I've always cut a chunk off the block, and put it in an Altoids tin.
With the top off, I set it on my woodstove (or oven burner), and get the fire going.
I let it liquify completely, and then remove from heat (Carefully, that tin gets hot.).
As it cools, it will begin to thicken up. Carefully test with your finger. When it's right, the cosistency is like Crisco.
(Note- if put on a cool surface like a room temp plug, it will thicken too fast. Warm your parts up first.)
Legion