I've been testing "Jet-Lube Moly Mist" lately.
It dries to the touch quickly, but that can be deceiving because it's soft when it first dries and will rub off easily. It seems to last longer if you let it dry 15 - 30 minutes.
Even fully dry, it still has a tendency to rub off onto the mold, particularly at the sprue hinge. However, as long as there is lube between the sprue plate and the mold, that's all that matters.
Here's how it holds up after an hour long casting session. The moly has rubbed off the sprue plate around the hinge -- but now there's moly on the mold in that area, so it still gets the job done.
What impresses me is that there was absolutely no lead stuck to the bottom of the sprue plate at the end of the casting session. It seems superior to other lubes in that respect. All in all this is an acceptable sprue lube. I bought it from Zoro on ebay, or you can get it directly from Zoro's website.
Note that there are specs of lead stuck to the top of the mold. This is a common problem and perhaps could be prevented if I had also sprayed lube on the top of the mold (with bullets in the cavities so lube doesn't get into the cavities).
