Originally Posted by ckcowl

your needle size needs to be correct for the chosen thread- really has nothing to do with the fabrics- other than using the correct type of needle for the fabric being sewn-
visit the Superior Threads web site- they have free charts you can print off that tell you all the different needle types/sizes their recommended uses- and the threads- weights/types, what needle to use with what thread for what.
it is a great resource- will answer many of your questions.