This is my first post and hopefully many will follow on this great site!!

Swim's planning his first STB extraction, and as advised he's reading allot of topics to gather information, also to understand chemical reasons behind steps in different teks. Now Swim is confused about the washing part since he red different advices. Some say a sodium carbonate wash is completely useless when you plan to do a re-x, the FAQ says washing could be useful if one was sloppy, but otherwise not strictly necessary, other say that once you did a sodium carbonate wash, a re-x would be useless.
Swim would like to know:
1: What exactly will be cleaned with a sodium carbonate wash and what with a re-x?
2: If you want to be thoroughly, do you need to do both a sodium carbonate wash and a re-x?
3: If you don't want to do both, which one would more effective?
I'm Dutch and still working on my English, so sorry if i made some mistakes in writing:-)
Thanks!!!
Peace:-)