins, though, any bismuth has much better cooling properties. Every epoxy I've used has high shrinkage. Thick amounts of epoxy also collapse leaving a huge dimple and possibly warped key.