First let me welcome you to FSM seeing as this is your first post here.
Here are 2 threads that cover your question pretty good.
http://www.finescale.com/fsm/community/forum/topic.asp?TOPIC_ID=2278
http://www.finescale.com/fsm/community/forum/topic.asp?TOPIC_ID=3647
Happy Modelling and God Bless
Robert